Glossary
Video Standards
Glossary
Victor Steinberg and Julian Warren
© 1996-97 Snell & Wilcox Ltd. All rights reserved
Glossary
Glossary
Glossary
0h
10-Bit
See: Line Datum
The generic description for equipment having
a data path ten bits wide. Such a path can
represent data having up to 1024 different
values (four times that of an 8-bit system)
0v
See: Frame Datum
100% [Colour] Bars
1. In PAL/SECAM countries and in Japan:
Colour
Bars
with
the
nomenclature
100/0/100/0
2. In the USA and other NTSC countries:
Colour
Bars
with
the
nomenclature
100/7.5/100/7.5
1024x768, 1280x1024
The numbers represent the size of two of the
most popular computer display formats. The
measurement is in horizontal and vertical pixels
respectively.
2.5D Effect
A digital video effect similar to a 2D Effect but
with the appearance of 3-dimensions. E.g. a
picture can be distorted and put on the
surface of a disk to give the illusion of being
put on a sphere. If this disk is rotated 90
degrees about its x-axis it will nevertheless be
seen to be a single line, proving its 2D nature.
A true 3D Effect may be rotated and viewed
about any axis and still maintain an
appropriate shape
2D Effect
A digital video effect where picture
transformations
and
manipulations
are
restrained within an arbitrary plane surface.
2H
Sync pulse with period of two lines, the rising
edge of which marks the start of a line with
positive polarity of V component in PAL
chrominance signal or the start of a Dr line in
Dr/Db sequence in SECAM chrominance
signal
Synonyms: 7.8 kHz; Dr/Db Switch; PAL
Switch; PAL Switching Signal; SECAM
Switch
Glossary
2T Pulse
4:2:2:4
A Sine-Squared Pulse with the half-amplitude
duration equal to two times T Unit, so the main
lobe of its frequency spectrum nearly matches
the bandwidth of the TV system. At the output
of an ideal system the distortion of the 2T-pulse
(usually expressed in ’’K-rating’’) should
approach zero.
Relatives of this signal are the 1T-pulse (double
bandwidth) and Composite Pulse etc. The
purpose of the 1T-pulse is to examine the
effect on equipment of a signal with greater
bandwidth than that specifid by the TV
System. The 1T pulse also helps to examine
symmetry of ringing (linked with Group Delay
Group Delay distortion)
An interface and processing format usual for
video graphic workstations and digital video
effects devices. It has a separate physical
interface to carry the key signal with 13.5 MHz
sampling rate (the last ’’4’’ in the format
formula)
3D Effect
A digital video effect where picture
transformations and manipulations are not
constrained within a planar surface. E.g. a
picture can be distorted and put on the
surface of an imaginary sphere. If this sphere is
rotated 90 degrees about its x-axis, it will still
appear as a sphere but with a different
fragment of the input picture visible. Any
desired distortion may be described by the
term ’’3D effect ’’ e.g. , the nose of the actor
can be elongated preserving its general
shape
3x4 [format]
See: 4:4:4
4:0:0
A monochrome digital video format used only
for key signal interchange in video mixers,
chroma-keyers and DVEs
4:4:4
An interface and processing format used by
some digital video devices. It requires three
physical interfaces to carry separate R, G and
B digital signals
Synonyms: 3x4 [format]
4:4:4:4
A digital video format that has identical
sampling rates for the luminance, colour
difference and key signals. A 4:4:4:4 signal,
sometimes called 4x4, is usually transmitted as
two separate 4:2:2 signals. These signals are
generally referred to as 4:2:2 and 2:2:4. The first
signal contains the wide band luminance
signal and half of the wideband colour
difference signal. The 2:2:4 signal contains the
other half of the wide band colour difference
signals plus the key signal
Synonyms: 4x4 [format]
4fsc
Four times subcarrier sampling rate used in
digital composite systems. Also used as a
jargon term for the actual Digital Composite
signals, avoiding the need to refer to D2 and
D3. 4fsc is also written as 4Fsc and 4*Fsc and so
on!
4x4 [format]
4:2:2
See: 4:4:4:4
1. Interface and processing format widely
used for digital video devices. Often
incorrectly identified with CCIR Rec 601 that
cover the whole family of formats
2. Generic label widely used on any device
that operates somewhere internally in 4:2:2,
but may, or may not, actually have a Rec. 656
digital interface
601
4
See: Rec 601
7.8 kHz
See: 2H
Glossary
75% Colour Bars
Active Lines
1. In PAL/SECAM countries and in Japan:
Colour Bars with the nomenclature 75/0/75/0
2. In the USA and other NTSC countries: Colour
Bars with the nomenclature 75/7.5/75/7.5
The lines of the TV frame carrying picture
information, i.e. all frame lines except the
vertical blanking interval. Normally the number
of analog active lines is smaller that the
number of digital active lines
8-Bit
The generic description for equipment having
a data path eight bits wide. Such a path can
represent data having up to 256 different
values
95 % [Colour] Bars
Colour
Bars
100/0/100/25
with
the
nomenclature
Synonyms: Analog Active Lines
Active Part
The part of TV line carrying picture information,
i.e. equal to the line period minus Horizontal
Blanking Interval. Analog Active Part is
normally shorter than Digital Active Part.
Synonyms: Analog Active Part
A-B Mix
Active Picture Area
See: Cross-Fade
See: Active Image Area
A/D
Adaptation
See: Analog-To-Digital Converter
A method of subjective improvement of video
processing device performance by dynamic
change of hardware settings dependent on
the current TV picture content. Adaptation
exists in many forms, e.g. long time-constant ,
frame-by-frame, field-by-field, line-by-line and
pixel-by-pixel
AC-3
Dolby’s trademark for digital sound system
with either 2 or 5.1 channels. AC-3 multichannel sound provides five completely
separate (discrete) channels: Left, Centre,
Right, Left-Rear and Right-Rear, plus a
common Subwoofer channel. The nominal
digital bit rate is 384 kilobits per second
Synonyms: Adaption
Adaption
ACC
See: Adaptation
See: Automatic Chroma Gain Control
Adaptive Comb Decoder
Action Track
A digital video effect where fast moving
objects appear to remain on screen as a sort
of permanent Multi-Grab. This effect requires
motion detection to isolate the moving
objects so that they alone can be frozen and
accumulated in an overlay image. The
technique was developed specially for sports
action replay analysis
Decoder with Adaptive Comb Filter
Adaptive Comb Filter
A comb filter with Adaptation, i.e. with its
response modified by measurement of picture
content
ADC
See: Analog-To-Digital Converter
Synonyms: Image Trail-Freeze
Active Image
Active Parts of all Active Lines of the Frame
Active Image Area
Area of the display screen, occupied by TV
programme related picture
Synonyms: Active Picture Area
5
Glossary
AES/EBU [Digital Audio Interface]
Analog
A commonly used digital audio interface
specified as a result of co-operation between
the Audio Engineering Society and the
European Broadcasting Union. It is a serial
transmission format for two-channel linearlyrepresented digital audio data. Each audio
sample is carried by a sub-frame containing:
20 bits of sample data, 4 bits of auxiliary data
(which may be used to extend the sample to
24 bits), 4 other bits of data and a 4-bit
preamble. Two sub-frames make up a frame
which contains one sample from eah of two
audio channels. Frames are further grouped
into 192 frame blocks. AES/EBU signal includes
channel status data containing information
about signal emphasis, sampling frequency,
channel mode (stereo, mono, etc.), use of
auxiliary bits (extend to 24 bits or other uses),
and a CRC (cyclic redundancy code) for error
checking. There are several allowed sampling
frequencies within the 32 kHz to 48 kHz range,
the most common of which are 44.1 kHz and
48 kHz.
Used to describe the traditional system where
the signal level, for instance, voltage, at some
point is analogous to the signal being
represented. Variations in voltage represent
variations in signal value. Significantly, the
analogue signal may vary continuously from
maximum to minimum, with an infinite number
of different levels. This differs from digital
systems, which only have a finite number of
different levels. Analog systems have to use
electrical levels to represent signals, they
could even use oil flow or pressure as in aircraft
control systems
Alias
A form of distortion associated with signal
sampling. If samples are taken often enough,
the digital signal will be a faithful reproduction
of the analog signal. To achieve this, the
sampling frequency must be at least twice the
highest frequency found in the analog signal
being sampled. This minimum sampling
frequency is often called the Nyquist
frequency. For example, if the highest
frequency
in
the
original
signal
is
2 MHz (2 million cycles per second), then the
Nyquist frequency is 4 MHz (4 million samples
per second). If the original signal is sampled at
a not high enough rate, e.g. at 3.5 MHz, then
the digital version will contain not only wanted
2 MHz signal, but erroneous signal at 1.5 MHz,
i.e. artifacts that are not found in the original
ignal. These erroneous components of the
digital signal are called aliases. The resulting
signal is then said to contain aliasing. Because
of this aliasing it is not more a correct
reproduction of the original.
Synonyms: Aliasing
Aliasing
See: Alias
6
Analog Active Lines
See: Active Lines
Analog Active Part
See: Active Part
Analog Component Format
Format, where the colour difference signals Pr
and Pb have exactly the same peak to peak
amplitude as the luminance signal Y, i.e. 700
mV into 75 Ohm load for 100 % saturation
Synonyms: Parallel Analog Interface
Format
Analog-To-Digital Converter
1. In a narrow sense: A device (usually, a
micro-chip) which transforms a signal from
analog form to digital form. This is done by
taking samples of the analog signal at regular
intervals. Each analog sample value is then
quantized into a binary code.
2. In a wider sense: Device performing all
functions, necessary to convert analog video
signals to a specified digital interface format,
in particular sampling frequency genlocking,
video signal pre-filtering, black level clamping,
sync code word isertion, and even parallel-toserial conversion
Synonyms: A/D; ADC
Analysis
See: TV Analysis
Glossary
Anamorphic Format
AntiPAL [Test] [Pattern]
Viewed picture format with geometric
deformation of the widescreen picture aimed
to achieve full vertical screen occupation
while using the conventional TV display
A test pattern with deliberately wrong PAL
switch function: the polarity of V component is
not switched and polarity of U component is
switched.
This
pattern
enables
the
measurement of the performance of line
averaging function in PAL decoder: when it
works correctly, the pattern looks colourless
because
the
AntiPAL
test
pattern
chrominance is cancelled by the decoder’s
line averager
Ancillary Data
Non-video data transmitted within video data
stream, e.g. embedded audio data
Anti-Aliasing
A filtering process to prevent aliasing or to
reduce the aliasing that is already in the signal,
i.e. the prefiltering or postfiltering of any data
to ensure that they are suitable for the
particular sampling structure being used. For
instance, smoothing out diagonal lines or
curved surfaces in a digitally generated wipe
pattern, or text from a character generator
are particular cases of anti-aliasing. With
reference to images it commonly means
prevention of ’’jaggies’’ . Removal of the same
artifacts afer sampling is usually more difficult
and normally involves greater softening of the
image.
Aperture
1. In general: The smallest elementary SpatioTemporal area addressable by the process of
scanning.
2. With application to filtering: The
configuration and weights of taps defining the
filter function in spatio-temporal domain
Aperture Correction
Horizontal,
vertical
or
two-dimensional
processing of video signal with purpose of
correcting frequency response distortions or
enhance the sharpness of the TV picture.
Synonyms: Antialias
Synonyms: Enhancement
Anti-Bell [Filter]
APL
Filter in a SECAM coder to pre-emphasise the
chrominance
signal
after
frequency
modulation
1. Average level of luminance signal within
Active Image. Usually expressed as a
percentage of Reference White Level
2. As a name of test signal: ’’APL’’ is often
incorrectly used instead of ’’Flat Field’’
Antialias
See: Anti-Aliasing
Artifact [of a TV Picture]
See: TV Picture Artifact
Aspect Ratio
The ratio of the width of an object to its height,
usually expressed as two numbers separated
by a colon, e.g. 4:3, sometimes expressed
normalised, with a colon and number one
implied, e.g. 1.33.
Aspect Ratio Conversion
Conversion of the TV picture geometry
preserving the Scanning Standard, e.g. from
the so-called anamorphic format to letterbox
format.
Note that the video signal itself is aspect ratio
independent. A CCIR Rec. 601 signal may be
either 4:3 or 16:9. Only the display screen has
an aspect ratio, thus a ’’16:9’’ signal will appear
anamorphic on a 4:3 display.
7
Glossary
Audio/Video Combiner
Device serving to embed several digital audio
signals within a digital video signal stream
(usually using a serial digital interface)
Auto-Phasing
A vision mixer with auto-phasing has the ability
to compensate for timing differences
between its input signals so that it can perform
transitions free of shifts. This is usually
accomplished by built-in line or frame
synchronisers
Auto-Transition
A transition (e.g. a mix or wipe) which occurs
without the use of a manual control such as a
fader arm. Auto-transitions may be triggered
from a button on the switcher, or externally in
the case of an editor (e.g. via a GPI interface).
See: Take
Automatic Chroma Correction
See: Automatic Chroma Gain Control
Automatic Chroma Gain Control
Automatic
correction
of
chrominance
channel gain typically using subcarrier burst
level as a reference
Synonyms: ACC; Automatic Chroma
Correction
Aux
See: Auxiliary Bus
Auxiliary Bus
Some vision mixers have extra switching buses
that allow video signals connected to the
switcher to be fed to external equipment such
as digital effects systems, slo-mo VTRs, etc. The
Auxiliary Bus usually has no specific mixer
function, it is a utility feature
Synonyms: Aux
Average Picture Level
Average level of luminance signal within
Active Image. Usually expressed as a
percentage of Reference White Level
Back Porch
8
Part of the composite video signal within the
time interval from the trailing edge of the line
sync pulse to the end of the line blanking
interval. E.g. in 625 line systems the back porch
duration is 5.8 microseconds and in 525 line
systems
it
is
4.5 microseconds
Back Porch Clamping
See: Clamping
Back Porch Switching
See: Vertical Interval Switching
Background
1. Short form of the term Colour Background the same as Matte Generator
2. One of the video sources involved in keying.
Specifically, the background video is the
video that has parts of it replaced with the key
fill, or foreground video. When associated with
chroma-keying for example in a weather
report, the background is the weather map
and the foreground is the weather reporter
Background Generator
Usually part of vision mixer. The colour and
sometimes even the texture of the generated
background is adjusted with such controls as
’’Luminance’’, ’’Chrominance’’, ’’Hue’’, etc.
Synonyms: Matte Generator
Glossary
Bandwidth
BBC [Colour] Bars
1. The difference between the upper and
lower limits of a frequency range over which a
device or system will function, the limit being
normally specified as minus 3 dB voltage gain
(which is equivalent to half power)
2. Incorrectly used as the equivalent of
information-carrying capability of digital TV
systems, e.g. ’’the compression system has a 6
MHz bandwidth’’. The particular artifacts
generated by such systems may make
nonsense of the quoted frequency response
Colour
Bars
with
the
nomenclature
100/0/100/25 in 625/50/2:1 scanning standard
Bar
A common test pattern component. The Bar
looks on a TV screen as a vertical strip, usually
specified by colour, level and edge rise-time,
e.g. 75 % 2T White Bar. Sometimes the bar
component is called ’’window’’ or ’’box’’
Bar Tilt
Time domain parameter indirectly showing
low frequency response distortion by checking
Bar waveform. The tilt of the flat top of the bar
is usually expressed as a percentage of the
bar’s amplitude, ignoring overshoots
Synonyms: Tilt
Bars and Red
Popular two-part Test Matrix with standard
colour bars above red field. Useful for the
detection of VTR noise and moiré.
Note: professional jargon sometimes refers to
this signal as '
'
Bars in Blood'
'!
Synonyms: Split Field/Red
Baseband
General term describing the wide bandwidth
covering the range from several Hz to several
MHz; as opposed to the RF band which does
not include low frequency components
Synonyms: Video Band
BB
See: Black Burst
Bell Filter
Filter in a SECAM decoder to de-emphasise
the chrominance signal prior to frequency
demodulation
Betacam
Sony'
s trade name for component analog
tape recording format. The term is often
incorrectly associated with component
analog video interfacing in general.
Note: Originally the Betacam equipment
interface had Pr and Pb levels boosted to
1.333 times standard values. It is stiil so for 525
version of the equipment
Betacam Colour Bars
Historically these bars followed early Betacam
signal levels, giving rise to 75 % Colour Bars in
YPrPb format with PrPb gain boosted by a
factor of 1.333. At the right hand side of the
pattern the '
'
black set'
'test and 100 % white
bar are added. In the 625 version the white
level
is 700 mV, in the 525 version the white level is
100 IRE (714.285 mV)
Betacam SP
The Sony trademarked '
'
Superior Performance'
'
analog component video tape recording
format similar to the Betacam format.
Betacam SP players will playback Betacam
recordings but not vice-versa. Betacam SP is
recorded on oxide or metal tape
Betacam-SX
Sony'
s tradename for a component digital
tape
recording
format
with
signal
compression. Compression is similar to MPEG2,
but with fixed GOP structure to allow easier
edits. At the interface level it is compatible
with D1 format, i.e. conforms to Rec. 656.
Betacam-SX players can play back analog
component Betacam SP tapes
BF
See: Burst Flag
BG
See: Burst Flag
9
Glossary
Binary
Black Crush
The mathematical representation of any given
number in the base 2, i.e. with only two states,
0 or 1 (Also known as OFF or ON, LOW or HIGH
and FALSE or TRUE. This is essential for all digital
systems where there are only two possible
logical states, Low and High (typically
represented by levels of less then 0.8 V and
greater than 2.0 V respectively).
Jargon for unwanted compression of video
levels near Reference Black Level due to
signal path non-linearities or incorrect Black
Level settings. Sometimes done deliberately for
an improved ’’look’’
Bipolar Sync
See: Tri-Level Sync
Bit
A single binary information unit. Usually
represented by ’’0’’ or ’’1’’. As a jargon term can
be used to describe a single step of the
quantisation scale
Bit Parallel Format
See: Parallel Digital [Video] Interface
Format
Bit Rate Conversion
See: Sampling Rate Conversion
Bit Rate Reduction
See: Digital Compression
Black Level
1. Level of video signal corresponding to the
black areas of TV picture (zero brightness
areas)
2. Description of a common adjustment
control for altering the TV signal black level
(normally to restore nominal Black Level)
Black Level Clamping
See: Clamping
Black Limiter
A device preventing a video signal being
lower than some pre-set threshold near Black
Level
Synonyms: Black Clipper
Black Peak [Level]
Level of video signal corresponding to the
area of the TV picture with minimal brightness;
depends on the picture content, hardware
setting, etc.
Bit Serial Format
Synonyms: Peak Black [Level]
See: Serial Digital [Video] Interface
Black Set [Test] [Pattern]
Black and White
Same as PLUGE, but for Black Level only
Colloquial term used to refer to being ’’not
coloured’’, e.g. ’’black and white test pattern’’.
This term is acceptable only for informal
usage,
the
correct
expression
being
’’monochrome’’.
Blacker than Black
A Composite Signal with black level in Active
Parts of all Active Lines, It is usually distributed
as a reference signal for genlocking purposes
Jargon for the video signal parts below
reference black level, for instance, the
luminance signal overshoots after a white-toblack transition.
Note that CCIR 601 quantisation scale
provides 15 levels of headroom below
reference black to allow some Blacker than
Black throughput
Synonyms: BB
Blanking
Black Burst
Black Clipper
See: Black Limiter
10
The process of periodically setting the video
signal values to a predefined value during
predefined
time
intervals.
Traditionally
blanking is to Black Level during CRT fly-back,
but more generally may be taken as the
removal of spurious picture outside the Active
Picture Area
Glossary
Blanking Interval
Bounce
Time interval during which blanking is applied
A method of testing the very low frequency
response of video systems (e.g. clamping
performance) by periodic abrupt change of
picture content, in particular by the abrupt
change of Average Picture Level. Typically,
the bounce test is generated by interleaving
the test line with several stuffing lines and by
alternating the stuffing lines between black
and white. Usually the bounce rate is
adjustable through a wide range, e.g. from 0.1
Hz to 2 Hz
Blanking Level
The signal level transmitted during the blanking
interval. For Composite Signals it is the level of
luminance component at the Front Porch and
Back Porch. It commonly serves as a zero level
reference for all other video levels
Blinds [Wipe]
A periodic wipe pattern consisting of repetitive
identical stripes, a background image being
seen through these ’’venetian blinds’’. Changes
in the width of the stripes give the
appearance of the blinds opening and
closing. Of course the blinds themselves may
be either a Colour Matte or different live video
Block Matching
Method of Motion Estimation based on a
sequential search for a maximal correlation
between pixel blocks from the current TV field
and shifted blocks from the adjacent TV field.
Blur
1. Artifact in form of lack of Dynamic
Resolution
2. Generic term for out of focus (blurred), see
Defocus
BNC
Acronym for Bayonet Normalised Connector.
Alternatively deciphered as "Bayonet NeilConcelman", or even as ’’Baby N Connector’’.
The most popular type of connector in
professional TV and video
Border
A thickened edging, similar to a picture frame,
placed around a key signal, a digital effect, or
along the edges of a wipe. The thickness,
colour and softness of the edge are generally
adjustable
Synonyms: Edge
Bottles
See: Colour Identification Signal
Bowtie [Timing] [Test Signal]
Analog component test signal in a form of
frequency bursts put in Y and Pb, Pr channels.
The frequencies are intentionally made slightly
different so that the summation of two signals,
e.g. Y and Pb, produces a beating waveform
called ’’bowtie’’. The shape of the bowtie
clearly shows gain and delay inequalities
between channels
Box
1. Test pattern in a form of white box on black
or grey background. A change of window size
provides an easy way to control Average
Picture Level
2. A mode of test pattern or wipe generation
where the main signal is gated by a window
signal to provide a background image at the
perimeter
Broad Pulses
Pulses within vertical sync group. Each being
slightly narrower that half line period. Originally
conceived (along with equalising pulses) to
improve the performance of early field sync
separators. In a 625 line system the five broad
pulses are each 27.3 microseconds in duration
Broadcast [TV] Standard
See: Broadcast TV Standard
Broadcast Quality
A level of picture and/or signal quality which is
assumed to be acceptable for main
broadcast contribution, thus taken to mean
’’being of the highest quality’’.
Broadcast Television
Television with
public use
accompanying
sound
for
11
Glossary
Broadcast TV Standard
Bus
Set of technical specifications defining the
method of on-air radio-frequency transmission
of a TV picture with accompanying sound. The
Scanning Standard and Colour TV System are
also included in the definitions
Bump Mapping
1. In a wide sense: a bus is a signal pathway
which goes past many other points in such a
way that other signals may input to it or output
from it.
2. With application to mixers: a means by
which one signal can be selected from several
different video (or indeed audio) inputs. The
output of the bus is then sent to a specific
destination, such as a mix effects amplifier
(M/E), a Keyer, a DVE or the switcher output.
Traditionally, at least two buses are required
for even the simplest mix, wipe or key
operation. Buses often are labelled by letters:
A, B, C, etc. Also spelled ’’buss’’
See: Relief Mapping
Synonyms: Mixer Bus
Burst
Byte
A burst of chrominance signal with a phase
defined by the TV system specifications,
inserted in the line blanking intervals to provide
the reference for Subcarrier Synchronisation
1. A chunk of binary data containing eight Bits.
Sometimes known as an octet
2. A data word occupying the whole width of
the available bus, e.g. 8, 10 or 12 bits wide.
3. A data word containing all of the bits of the
sample of one channel, e.g. the luma byte
contains 8 bits or 10 bits per sample
Synonyms: Broadcast [TV] Standard
Build-Up Time
See: Rise Time
Bull’s Eye Pattern
See: Circular Zone Plate
Burst Blanking Sequence
A rule defining the specific line numbers in the
Vertical Blanking Interval on which the
Subcarrier Burst must be suppressed. In the PAL
system it is often called ’’Bruch blanking
[sequence]’’ (after Dr. Walter Bruch)
Burst Flag
C
See: Chrominance [Signal]
c/aph {cycles per active picture height}
Synonyms: BF; BG; Burst Key; Burst
The measure of the Spatial Frequency of a
periodic pattern in TV picture expressed as a
ratio of picture height to the period of the
pattern. It could be derived from tvl units:
frequency value expressed in c/aph is equal
to 1/2 of the frequency expressed in tvl, i.e.
’’288 c/aph’’ is the same as ’’576 tvl’’
Strobe
Camera Mode
An auxiliary sync pulse to provide correct
colour burst timing and blanking. It is normally
only found inside a piece of equipment and it
was distributed as part of the obsolete sevenwire drive system
Burst Key
See: Burst Flag
Burst Strobe
See: Burst Flag
Bursts
See: Explosion
Mode of vertical-temporal video signal
processing which assumes that odd and even
fields of the TV frame contain information from
different time moments, typical of interlaced
TV camera output
Caption Generator
See: Character Generator
Caption Key
A Key signal derived from a title source such as
a character generator
Synonyms: Title Key
12
Glossary
Capture Range
Central Control Room
Range of the input signal frequencies to which
a Phase Lock Loop (PLL) is able to lock. Once
locked the PLL generally has a greater input
frequency range known as Hold Range. The
term is similarly applicable to Genlocking SPGs
Area in the TV centre dedicated to routing
and switching functions
Synonyms: Pull-in Range
Centred Sweep
Castellation [of test pattern]
Alternating white and black boxes at the
perimeter of a test chart. Useful to test TV
picture positioning on the display screen, also
to observe picture cropping, display
registration, etc.
Synonyms: CCR; Master Control Room;
MCR
A variant of Line Sweep with the highest or
lowest frequency in the centre of TV line
(effectively a double sweep), hence the small
variations of the frequency response at this
central point are more visible
CG
CAV
See: Character Generator
See: Component Analog Video
Channel
CCD Telecine
Telecine device where the scanning is
achieved by the linear passing of film across a
single TV Line CCD sensor array. The complete
TV frame is built up in a suitable buffer store
Synonyms: Line Array Telecine
CCIR
French acronym for International Radio
Consultative Committee. One of the most
important organisations in the broadcast
television field, it has the status of the branch
of International Telecommunication Union
(ITU). In 1993 the CCIR was renamed to Radio
Branch of the ITU (ITU-RB) and later to Radio
Communication Sector of the ITU (ITU-R). The
crucial documents issued by CCIR are
Recommendations and Reports. They contain
information in very general form, often leaving
enough room for different variants of practical
implementation.
CCIR-656
See: Rec 656
CCR
See: Central Control Room
CCVS
See: Composite [Colour] [Video] Signal
1. Signal transmission or processing path
dedicated to specific signal or signal
component, e.g. ’’chrominance channel’’
2. A defined portion of frequency band
allocated for communication or broadcasting
service, e. g UK channel 21 occupies the band
from 470 to 478 MHz
3. Part of digital video effects device having its
own control parameters and dedicated to
manipulation of one TV picture, e.g. twochannels DVE is able to rotate one picture and
simultaneously squeeze another picture
Character Generator
Device used to generate text and simple
graphics for video titles or captions
Synonyms: Caption Generator; CG
CheckerBoard [Test] [Pattern]
Test pattern in a form of several bands with
alternating white and black boxes. This pattern
is useful to test geometry, registration, medium
and low frequency distortions
Chroma
See: Chrominance [Signal]
Chroma Bar
Test signal in a form of colour subcarrier
modulated by a bar signal, usually on grey
level pedestal
Synonyms: Modulated Bar
Chroma Blanking
See: Chrominance Blanking
13
Glossary
Chroma Crawl
Chrominance Staircase
See: Cross-Luminance
See: Multi-level Chroma Bar
Chroma Matte
CIE
See: Linear Chroma-Key
Noise in the chrominance channel. Visible as
randomly coloured spots on TV picture
French acronym for the International
Illumination Commission. An international
standardisation organisation that issues
documents defining the colorimetry of all
television systems
Synonyms: Colour Noise
Circular Zone Plate
Chroma Ramp
A Zone Plate pattern (circular or elliptic) with
lowest spatial frequency in the centre and
uniform rise of spatial frequency along any
radius, so that the spatial frequency is directly
proportional to the distance from the centre
Chroma Noise
Test signal in a form of colour subcarrier
modulated by a ramp signal, i.e. , the chroma
amplitude rises linearly along the TV line. This
signal is usually on a grey level pedestal
Synonyms: Chroma Sawtooth
Zone Plate
Chroma Sawtooth
Clamping
See: Chroma Ramp
Chroma-Key
A type of key where the hole-cutting
information is derived from a particular colour,
i.e. from a combination of the levels of at least
one primary or colour-difference component
of the video signal. There are many varieties of
chroma-key
extractors
of
different
performance and sophistication
Chrome
See: Chrominance [Signal]
Chrominance [Signal]
1. Modulated colour subcarrier signal
transmitted within composite signal or
separately
2. In general: Signal carrying the information
about colour hue and saturation, e.g. Cb/Cr
signal
Synonyms: C.; Chroma; Chrome
Blanking of chrominance signal. Usually the
chrominance blanking width is slightly shorter
than luminance blanking width
Synonyms: Chroma Blanking
Chrominance Phase Switching
SECAM
Switching
14
Chrominance
The process of resetting video signal level
offset to zero, for instance by using the Black
Level at the composite video Back Porch as a
reference
Synonyms: Back Porch Clamping; Black
Level Clamping
Coder
1. In general: Device performing an
’’encoding’’ function, e.g. an analog-to-digital
converter
2. Specifically: Composite colour video coder,
e.g. ’NTSC coder’’ or ’’SECAM coder’’, for
producing
Composite
Signals
from
Component Video sources
Synonyms: Encoder
Coding
See: Colour Encoding
Colorimetry
Chrominance Blanking
See:
Synonyms: Bull’s Eye Pattern; Fresnel
Phase
1. Literally means: measurement of colour
2. Specifically: Characteristics of colour
reproduction by colour television system or
device. In particular, it deals with the
chromaticity co-ordinates of CRT phosphors,
reference white colour, assumed gamma, etc.
Glossary
Colour Bars
Colour Encoding
One of the most popular test patterns,
containing several bars filled with primary and
complementary colours. There are many
variants of colour bars differing in the
sequence of colours, orientation, saturation
and intensity:
The standard colour bar sequence is
White/Yellow/Cyan/Green/Magenta/Red/Blue
/Black, it can be produced by simple 3-bit
counter. Typical specification of colour bar
levels (so-called bars nomenclature) is a set of
four numbers separated by slashes or dots and
giving RGB levels as a percentages of
Reference White as follows:
White_Bar/Black_Bar/Max_Coloured_Bars/Min
_Coloured_Bars.
For
instance,
the
nomenclature 100/0/100/25 means 100 % R, G
and B on white bar, 0 % R, G and B on black
bar, 100 % maximum of three R, G, B on
coloured bars and 25 % minimum of three R,
G, B on coloured bars. In this case
chrominance level is 100-25 i.e. 75 % . See: 100
% Colour Bars, 75% Colour Bars, EBU Bars,
SMPTE Bars
In broadcast TV: the transformation of primary
colour signals (or luminance and colour
difference signals) into Composite Video
Colour Corrector
Device processing video signals to correct for
colour errors (such as that introduced by
equipment during the production process or
incorrect lighting) and possibly to change
colours for artistic purposes
Colour Decoding
In broadcast TV: the transformation of
Composite Video into primary colour signals
(or luminance and colour difference signals)
Synonyms: Decoding
Colour Difference Signal[s]
Signals produced by matrixing primary colour
signals, in such a way that the signals become
equal to zero on reference white: e.g. R-Y, G-Y
or B-Y which are the red, green and blue
colour difference signals respectively. For
example R-Y is given by:
R-Y = 0. 701 R - 0. 587 G -0. 114 B
Note: there are many scaled, matrixed and
therefore
different
versions
of
colour
difference signals such as: I, Q; U, V; Pr, Pb; Cr,
Cb; Dr, Db which should not be confused with
basic colour difference signal
Synonyms: Coding; Encoding
Colour Field
TV Field numbered with reference to the start
of Colour Frame. E.g. in NTSC the colour frame
starts with colour field I and ends with the
colour field IV
Colour Frame
Set of several adjacent frames that begins
and ends with the same SCH value (NTSC and
PAL) or same colour difference signal type
(SECAM). Depending on the Colour TV System
it consists of:
NTSC 2 Frames ( 4 Fields)
PAL 4 Frames ( 8 Fields)
SECAM 2 Frames ( 4 Fields)
Note: If chrominance phase switching is taken
into account then one SECAM colour frame
consists of 6 Frames (12 Fields)
Colour Framing
TV Synchronisation providing Synchronism of
Colour Frames, usually for post-production
purposes. Modern VTRs do colour framing
automatically as part of run-in process. Lack of
colour framing will result in chroma flashes
after insert or assemble edits on some VCRs
Synonyms:
Colour
ID;
Colour
Identification; Colour Sync
Colour Fringing
Artifact of chrominance coding-decoding
process due to the limited bandwidth. It gives
the appearance of the colour not precisely
fitting the object defined by the luminance
signal
Colour ID
See: Colour Framing
Colour Identification
See: Colour Framing
15
Glossary
Colour Identification Signal
Colour Subcarrier Offset
Trapezoidal modulated super-saturated green
chrominance signals inserted on 9 lines of
vertical blanking interval in composite SECAM
signal
to provide colour synchronisation; not
recommended for further use, but still in use for
on-air broadcasting in some countries
Spectral position of Colour Subcarrier with
reference to the harmonics of line and field
frequency. Usually expressed as a ratio of
subcarrier frequency fsc to line frequency Fh.
For instance in the PAL system:
fsc=(1135/4 + 1/625) Fh
The first quotient in brackets determines a
coarse offset (also known as line offset), the
second quotient determines a fine offset (also
known as field offset or 25 Hz offset)
Note that the expression ’’Colour Subcarrier
Offset’’ is often used as jargon for the 25 Hz
offset alone
Synonyms: Bottles; Colour Sync [SECAM];
ID;
ID
[SECAM];
Identification
Signal
[SECAM]
Colour MultiPulse
A variant of
MultiPulse signal with filling
frequencies covering a range of frequencies
in the vicinity of the colour subcarrier,
designed to measure the chrominance
channel frequency response
Colour Noise
See: Chroma Noise
Colour Saturation
1. A psychovisual parameter defining the result
of the assessment of the apparent colour
difference from the achromatic colour (grey)
of same brightness
2. A colloquial expression used as equivalent to
the chrominance signal level or even to the
chrominance channel gain. As such can be
expressed as a percentage, e.g. ’’Saturation is
75 %’’.
Note: A red raster produced with 25 % level of
R signal and 0% levels of G and B signals would
be described by video engineers as ’’25 %
saturated’’ but psychovisually it is pure red and
therefore should be called ’’100 % saturated
red’’.
Synonyms: Saturation
Colour Subcarrier
Sinusoidal wave with frequency within
luminance signal spectrum which serves to
carry the information about colour hue and
saturation
Synonyms: SC
Colour Subcarrier Synchronisation
Expression to describe when two sub-carriers
are maintained in phase lock, usually with the
phase relationship adjustable for Genlock
purposes
Synonyms:
SC
Subcarrier
Colour Sync
See: Colour Framing
Colour Sync [SECAM]
See: Colour Identification Signal
Colour Timing
See: Subcarrier Timing
Colour Tint
1. A psychovisual parameter defining the
subjective decision of colour classification by
groups: ’’reds’’, ’’blues’’’, ’’yellows’’, etc.
2. An obsolete term used as equivalent to the
chrominance signal phase. This expression has
been replaced by ’’Hue’’
Colour TV System
A method of encoding a colour TV picture,
normally according to an agreed international
specifications. The three major world systems
are NTSC, PAL and SECAM.
Note: The Scanning Standard and other
parameters are only implied in these
descriptions so the full name for the broadcast
NTSC standard would be NTSC-M. For example
PAL-M and PAL-N are complete definitions for
the Broadcast Standards used in Brazil and
Argentina only
Synonyms: TV System
16
lock;
Synchronisation
Glossary
Comb [Filter]
Composite [Colour] [Video] Signal
Device using the periodic repetition of
chrominance subcarrier phases along the
vertical axis and sometimes the temporal axis
to
perform
luminance-chrominance
separation in the decoder. In the signal
frequency domain its response has a periodic
(comb-like) shape
Signal produced by summation of luminance,
synchronisation and chrominance signals, e.g.
PAL signal. Designed initially to achieve
optimal [encoded] single channel transmission
of colour TV picture information, by spectral
interleaving
of
the
luminance
and
chrominance signals
Comb Decoder
Synonyms: CCVS; CVBS
Decoder using Comb Filter[s] for luminancechrominance separation
Composite [Image]
Combiner [of DVE]
See: Mix Effects [Amplifier]
Compatibility
Ability of equipment designed for a particular
TV System to receive or process, with
acceptable quality, the signals of another TV
system. E.g. the reproduction of colour TV
signals by a black-and-white TV receiver. Not
to be confused with Multi-standard capability
Complementary Colour[s]
1. Colours which being added together give
white, e.g. blue and yellow are two
complementary colours.
2. Set of colours complementary to primary
Red (R), Green (G) and Blue (B) colours, i.e.
Cyan (Cy), Magenta (Mg) and Yellow (Ye)
Component Analog Video
General term for the handling of noncomposite colour signals in analog form.
Commonly used to describe parallel YPrPb
format
Synonyms: CAV
1. TV image produced as a result of mixing
and transformation operations with several
source images
2. Sometimes used to describe a complex and
often re-entrant multi-layering process with
many effects
Composite Blanking
Combination
blanking
of
horizontal
and
vertical
Synonyms: Mixed Blanking
Composite Pulse
Sum of Sine-Squared Pulse and a high
frequency
waveform
(usually
Colour
Subcarrier) which itself is modulated by the
same Sine-Squared Pulse. This signal serves to
check frequency response, group delay
response, and particularly Y/C gain and Y/C
timing errors
Synonyms: Modulated Pulse
Composite Sync
See: Synchronisation Pulses
Compositing
Component Signals
The action (and the art) of making a
Composite Image
See: Component Video
Compression
Component Video
See: Zoom-Out
1. Set of primary colour signals R, G, B or any
set of signals produced by reversible matrixing
of these signals, e.g. Y, Pr, Pb
2. In wider sense: any signal or set of signals
where luminance and chrominance spectra
are not frequency interleaved unlike
Composite Video. For instance, such signal
sets as Y/C, Y Dr/Db, or Multiplexed Analog
Component (MAC) signal, etc.
Synonyms: Component Signals
17
Glossary
Contrast
CRT
Ratio of brightness between any two areas of
TV picture
Cathode Ray Tube. One of the earliest
methods of visually displaying electronic
signals. CRTs are still by far the most common
display media and are employed in the
majority of television and computer diplays.
Ultimately they are likely to be diplaced by a
technology such as plasma or LCD. A CRT is a
thermionic valve and is a delicate piece of
equipment using very high voltages. They
should not be played with by the
inexperienced
Contribution
A form of video signal transmission where the
destination is not the ultimate viewer, and from
where some processing (e.g. in a vision mixer)
is expected before the signal reaches the
ultimate viewer
Convergence
See: Grid [Test] [Pattern]
Coring
A common video signal non-linear processing
operation which provides reduced gain for
low-level HF signal components which are
assumed to be mostly noise. The side effect of
this is that useful low-level HF signal
components are also attenuated, e.g. while
doing signal enhancement (which often
involves coring)
Coring Test [signal]
Test signal in a form of series of low level single
channel bowties, with different frequencies to
check the amplitude and frequency response
of Coring devices. This should not to be
confused with the ’’bowtie’’ timing test signal where the bowtie is the output of the device
under test, rather then the input signal
Synonyms: Noise Coring Test [signal]
Cr, Cb
Cr and Cb respectively, represent any red and
blue colour difference signals in the digital
domain only. For example, signals conforming
to Rec 601 contain Cr and Cb samples. In the
analog domain the same signals are denoted
by Pr and Pb.
CRC
See: Cyclic Redundancy Code
Cross Conversion
HDTV standards conversion involving both
frame and line rates, e.g. from 1125/60 to
1250/50. The expression Standards Conversion
is usually reserved for standard definition TV
Cross Planes
A multi-channel digital effect that causes the
displayed images to appear as though they
are put on several differently oriented planes
(usually intersecting one another)
Synonyms: Planes
Cross-Colour
Artifact in the chrominance channel due to
deficiency of Y/C separation in the decoder. It
consists of parasitic colour patterns on high
frequency luminance textures. E.g. the crosscolour Moiré pattern is coloured even if the
source picture is not - this may be caused by
the beating of the luminance frequencies
generated by, say, a tweed jacket, and the
colour subcarrier frequency
Cross-Fade
A vision mixer transition where the video from
the A-Bus dissolves out while the B-Bus video
dissolves or '
mixes'in, hence the name '
'
A-B
Mix'
'
. The amount that one particular bus video
predominates is determined by the relative
position of the mixer fader arm, i.e. , when the
fader arm is all the way toward the A-Bus side
then only the A-Bus video appears at the
output
Synonyms: A-B Mix; Mix
18
Glossary
Cross-Luminance
Cyclic Redundancy Code
Artifact in the luminance channel due to
deficiency of Y/C separation in the decoder. It
looks like parasitic dots at the sharp or moving
edges of saturated coloured objects
A standard error-detection code used to
check the presence of bit errors in a block of
data
Synonyms: CRC; Cyclic Redundancy
Synonyms: Chroma Crawl; Dot Crawl; Check
Moving Dots
D/A
Crosshatch
See: Digital-To-Analog Converter
See: Grid [Test] [Pattern]
Crosstalk
General term for unwanted component in the
signal due to deficiency of channel
separation in a multi-channel system. Crosstalk
level may also be given and measured in dB
with reference to either an interfering or
wanted signal, e.g. ’’crosstalk is less than minus
46 dB at 5 MHz’’
Crystal Locked Subcarrier
See: Free-Running Subcarrier
Cube
A digital effect that causes the displayed
image to appear as if it is mapped onto the
surfaces of a cube. The multi-channel variant
of this, is where each surface displays a
different image
Cut
An instantaneous transition during the vertical
blanking interval, so the viewer sees the new
picture immediately after the transition was
triggered. In standards conversion (particularly
high quality 4-field) cuts present a serious
problem since the cut will effectively emerge
spread over four fields (like an unwanted
cross-fade). In the proprietary Snell & Wilcox
’’Clean-Cut’’ technique cut spread is
eliminated and the resultant conversion has
cuts as sharp as the source material
D1
Component digital recording format on 19
mm magnetic tape. The term is often
incorrectly used as a generic term instead of
4:2:2 or Rec. 601
D1- D2 Bridge
See: D1-D2 Converter
D1-D2 Converter
Professional jargon nickname for a device
converting video
signals
from
digital
component 4:2:2 format to 4fsc digital
composite format
Synonyms: D1- D2 Bridge
D2
Composite digital recording format on 19 mm
magnetic tape. It exists in three versions: for
NTSC, PAL, and PAL-M systems. The term is
often incorrectly used as a generic term
instead of 4fsc digital composite
D2 - D1 Converter
Professional jargon nickname for a device
converting video signals from 4fsc digital
composite format to digital component 4:2:2
format
Synonyms: D2- D1 Bridge
D2- D1 Bridge
See: D2 - D1 Converter
CVBS
See: Composite [Colour] [Video] Signal
Cyclic Redundancy Check
See: Cyclic Redundancy Code
19
Glossary
D3
DCT
A tradename for 4fsc composite digital
recording format on 13 mm (1/2") magnetic
tape. It exists in three versions: for NTSC, PAL,
and PAL-M systems. D3 has minor interface
differences with D2 equipment
1. Abbreviation for Discrete Cosine Transform,
a mathematical technique, similar to the
Fourier Transform, used in a variety of signal
processors
2. The Ampex tradename for a component
digital tape recording format with signal
compression. At the interface level it is
compatible with the D1 format i.e., it conforms
to Rec. 656.
D5
A tradename for a component digital tape
recording format. It exists in two versions: with
13.5 MHz sampling rate (same as D1) and 18
MHz sampling rate, sometimes referred as D5H
and conforming to Rec. 601 B
DAC
See: Digital-To-Analog Converter
Data Bus
A
set
of
(normally
parallel)
digital
interconnections
between
modules,
electronic chips or circuit boards
Synonyms: Digital Bus
Data Line[s]
Generic term for coded pulse sequence
inserted in one or more lines of the vertical
blanking interval for data transmission, not
necessary related with TV broadcasting, e.g.
Teletext or Closed Captioning
Data Packet
Fixed-length self-contained block of data that
includes all relevant header information to
allow switching, routing and data recovery
Synonyms: Packet
De-interlacing
1. Up Conversion where the number of lines
per frame and Frame Rate are preserved, but
the interlace ratio is modified, usually from 2:1
to 1:1
2. Intermediate stage of standards conversion
to alleviate the frame rate conversion. Not
normally found as a discrete stage and
assumed only in theory
De-serialiser
See: Serial-To-Parallel Converter
Decimation
A simple variant of down-sampling achieved
by discarding information, for instance by
using only every other sample of video data (2
times decimation). Decimation can bring
aliasing problems if not accompanied by
appropriate pre-filtering
Decoder
1. In general: Device performing a ’’decoding’’
function, e.g. a digital-to-analog converter
2. Specifically: Composite colour video
decoder, e.g. ’’NTSC decoder’’ or ’’SECAM
decoder’’, for producing Component Video
from Composite Signals
Decoding
See: Colour Decoding
20
Glossary
Definition
Digital
Ratio of Contrast of fine periodic textures to
the contrast of the coarse periodic textures in
the TV picture, usually at some specified
Spatial Frequency, e.g. definition is 10 % at 400
tvl. This parameter is related to so-called
’’modulation depth’’ which describes the video
signal produced by an electro-optical sensor
device
Used to describe the “modern” system of
signal processing where a signal level is
represented by a number in a computing
system. Unlike Analog systems, Digital systems
only have a discrete number of different levels
to represent the signal of interest. The longer
the digital word the more accurate the
representation will be. For instance, an 8-bit
binary signal can have 256 different levels
whereas a 16-bit signal can have 65536
different levels. The great advantage of digital
signals is their ease of processing by modern
microprocessor based engines, and the fact
that the signals may be transmitted, recorded
and reproduced over several generations,
with no loss of accuracy whatsoever. Bear in
mind however, that it is an analog world out
there and digital signals must always be
created from analog inputs, and similarly
converted to analog outputs (such as light
and sound) so we humans can do something
with them.
Defocus
Optical or digital effect where the whole
frame of video or some part of it appears to
be significantly blurred (defocused). For
instance a single white pixel will spread
gradually over several of its neighbours. Similar
to, although not the same as ’’antialising’’
Desaturation
A digital video effect where the gain of colour
difference signals is reduced to produce less
saturated
or
completely
desaturated
(monochrome) pictures
DG
Digital Active Lines
See: Differential Gain
Change of the chrominance amplitude (i.e.
chrominance gain) as function of luminance
level
Lines of the TV frame carrying digital picture
information, i.e. all frame lines except the
vertical blanking interval. Normally the number
of digital active lines is greater that the
number of analog active lines.
Synonyms: DG
Digital Active Part [of TV Line]
Differential Gain
Differential Phase
Change of the chrominance
function of luminance level
Synonyms: DP
phase
as
Same as Analog Active Part with the addition
of a few pixels before and after to prevent the
distortion of analog active part information
caused by digital filtering
Digital Audio Frame
Packet of data, containing quantized value of
one sample of audio signal and related
auxiliary data. Usually includes two sub-frames
to carry one sample of two audio channels,
e.g. stereo audio
Digital Betacam
Sony'
s tradename for a component digital
tape
recording
format
with
signal
compression. At the interface level it
compatible with D1 format, i.e. it conforms to
Rec. 656. Note that some Digital Betacam
machines will record and playback analog
Betacam SP tapes
Digital Bus
See: Data Bus
21
Glossary
Digital Compression
Digital Video Disk
The processing of sampled digital signals in
order to reduce their bit-rate (the number of
bits per second) so that they may pass through
a lower bit-rate capacity channel. Hence in
TV terms it means the processing of digital
component signals to reduce the required
transmission or recording channel capacity
with minimal loss of TV picture quality
The digital data storage system using 120 mm
optical disk. With 4.7 gigabytes of storage
capacity on a single layer and 8.5 gigabytes
on a dual-layer disc, DVD-ROM offers more
than 12 times the capacity of CD-ROM. DVDROM drives are able to play the existing CDROMs. Reference DVD user data rate is 1.108
Mbytes/sec. At the nominal "average" MPEG2
compressed video data rate of 3.5 Mbit/sec,
this still leaves enough capacity for discrete
5.1-channel digital sound in three languages,
plus subtitles in four languages. Including
video, audio and subtitles, the total average
data rate is 4.962 Mbit/sec, hence a singlelayer DVD can hold a two hour, 13 minute
video programme
Synonyms: Bit Rate Reduction; Signal
Compression
Digital Serial Component
Serial digital video interface format where
component Y, Cr, Cb signals are transmitted
at 270 Mbit/s or 360 Mbit/s rate
Synonyms: DSC
Digital Video
Consumer digital compressed video recording
format with 10-micron tracks on 6.35 mm (1/4")
metal tape
Synonyms: DV
Digital Video Broadcasting
The Digital Video Broadcasting (DVB) project
was formally inaugurated in September 1993.
It is a voluntary grouping of over 200
organisations from both the private and the
public sectors in 25 countries around the
world. Its aim is to agree systems for digital
television
broadcasting
using
MPEG2
compression. DVB allows users better use of
common components whatever the media
transport - satellite, terrestrial, cable, or satellite
master
antenna
TV.
DVB
standards
complement MPEG standards by defining the
modulation and scrambling methods for each
application separately.
Synonyms: DVB
Synonyms: DVD
Digital Video Effect [Device]
The traditional definition is a device to perform
video effects by digital means, either including
built-in mixer or connected to external mixer to
enhance its artistic features. More modern
jargon usage takes DVE to mean a two or
three-dimensional special effects generator,
without mixing facilities
Synonyms: DVE
Digital-S
JVC’s tradename for digital compressed video
tape recording format using 20-micron tracks
on 13 mm tape. Digital-S machines at the
interface level conform to Rec. 656 and can
play back analog S-VHS tapes
Digital-To-Analog Converter
1. In narrow sense: A device (usually, a microchip) which transforms a signal from digital
form to analog form. This is done by conversion
of binary codes into analog signal values and
holding these signal values during sampling
interval.
2. In wider sense: Device performing all
functions, necessary to convert incoming
digital video signals with a specified digital
interface format, into analog video signals
with a specified analog interface format, in
particular,
serial-to-parallel
conversion,sampling frequency recovery,
video signal post-filtering, and even sync pulse
insertion
Synonyms: D/A; DAC
22
Glossary
Digitisation
Double Re-Entry Mixer
Professional jargon word for analog to digital
conversion
A Vision Mixer with two Mix Effects buses,
where the output of one can be fed into the
other (re-entered) as a separate input. This
allows more layers of processing to take place
in a single pass through the system
Display
Process of sequential [in time] transformation
of electrical signals into colour or brightness of
an image
Synonyms: TV Synthesis
Display [device]
Device for transformation of electrical signals
into variations of colour or brightness in a
viewable image
Synonyms: Display device
Synonyms: Two Stage Mixer
Down Conversion
Standards conversion where the Line Rate of
the output standard is significantly lower that
of the input standard, e.g. 1125/59.94 to
525/59.94
Down-Sampling
See: Display [device]
Sampling Rate Conversion to decrease the
sampling rate, e.g. from 17.732 MHz to 13.5
MHz
Display Up Conversion
Down-Stream Keying
Display device
Up Conversion for display purpose only; usually
to reduce the display artifacts, such as Visibility
of Line Structure, Large Area Flicker and
Interline Flicker
Distribution
The process of bringing a TV signal to the
ultimate
viewer,
possibly
via
some
intermediate
points
or
stages.
Radio
Frequency emission of a TV Signal is an
example of a distribution stage but not the
complete chain
DO
See: Drop-Out [Control] Pulse
DOC
See: Drop-Out [Control] Pulse
Dot Crawl
See: Cross-Luminance
Keying in a vision mixer that electronically
appears after all other operator functions. Any
operations performed on the mixer M/Es will
not affect the downstream key video, hence
any signals (e.g. captions) inserted at this
point, are always in the foreground
Synonyms: DSK
DP
See: Differential Phase
Dr, Db
Colour difference signals scaled to provide
necessary SECAM chrominance frequency
deviations:
Dr = -1.902 (B-Y)
Db = 1.505 (B-Y).
Dr/Db Switch
See: 2H
Double Mirror
A digital effect where the displayed picture
appears as though split by an imaginary line,
one side having the original image and on the
other side of the split is a complementary
Mirror image
Synonyms: Symmetry
23
Glossary
Drop Shadow
DVCPRO
A mixer and digital effects keyer function that
gives the Foreground Key video the
appearance of having a separate shadow (as
opposed to an extruded shadow which would
have no gaps between object and shadow).
This function is often used with titling. Some
characteristics of this shadow, such as size and
position, are often adjustable. Note that the
expression ’’drop shadow’’ is often used to
describe an extruded shadow
Tradename for digital compressed video tape
recording format. DVCPRO equipment is
backward compatible with consumer DV
tapes, but has a wider 18-micron heads,
higher tape speed and use azimuth recording.
Control
track tape speed is 33.8 mm/s. Sampling
format is 4:1:1, which means that sampling
frequencies are: Y -13.5 MHz, Pr/Pb - 3.375
MHz. Quantization resolution is 8 bits/sample
Drop-Out [Control] Pulse
DVD
A signal input to a Drop-Out Compensator
which causes the drop-out compensation to
be performed for the entire duration of the
pulse. Normally this pulse is derived from the
absence or drop in level of the modulated FM
carrier emerging from the video head
amplifiers
See: Digital Video Disk
Synonyms: DO; DOC
Drop-Out Compensator
Device for concealment of small erroneous
fragments of video (drop-outs), e.g. errors
produced because of defects, dirt or wear in
magnetic recording media. Once detected
these erroneous fragments are replaced by
non-corrupted signal from spatially or
temporally adjacent areas of TV picture
DSC
See: Digital Serial Component
DSK
See: Down-Stream Keying
DV
See: Digital Video
DVE
See: Digital Video Effect [Device]
Dynamic Resolution
Resolution when there is a movement in the TV
picture, e.g. when camera is zooming or
panning
Synonyms: Motion Resolution
EAV
End of Active Video. A code word, marking
the end of the Digital Active Line in
component digital systems
EBU
European Broadcasting Union. A regional
broadcasters’ union that was initially a Western
European body. In 1993 merged with the
Eastern European International Radio and
Television Organisation (OIRT). The EBU issues
EBU Technical Recommendations, which are,
in fact, almost mandatory for its members
EBU [Colour] Bars
Colour Bars with the nomenclature 100/0/75/0
DVB
Edge
See: Digital Video Broadcasting
See: Border
DVCAM
Edge Time
Sony’s tradename for professional version of
the consumer DV format
See: Rise Time
EDH
Error Detection and Handling. A system of error
detection and error rate assessment using
insertion of CRC code words in the digital
video stream
24
Glossary
Editor Interface
Electronic News Gathering
A feature that permits some or all mixerswitcher functions to be controlled from an
external device. Editor interfaces may be
serial, as in RS-422 or parallel as in the GPl
Production and post-production of TV news
programmes,
usually
with
hand-held
camcorders and other portable equipment
EDTV
ENG
See: Extended Definition Television
Electronic Test Chart
EDTV II
Test pattern created by electrical means;
unlike test matrix often contain twodimensional components like circles, etc.
Second generation Japanese widescreen
EDTV system
Effects Loop
A Vision Mixer feature where an M/E has an
output that allows video to be sent to external
devices (e.g. a DVE) and then returned to the
mixer for more processing
Effects Memory
A computer style sub-system capable of
storing mixer or DVE panel settings and
possibly sequences which may later be
recalled to exactly duplicate an effect
EFP
See: Electronic Field Production
EIA [Colour] Bars
Synonyms: EJ; Electronic Journalism;
Synonyms: Frame-based Test Pattern
Elementary Stream [MPEG]
A coded MPEG bitstream for one programme
of audio or video, or one data stream. A
Packetized Elementary Stream includes time
stamps and header information
Embedded Audio
Method of transmitting a digital video signal
together with accompanying (multichannel)
sound by way of insertion of audio data
packets in the digital video stream
Encoder
See: Coder
Encoding
A Test Matrix pattern which consists of the
following:
75 % of the field is occupied by 75 % Colour
Bars with bar eight missing (i.e. without Black)
The remaining 25 % shows a sequence of -I,
White, Q and Black
This pattern is a simpler version of the SMPTE
Bars
See: Aperture Correction
EJ
Equalising Pulse
See: Electronic News Gathering
Elastic Sheet
A particular kind of Warp where the output
picture looks as though it were mounted on an
’’Elastic Sheet’’ which may be distorted as
stretched and pulled out of shape as required
Electronic Field Production
See: Colour Encoding
ENG
See: Electronic News Gathering
Enhancement
A pulse within vertical sync group, narrower
than line sync pulse. E.g., in 625 line signals the
H-Sync pulse has a width of 4.7 microseconds
and the equalising pulse width is 2.35
microseconds. Together with Broad Pulses they
form the Vertical Sync Group
EUREKA
Synonyms: EFP
European new technologies development
project
under
whose
guidance
the
1250/50/2:1 HDTV system was created - hence
the name is often identified with the system
itself
Electronic Journalism
Even Field
See: Electronic News Gathering
Field with even number in the interlaced field
sequence
Production of TV programmes outside the
confines of a specially equipped production
centre
25
Glossary
Expand
Field Alias
See: Zoom-In
A digital video effect in which an object
appears to be split into a stream of particles
emerging pseudo-randomly from the centre
of an object
Artifact of interlaced television raster display
due to coarse line pitch and low field rate.
Visible as either Interline Flicker (fast changes
of brightness) or Interline Twitter (vertical
hopping at frame rate on fine vertical detail or
textures) depending on relative phase of line
structure and vertical detail
Synonyms: Bursts
Synonyms: Interline
Extended Definition Television
Flicker
Television with definition improved with
reference to conventional TV at least in one of
two (vertical and horizontal) dimensions
Field Blank
Synonyms: EDTV
Field Blanking
External Key
See: Vertical Blanking
Keying mode where the key video is a
separate signal connected to a dedicated
input of the mixer (or DVE). This signal is usually
supplied by the same device that created the
fill video, e.g. a character generator or DVE
Field Comb [Filter]
Explosion
False Colours
A digital video effect where the colour palette
is re-mapped, for instance causing green to
become magenta and magenta to become
blue, etc.
FCC
Federal Commission of Communications.
Regulatory body of the US Government
FCC Composite
Vertical Interval Test Signal specified by FCC
for the NTSC system. Similar to VITS test line
CCIR-330
Twitter; Interline
See: Vertical [Blanking] Interval
Comb Filter using inputs from one or more
spatially adjacent lines in at least two
adjacent fields
Field Datum
In 525 lines system: A reference time moment
given by the Line Datum coincident with the
beginning of the first equallizing pulse in the
vertical sync group.
In 625 lines system: A reference time moment
given by the Line Datum coincident with the
beginning of the first broad pulse in the
vertical sync group.
Commonly accepted as a timing reference
point
for
colour
framing
and
SCH
determination. See also Frame Datum
Field Doubling
Vertical Interval Test Signal specified by FCC
for the NTSC system. Similar to VITS test line
CCIR-18
Simplified variant of frame rate up conversion
where every other field of the output signal is
merely a copy of the previous one, usually for
display purposes to reduce the Large Area
Flicker
FD
Field Drive
See: Vertical Drive
See: Vertical Drive
Fh
Field Frequency
See: Line Frequency
Number of [TV] fields transmitted per second
FCC Multi-burst
Synonyms: Field Rate; Fv
Field Rate
See: Field Frequency
Field Sag
See: Field Tilt
26
Glossary
Field Scanning
Figure
See: Vertical Scanning
Wipe with closed contour, e.g. a ’’star’’ or
’’diamond’’
Field Square Wave
A simple black and white test pattern with the
upper 50 % of the screen occupied by
horizontal white bar and the remaining area
by black. This pattern serves mainly to
measure low frequency distortions, but is useful
for other measurements, e.g. for level
dependent noise or hum suppression device
performance
Field Sweep
Sweep signal with the frequency incremented
along a TV field. Odd and even fields are
usually identical.
There are two different kinds of field sweeps.
The sweep frequency usually rises from top to
bottom, and may be fixed or variable from left
to right. In the first case the line-to-line phase
relationship of the sweep waveform is
constant (at a given point on the TV line),
giving a pattern with a visible structure that
contains elements with horizontal, diagonal
and vertical
spatial frequencies. In the
second case the phase relationship is
effectively random. Hence the on-screen
pattern varies correspondingly
Field Sync Pulses
Group of several adjacent broad pulses (6 in
525 lines system or 5 in 625 lines system).
Field Tilt
Tilt measured across the top of the bar in a
horizontal Bar test signal. Measurement is
along the vertical axis using a waveform
monitor. Field Tilt is a result of low frequency
distortions, e.g. deficiency of clamping
Synonyms:
Field
Sag;
Field
Film Grain
Artifact of cinematographic production due
to the finite size of film emulsion grains,
especially with high sensitivity film stocks
Synonyms: Grain; Granularity
Film Mode
Mode of vertical-temporal video signal
processing which assumes that odd and even
fields of the TV frame contain information from
the same time moment, typical of film and
consequent film to video transfer
Firewire [Digital Interface]
Some semi-professional and all new consumer
compressed digital video products are
equipped with the "Firewire" digital interface
(also known as IEEE1394 or P1394). The special
multiwire cable length in this case is limited to
4.5 m and the video rate is approximately 30
Mbit/s. Converters are available to transform
Firewire data into standard Rec 656 SDI format
and vice versa
Flat Colour
A simple Test Pattern in the form of a colour or
grey level background (e.g. 75 % Red Field).
The Flat Colour Fields are useful to check CRT
colour purity, or Hanover bars in a decoded
PAL picture
Synonyms: Flat Field
Flat Field
See: Flat Colour
Time
Distortion
Field Time Distortion
See: Field Tilt
27
Glossary
Flicker
Flo-Mo
Both motion picture and television systems
represent the real world (in which time is
continuous and unbroken) by a series of
discrete instantaneous slices or samples. These
samples are then replayed one after the other
for viewing. The snag is that will be gaps
between one image and the next. If this gap is
too long, it will be visible as flicker. In European
PAL television the field rate is 50 Hz and the
resultant flicker is highly objectionable to
viewers accustomed to 60 American field
rate. In motion pictures shot at 24 frames per
second, flicker would render the images
unusable if viewed at the same refresh rate.
The ruse used in theater projectors is to “flash”
each image 3 times, giving an effective frame
rate of 72 Hz
A proprietary Snell & Wilcox Slow-Motion
system based on Phase Correlation. Instead of
merely playing the original footage slower and
thus jerkily because of field or frame repetition,
the intermediate '
'
tweens'
'are computed in
real time using motion compensation
techniques and no fields or frames are
actually repeated
Flip
A combination of gradual horizontal Squeeze
and Mirror effects that cause the displayed
picture to appear as rotating about itsvertical
axis
Flip-Flop Bus
A mixer-switcher bus configuration where the
video selected on one bus of the mixer is
immediately transferred to the other bus at the
completion of a transition. This type of bus is
often associated with the Programme Bus and
Pre-set Bus of a mixer, the advantage being
that the same bus of the mixer always
determines what source is on air. If the
Programme and Pre-set buses are not the FlipFlop type, the bus indicating the source on air
depends on which one the associated fader
bar is pointed to
Floating Mode [of Time Base Correction]
A special mode of Time Base Correction in
which the long-term time reference is derived
from the incoming signal itself, but short term
instabilities are removed so that the signal
becomes useful with some timing-sensitive
devices
Flying Spot Telecine
Telecine device where the scanning is
achieved by movement of a bright spot on a
CRT screen. The resultant scanning '
'
patch'
'is
projected onto the film frame, the total light
passing through the film being measured by a
single light-sensitive device (or three for RGB)
Footprint
1. Hole made in the mud by your boots
2. Professional jargon for the effect of
interaction
between
remaining
CrossLuminance in a composite signal and newly
introduced chrominance signal, due to
incomplete chrominance removal at the
previous stage of decoding, e.g. in case of
PAL-PAL or PAL-SECAM transcoding it should
be called '
'
PAL footprint'
'
Foreground [Video]
The video that fills the hole cut by the keying
circuits. Fill video does not necessarily have to
be related to the hole cutting signal. For
instance, the hole cutting signal may be
obtained from a character generator, while
the video to fill it is obtained from a video
camera
Synonyms: Key Fill
28
Glossary
Format [of the video signal interface]
Frame Rate Conversion
Video signal interface specification covering
number of signals, physical interface
parameters, pinouts, signal levels, polarities,
etc.
Conversion of video signals from one Frame
Rate to another, usually preserving the number
of lines per frame
Format [of video recording]
Scanning producing TV frames (and fields in
case of interlacing)
Video signal recording specification covering
the physical record media parameters, track
layout, tape speed, etc. For example, ’’VHS’’ is
a magnetic video tape [cassette] recording
format
Format Conversion
Generic term to describe any transformation
from one video format to another, e.g. from
serial digital component video to serial digital
composite video. This term is often used
informally
to
imply
that
an
encoding/decoding process is taking place
Frame Blanking
See: Vertical Blanking
Frame Datum
A reference time moment given by the Line
Datum coincident with the beginning of the
first equalising pulse (525 lines standard) or with
the beginning of the first broad pulse in the
vertical sync group (625 lines standard).
Commonly accepted as a timing reference
point
for
colour
framing
and
SCH
determination
in
625 lines standard. Field Datum is actually an
inappropriate term - the reference point is only
a Frame Datum
Synonyms: 0v
Frame Scanning (informal usage)
See: Vertical Scanning
Frame Synchroniser
A device performing variable delay function
from minimal up to one whole frame, for the
purpose of Synchronisation. Slight differences
between the frame rates of incoming and
reference
signals
can
usually
be
accommodated.
Note that if the incoming and reference frame
rates are different then occasional fields must
be added or dropped, which can cause
visible jumps. It is for this reason that not only
VTRs, but even VCRs, are often field-locked, to
zero the long-term frame rate difference
Frame-based Test Pattern
See: Electronic Test Chart
Free-Running Subcarrier
A colour subcarrier with stable frequency but
without
guaranteed
constant
Colour
Subcarrier Offset. It could be produced by
semi-professional equipment, such as an S-VHS
VCR
Synonyms: Crystal Locked Subcarrier
Freeze
Frame Frequency
Number of [TV] frames transmitted per second
Synonyms:
Frame Scanning
Frame
Rate;
Vertical
Frequency (informal usage)
Frame Grabber
Device to acquire (grab) and store a single TV
frame from the input video signal. It is normal
to be able to select either field (repeated) or
the entire frame as the output of the device
1. Rather obviously , this is a digital effect
where the displayed picture appears as if the
live video sequence is suddenly stopped
2. A momentary repeat of one TV frame or
field from the live video sequence, usually
caused by temporary loss of synchronisation.
This is more usually called Panic Freeze
Frequency Response
See: Gain vs. Frequency Response
Frame Rate
See: Frame Frequency
29
Glossary
Front Porch
Gamma
Part of the composite video signal within the
time interval from start of the line blanking
interval to the the leading edge of the line
sync pulse. In 625 line and 525 line systems the
front porch duration is 1.5 microseconds
A parameter describing the curve of
amplitude
response
(level
response)
according to the expression: gamma =
log(Y)/log(X).
It is usually expressed as a ratio of logarithms of
output and input signals; e.g. the assumed
colour CRT display gamma is 2.8 which
indicates
that
the level of light output is not linearly
dependent on the input video signal level. In
this case 50 % grey signal gives less than 20 %
light output. It is for this reason that gamma
correction is applied in video cameras - from
then onwards the TV Signal is assumed to be
Gamma Corrected.
Note that computer generated signals are not
usually gamma corrected which may give rise
to problems
Full Frame Test Signal
Test signal present in Active Parts of all Active
Lines of the TV Frame (as opposite to VITS)
Fv
See: Field Frequency
Gain vs. Frequency Response
A common measure of video or audio signal
path performance where a gain is plotted
against frequency. Usually plotted in decibels
(dB) over a given frequency range. Sometimes
phase or delay vs frequency responses are
optionally
added
to
provide
better
representation. Tolerances of frequency
response are often quoted for circuits in dB,
this being the deviation from an assumed
ideal curve (usually from horizontal line, i.e.
from
"flat"
response).
The
expression
’’frequency response’’ is often incorrectly used
instead of Bandwidth
Synonyms: Frequency Response
30
Generations
The number of times a segment of video
programme has passed through equipment
where any part of it was either re-encoded or
re-recorded
Glossary
Genlock
Grid [Test] [Pattern]
A mode of Synchronisation in which a device
is made to synchronise with an incoming
reference signal provided by another device,
e. g station reference Pulse Sync Generator.
For composite signals there are two main
functions of genlocking: vertical and horizontal
sync locking plus SC Lock. Traditional genlock
devices allow independent adjustment of HTiming and SC phase. The output SCH phase is
normally adjustable through 360 degrees thus
allowing correct chroma timing, but usually
sacrificing zero SCH requirement of new digital
composite equipment. A modern alternative is
to generate fixed (usually zero) SCH phase
and sacrifice H sync timing accuracy to
achieve chroma timing. Note that the fixed
SCH genlock only works with mathematically
accurate reference
Test pattern which consists of white lines on
black background or black lines on white
background forming a grid. This pattern serves
to check the registration (convergence)
quality of colour displays
Geometry Effects
Group Of Pictures [MPEG]
Digital video effect that transforms the objects
geometry, e.g. squeezing it diagonally, or
altering it into the shape of a sphere
Specific segment of MPEG video bitstream.
From time to time, an entire spatially
compressed input picture needs to be sent by
MPEG encoder to the decoder, with no
prediction involved. These are I (intra) pictures.
Some other pictures are predicted from past
information, these are P (predicted) pictures.
The P frame uses the nearest previous frame (I
or P) on which the forward prediction is based.
Pictures between I and P pictures can be
predicted from past and future information to
give a better prediction. These are B (bidirectionally predicted) pictures. B frames are
not used as reference frames for further
predictions. I, P and B pictures go together to
make a Group Of Pictures
Global
Term used in digital effects to describe the
ability to apply additional manipulations to
keyframes with previously stored digital effects
GOP
See: Group Of Pictures [MPEG]
Graduated Matte
Variant of Background with a gradual change
from one colour to another across the picture
Synonyms: Wash
Synonyms: Convergence; Crosshatch
Group Delay
Common measure of phase response given
by the derivative of phase vs. frequency
response, i.e. a linear phase response
differentiates to a constant group delay
response, which in turn means a fixed overall
delay for all frequency components (an input
signal will not be distorted but merely delayed
by the group delay). Group delay is usually
specified in nanoseconds (ns) as a
counterpart of gain vs. frequency response
Grain
Synonyms: GOP
See: Film Grain
Guard Band
Granularity
See: Film Grain
Grey Scale
A test pattern in the form of a luminance
staircase (increasing
or decreasing ).
Commonly used to check the display’s
dynamic grey balance (grey scale tracking)
1. The gap between tracks (if any) on a
magnetic or other recording media.
2. The gap between adjacent frequency
channels in a multichannel system
3. Difference between reference black level
and blanking level in the luminance signal.
Relevant only for NTSC (USA) and PAL-M
systems, in all other systems there is no
difference, so reference black is set at
blanking level. Note that NTSC as used in
Japan has zero guard band
H-Sync
See: Line Sync [Pulses]
31
Glossary
H-Timing
HDVS
See: Horizontal Timing
See: High Definition Video System
Hall of Mirrors
Helper [Signal]
A recursive effect involving multiple re-entry of
images into a
mixer/combiner.
Most
commonly seen as the image repeated many
times disappearing into infinity, usually
reducing in contrast on the way
Modulated subcarrier signal carrying the
vertical detail information lost in the process of
aspect ratio conversion and transmitted in
black bands below and above the letterbox
picture in some widescreen TV systems. The
helper signal is designed to be practically
invisible on the screen of a conventional
receiver
Hanging Dots
Cross-luminance
near
sharp
saturated
horizontal coloured edges, e.g. at the
boundary between bars and red field in the
Bars And Red pattern
Hanover Bars
Artifact of PAL coding-decoding process due
to incorrect Subcarrier Synchronisation. It is
visible on saturated large areas in a TV picture
(particularly reds) as a change of hue on
alternate TV Lines in a PAL-simple decoder or
as change of saturation on alternate TV Lines
in a PAL-delay decoder
Hi-Vision
Sony’s trademark for an 1125/59.94/2:1 HDTV
system with parallel analog component
interface
Hierarchical Spatial Correlation
Synonyms: Venetian blinds
Multi-stage form of Block Matching method of
motion compensation starting with large
blocks to avoid false matches and then
subdividing the block sizes to produce a
motion vectors more accurately and with
higher spatial resolution
Hard Boundary
High Definition Television
See: Hard Wipe
Hard Edge
See: Hard Wipe
Hard Key
Key signal extraction with relatively high gain.
It produces sharp, hard edges that tend to
make the foreground look like it is ’’pasted’’ on
top of the background. The edges in case of
self-keyed noisy live video sources are rather
poor because a hard key cannot generate a
satisfactory key switching signal with video
that does not have extremely sharp transitions
from black to white
Hard Wipe
Variant of Wipe with sharp boundary between
background and foreground areas of TV
picture
Synonyms: Hard Boundary; Hard Edge
HD
See: Horizontal Drive
HDTV
See: High Definition Television
32
Television with definition approximately
doubled with reference to the conventional
TV both vertically and horizontally and with
increased picture aspect ratio
Synonyms: HDTV
High Definition Video System
Japanese broadcaster NHK"s trademark for an
1125/59.94/2:1 HDTV system with parallel
analog component interface
Synonyms: HDVS
Hold Range
Range of the input signal frequencies to which
a Phase Lock Loop (PLL) is able to maintain
lock. Before lock is achieved the PLL generally
exhibits a smaller input frequency range
known as Capture Range. The term is similarly
applicable to Genlocking SPGs
Horizontal [Blanking] Interval
Time interval during which horizontal blanking
is applied. E.g., in 625/50/2:1 line systems the
Horizontal Blanking width is 12 microseconds
Synonyms: Horizontal Blank; Line Blank
Glossary
Horizontal Blank
I, Q
See: Horizontal [Blanking] Interval
Synonyms: HD; LD; Line Drive
Colour difference signals scaled and matrixed
to provide necessary NTSC chrominance:
I = - 0.2680 (B-Y)+0.7358 (R-Y)
Q = 0.4127 (B-Y)+0.4778 (R-Y)
A historic note: I was always supposed to be
full bandwidth 1.3 MHz, as opposed to Q
which
had
a reduced bandwidth of 0.4 MHz. The present
situation is that I and Q are equiband in socalled ’’Studio NTSC’’ although the on-air
specification is still as it was.
Horizontal Scanning
ID
Scanning producing TV lines, i.e. scanning in a
horizontal direction
See: Colour Identification Signal
Horizontal Blanking
Line rate Blanking
Synonyms: Line Blanking
Horizontal Drive
Sync pulse with leading edge marking the start
of Horizontal Blanking Interval. Sometimes
incorrectly called ’’Horizontal Sync’’
Synonyms: Line Scanning
Horizontal Screen Occupation
Ratio of active image area width to the
display screen width
ID [SECAM]
See: Colour Identification Signal
IDC
See: Insertion Data Signal
Horizontal Sync
Identification Signal [SECAM]
See: Line Sync [Pulses]
See: Colour Identification Signal
Horizontal Timing
IDS
Relative timing of two sets of horizontal sync
pulses held in synchronism. An error in H-timing
results in horizontal shifts of TV picture
See: Insertion Data Signal
Synonyms: H-Timing
International Electrotechnical Commission. An
international standardisation organisation that
issues documents defining the technical
specifications for a very large range of
hardware, e.g. mains plugs and connectors, or
VCR tape formats
Hue
A term used as equivalent to the chrominance
signal phase. As such can be expressed in
degrees - e.g. ’’hue is 270 degrees’’. More
commonly used as a label for a chrominance
phase control
Hyperbolic Zone Plate
A Zone Plate test pattern consisting of family of
hyperbolic curves and showing a twodimensional spatial frequency domain in
Cartesian co-ordinates. Along the horizontal
axis of the pattern the vertical frequency rises,
and correspondingly along vertical axis the
horizontal frequency rises. This is in contrast to
the Circular Zone Plate where the vertical
frequency rises along the vertical axis of the
pattern, and correspondingly the horizontal
frequency rises along the horizontal axis
IEC
Image Contrast
Ratio of maximal brightness to the minimal
brightness of the TV picture
Synonyms: Maximal Contrast
Image Trail-Freeze
See: Action Track
Impulse Noise
Artifact of video signal transmission, e.g. via
satellite links. It may be suppressed by median
filtering. Sparklies is the term for the specific
form of impulse noise typical of marginal
satellite reception
Synonyms: Sparkles
33
Glossary
In-betweens
Interpolation
Jargon term to designate frames computed
by a computer animation workstation or DVE
to fill the time intervals between actual
defined or selected Keyframes. In the case of
a DVE, Trajectory settings are used to enable
the calculation of tweens
Synonyms: Zonal Mixing
Interpolation involves using existing sampled
data points to predict values between these
points. The simplest form of interpolation is to
connect these data points with straight lines (a
2-tap linear interpolation filter). Interpolation is
a branch of signal filtering theory and is
normally analysed as such. It is used in digital
video systems for picture size changes and
other manipulations including standards
conversion. The more taps that are used in an
interpolation filter, the better is the
interpolation quality - for instance a 4-field 4line Aperture standards converter gives better
spatio-temporal filtering results than a simple 2field 2-line machine.
Incidental Phase [Modulation]
Inverse Colour Bars
Synonyms: Tweens
In-Lay
Keying mode when a key signal of the mixer
(for instance a diamond shaped wipe pattern)
comes from a source other than the video
that will eventually fill the hole. The key source,
in this case, may be either internal or external
Change of the chrominance phase as a
function of chrominance level
Insertion Data Signal
Colour bars with inverted sequence of colours:
Black/Blue/Red/Magenta/Green/Cyan/Yellow/
White
Synonyms: Reversed Bars
Data line used by Eurovision network to
identify programme originators and sources
IRE
Synonyms: IDC; IDS
See: IRE unit
Interlace Ratio
IRE unit
Number of fields in a frame. E.g. in PAL and
NTSC systems the interlace ratio is 2:1
Acronym for the North American ’’Institute of
Radio Engineers’’. Also refers to the
measurement units introduced by this
organisation. As defined by ANSI/IEEE standard
205, ’’IRE units are a linear scale for measuring
the relative amplitudes of the components of
a television signal with a zero IRE reference at
the blanking level’’. In the NTSC system, the tip
of horizontal sync is located at - 40 IRE,
reference white level is at 100 IRE and a 1 Volt
peak to peak signal usually equals 140 IRE
units, so 1 IRE = 7.14285 mV
Interlaced Scanning
Scanning by splitting the TV frame into 2 or
more fields with the resulting frame raster
formed by interleaving the lines of the split
fields. Originally devised to reduce transmitted
TV picture bandwidth
Interline Twitter
See: Field Alias
Interline Flicker
See: Field Alias
34
Synonyms: IRE
Glossary
ISO
Jitter
International Organisation on Standardisation.
A powerful body involved mainly in hardware
standardisation. Through its branches, like the
International Electrotechnical Commission
(i.e.C),
the
International
Illumination
Commission (CIE), etc. , this organisation issues
Publications, containing, for instance, detailed
descriptions of magnetic tape recording
processes, the colorimetric co-ordinates of
CRT phosphors, and so on.
1. Timing instability of any signal with respect to
a given reference
2. Unwanted small periodic or random
displacement of some pixels, group of pixels,
or the whole TV image
JPEG
ITS
Compression
standard
for
digital
representation of still pictures, commonly used
in the computer industry. JPEG is an acronym
for Joint Photographic Experts Group [created
by ISO].
See: Vertical Interval Test Signals
Judder
ITS-1, ITS-2
See: Jerkiness
Vertical Interval Test Signals used in the UK.
Usually inserted in lines 19 (ITS-1) and line
20 (ITS-2)
ITU
International Telecommunication Union. A
body of the United Nations Organisation. It has
many branches, one of them is ITU Radio
Communication Sector - ITU-R formed in 1993,
replacing the CCIR, also was known as ITU-RB
(Radio Branch of the ITU)
ITU-RB 601
See: Rec 601
ITU-RB 656
See: Rec 656
Jaggies
Professional jargon for spatial aliasing on nearhorizontal lines in a TV picture. Caused by lack
of pre-filtering
Synonyms: Stair-stepping
Jerkiness
Term to describe temporal aliasing. An artifact
due to deficiency of temporal filtering, e.g. in
the process of linear standards conversion (as
opposed to motion compensated standards
conversion). It is for this reason that 4-field
converters have less judder than 2-field
converters the temporal filtering is better
Synonyms: Judder
K-Factor
A generalised measure of linear distortions in a
signal path which conforms to the subjective
visibility of overshoots and echoes. Usually
evaluated with the help of a tolerance
graticule on a waveform monitor displaying a
2T-pulse. Sometimes factorised down to such
expressions as ’’K-rating on pulse to bar ratio’’
which implies only pulse height measurements
(ignoring overshoots), or ’’K pulse’’ which
implies
only
overshoot
and
width
measurements (ignoring pulse height)
Synonyms: K-Rating
K-Rating
See: K-Factor
Kaleidoscope
A digital video effect in the category of
multiple Mirror effects emulating the classic toy
of the same name
Key
The general term for the process of
superimposing video from one source (the
foreground) on top of another source (the
background) using a cut-out or ’’key’’ signal to
control which of the two signals is visible at any
one point. The key signal may be derived by
many different means.
Synonyms: Keying
35
Glossary
Key [signal]
Key Mask
Video control signal used in mixers and DVE
devices to cut a ’’hole’’ in the background
video into which fill video (the foreground) will
be placed by a Keyer. Key signals can come
from a variety of sources
A Key modifier that allows an operator to keep
portions of the foreground video from actually
being keyed at the mixer output. For example,
if many lines of text are showing at the output
of a character generator, but only a single line
is desired, a key mask could be placed over
all others. When a key is performed with this
video, only the desired line will actually be
keyed, leaving no evidence that any others
existed. Note that the key mask itself will not
be visible at the switcher output. Key masks cn
also be inverted, whereby only the video
outside of the mask will be keyed and all other
video on that key bus will not be keyed. There
are different ways to control the shape of a
key mask, such as Box Mask controls, through
the mixer’’s wipe generator or through a mixer’s
External Key input
Synonyms: Key video; Silhouette [signal]
Key Bus
A vision mixer bus used to select the input to a
mixer keying circuits
Key Clip
See: Key Level Set
Key Fill
See: Foreground [Video]
Key Gain
The key gain control of a mixer adjusts the
sensitivity of the keying circuits. It is adjusted to
provide the desired edge sharpness and
foreground object transparency. If the gain is
set high then the result is called Hard Key
A mixer function that causes only an outline (or
derived edges) of the key signal to be used
instead of the actual key signal
Key Level Set
Key Tracking
A control used to set the threshold for the
luma-key circuits. A hole will be cut in the
background video in any place where the
foreground luminance level is greater than the
clip level setting. Fill video will then be placed
in these holes
A Geometry Effect where the size and position
of the modified image tracks the boundaries
of a Key signal, e.g. where a piece of blue
cardboard held by an actor appears as an
Inlay of a different live scene. The main feature
of this effect is that the geometry of the
modified inlay image follows all variations of
the key signal
Synonyms: Key Clip
Key Outline
Key video
See: Key [signal]
Keyframe
Keyframes are used in vision mixers and DVEs
to create a sequence of independent events.
Keyframes specify important points in an
effect trajectory or the rate of change of
effect parameters. Keyframes also exactly
specify the changeover point between
effects. A series of keyframes can be built-up
with linear and non-linear Transitions to create
a complex event which may then be
executed with a single command
Keying
See: Key
36
Glossary
Lag
LCD
Artifact due to excessive temporal filtering,
e.g. in the process of standards conversion. It is
visible as a trail following a moving object in
the TV picture. The standards converter lag
appears as discrete variations in trail
amplitude whereas the lag generated by a
CRT or tube camera decays smoothly
Note: strictly speaking lag is the cause of the
problem and Smear is the resultant artifact
Liquid Crystal Display. A display device
invented in the 1970s. LCDs work by changing
the polarization of light by means of applying
an electric field across a thin layer of special
transparent liquid. The polarized light is then
viewed through a suitable filter which
generally is dark when the polarization does
not match and transmissive, or “light” when it
does. LCDs are characterised by ultra-low
power consumption and compactness. This
must be balanced against indifferent contrast
ratio and poor viewing angle. LCDs are not a
source of light and must therefore be
externally lit. At present, large LCD displays are
extremely expensive, although this situation is
likely to change rapidly
Synonyms: Smear
Large Area Flicker
Artifact of television raster display due to low
Frame Rate. Sometimes called ’’broad area
flicker’’. Visibility of this artifact increases with
brightness and is especially conspicuous in
peripheral vision. This artifact decreases
dramatically as the frame rate increases from
50 Hz. It can be improved by Display UpConversion
LD
See: Horizontal Drive
Legal Colour
A colour with R, G, B values each of which
must lay within the range from Reference
Black to Reference White. Non-legal values
may commonly be seen for example, after
the processing of 4:2:2 signals. The concept of
legality of colour is directly linked with the
chromaticity co-ordinates of the TV System
primary colours, hence standards converting
(e.g. from NTSC to PAL) has the potential to
produce illegal colours unless special colour
legalisers are incorporated
37
Glossary
Letterbox
Line Doubling
Viewed picture format with full horizontal
screen occupation and reduced vertical
screen occupation, i.e. with black bands
above and/or below the active image area
Simplified variant of line rate up conversion
where every other line of the output signal is
merely a copy of the previous one, usually for
display purposes to reduce the Visibility of Line
Structure and the Interline Flicker
Lightning [Display]
Proprietary Tektronix display mode showing
two separate projections (Y, Pb and Y, Pr) of
three-dimensional
Y,
Pb,
Pr
space.
Complementary
to a vectorscope but showing luminance chrominance relationships, the lightning mode
is convenient for checking gain and delay
errors in an analog component video path
Line
1. The track of single horizontal movement of
TV Aperture; e.g. the course of the scanning
beam of a CRT display during one line, the
spot size representing the aperture size
2. Time interval while single horizontal
movement of TV Aperture takes place (line
period)
3. Commonly used measure of spatial
frequency of periodic pattern in TV picture
expressed as a ratio of picture height to the
half period of the pattern; e.g. for 625/50/2:1
scanning standard the 1 MHz video signal
produce on TV screen a periodic pattern with
spatial frequency about 78 tvl
Line Array Telecine
See: CCD Telecine
Line Blank
See: Horizontal [Blanking] Interval
Line Blanking
Line Drive
See: Horizontal Drive
Line Frequency
Number of [TV] lines transmitted per second
Synonyms: Fh; Line Rate
Line Numbering [System]
The method of counting the TV lines in a frame
or in a colour frame, that usually must be
approved by some regulatory body. This issue
is important to avoid confusion, but does not
directly influence the TV picture properties.
In the 625/50/2:1 standard, line 1 is defined as
the line starting coincident with the start of the
first broad pulse in the vertical sync group. On
the display screen this puts the raster of field 1
above the raster of field 2.
In 525/59.94/2:1 standard line 1 is defined as
the ine starting coincident with the start of the
first equalising pulse in the vertical sync group.
In this case, on the display screen the raster of
field 2 raster is above the raster of field 1. Note
that the international notation ’’Frame line 263’’
may be referred to in American practice as
’’line 1 of field 2’’.
Line Rate
See: Line Frequency
Line Rate Conversion
See: Horizontal Blanking
Conversion of video signals from one Line Rate
to another, usually preserving Frame Rate
Line Comb [Filter]
Line Sag
Comb Filter using inputs from at least two
spatially adjacent lines in the same field
See: Line Tilt
Line Datum
A reference time moment at the mid-level
crossing point of the leading edge of the line
sync pulse. This is the default timing reference
in the TV environment (as opposed to the
Active Line start which is commonly used in
computing environments)
Synonyms: 0h; Line Start [Moment];
Time Datum
38
Line Scanning
See: Horizontal Scanning
Line Start [Moment]
See: Line Datum
Glossary
Line Sweep
Luma
Sweep signal modulated along the TV line
assuming that the next line will contain the
same signal, so all the lines in the field form a
vertical pattern, e.g. with uniform frequency
sweep from left to right
See: Luminance [Signal]
Line Sync [Pulses]
Sync pulses with the period of horizontal
scanning transmitted within a synchronisation
signal or separately
Synonyms: H-Sync; Horizontal Sync
Line Synchroniser
A device performing variable delay function
from minimal up to several TV lines, for the
purpose
of Synchronisation. Slight short-term differences
(i.e. jitter) between the Line Rates of incoming
and
reference
signals
can
be
accommodated but the long term rates must
be equal. Note that the phases of these two
signals could be different
Line Tilt
Tilt measured across the top of the bar in a Bar
test signal. Measurement is along the
horizontal axis using a waveform monitor. Line
Tilt is a result of medium frequency distortions
Luma-Key
A simplest way to derive hole-cutting
information from a key signal by comparing its
video level with some manually-set threshold.
This is in contrast to a Chroma-key, where the
hole-cutting signal is derived from chroma
information. Luma-key is seldom used to
extract key signals from live TV pictures
because of poor selectivity and relatively high
gain, thus it is usually used for down-stream
keying of captions
Lume
See: Luminance [Signal]
Luminance [Signal]
Signal carrying the information about the
brightness of TV picture. Usually produced by
combination of the primary colour signals R, G
and B, e.g. for NTSC, PAL and SECAM systems:
Y = 0. 299 R + 0. 587 G +0. 114 B
Synonyms: Luma; Lume; Y.
M/E
See: Mix Effects [Amplifier]
Synonyms: Line Sag; Line Time Distortion
Master Control Room
Line Time Distortion
See: Central Control Room
See: Line Tilt
Matrix Switcher
See: Test Matrix
Device for the routing and distribution of
several video (and possibly audio) signals to
several destinations
Line-Locked Subcarrier
Synonyms: Routing Switcher; Switching
Line-based Test Pattern
A colour subcarrier with constant Colour
Subcarrier Offset
Linear Chroma-Key
Improved variant of Chroma-Key with MultiLevel Key signal. It combines the advantages
of both smooth cut hole edges (typical for
linear key extraction) and good ability to
discriminate between objects, inherent to
chroma-key processing
Matrix
Matrixing
Weighted summation of several signals, e.g.
the transformation of R, G, B signals into Y, R-Y,
B-Y, or vice versa, the transformation of Y, R-Y,
B-Y signals into R, G, B
Matte
See: Multi-Level Key
Synonyms: Chroma Matte; Multi-Level Matte Fill Key
Chroma Key
A key where the hole is filled with the output of
Linear Key
See: Multi-Level Key
a Matte Generator
Synonyms: Matte Key
39
Glossary
Matte Generator
Modulated Pedestal
See: Background Generator
A Test Signal Pedestal swinging within a valid
range of levels, e.g. from 10 % to 90 % and
back in a period of 10 seconds. The purpose of
modulating the Test Signal Pedestal is to check
some
level-dependent
parameter,
for
instance frequency response (note that in this
case a sweep will be superimposed over the
modulated pedestal)
Matte Key
See: Matte Fill Key
Maximal Contrast
See: Image Contrast
MCR
See: Central Control Room
ME
See: Mix Effects [Amplifier]
MII
Matsushita’s tradename for component
analog tape recording format. The equipment
has specific Pr and Pb levels in 525/59.94
mode
MII [Colour] Bars
1. In 625 version: the same as EBU Bars in YPrPb
format, white level is 700 mV
2. In 525 version: 100/7.5/75/7.5 colour bars in
YPrPb format with white level at 700 mV (i.e.
the same as 625 version, not the usual 100 IRE)
Mirror
A digital effect where the left and right or top
and bottom sides of the displayed picture are
swapped
Mix
See: Cross-Fade
Mix Effects [Amplifier]
The part of a vision mixer or digital video
effects device where video signals from
several sources are combined to create Mixes,
Fades, Keys, etc.
Synonyms: Combiner [of DVE]; M/E; ME
Mixed Blanking
See: Composite Blanking
Mixed] [Composite] Sync
See: Synchronisation Signal
Mixer Bus
See: Bus
Modulated Bar
See: Chroma Bar
40
Modulated Pulse
See: Composite Pulse
Modulated Ramp
See:
Sawtooth
with
[Superimposed]
Subcarrier
Modulated Staircase
See:
Staircase
with
[Superimposed]
Subcarrier
Modulated Wipe
In the context of vision mixer wipes,
modulation is the process whereby the edges
of a wipe pattern can be made to ’’wobble’’
at a rate, waveform and amplitude set by a
user-adjustable oscillator
Moiré
Artifact of TV picture in the form of a wavy
unwanted pattern, a simple example of which
is observed by holding one comb behind
another. It is usually caused by interference or
lack of sampling rate. E.g. the Cross-Colour
moiré pattern is coloured even if the source
picture is not - this may be caused by the
beating of the luminance frequencies
generated by, say, a tweed jacket, and the
colour subcarrier frequency
Monochrome
Literally means single colour. Often used to
indicate achromatic, colourless as opposed to
coloured. This term is more strict and formal
than "Black-and-White".
A monochrome picture could be produced
from a colour source. by setting the colour
difference signals to zero, leaving only
luminance component.
Glossary
Morphing [Effects]
Motion Compensation
Any digital video effect that transforms an
object’s shape and colours into those of
another object.
This expression is commonly used in the
computer graphic domain to describe an
effect whereby object(s) in one picture are
made to apparently transform into object(s)
on a subsequent picture with the transition
being as seamless and convincing as possible.
Many different approaches exist to control this
process but the most common is to set up a
grid of key points on a start frame and a grid
of key points on the end frame. Given start
points always move to a particular point on
the destination grid via an adjustable
trajectory. This gives the required control over
the change in shape. A controlled cross-fade
is then set to that the actual pictre content
(i.e. luminance and colour difference vlaues)
also blends between the start and end points
thus completing the illusion. An example of this
might be a person’s face changing into the
front of a car
Scheme of video signal processing (e.g.
standards conversion), involving the use of
Motion Vectors to skew the filtering axis (for
example
the
interpolation
axis)
by
correspondingly shifting parts of the source TV
fields
Synonyms: Morphs
Morphs
See: Morphing [Effects]
Mosaic
See: Pixellation
Motion Detection
Operation of video signal processing aimed to
produce an output indicating the pixels or
groups of pixels which belong to moving
objects as opposed to static portions of the
picture
Synonyms: Motion Recognition
Motion Estimation
Operation of video signal processing designed
to produce a Motion Vector signal
Motion Portrayal
Ability of TV system or device to reproduce the
moving objects in a TV picture without visible
artifacts
Motion Recognition
See: Motion Detection
Motion Resolution
See: Dynamic Resolution
Motion Vector
A design that senses motion in order to alter
the way it functions, for the purpose of
avoiding or reducing some motion related
artifacts
A two-component video signal showing the
magnitude and direction of moving object
displacement over given time interval, e.g.
during one TV field. Usually represented in
Cartesian co-ordinates, but could equally well
be represented in polar notation
Motion Blur
Moving Dots
1. Generally, Motion Blur is an effect caused
by integration. Put more simply, it is normally
caused by the image being composed from a
sum of the latest image plus a smaller portion
of the previous sum and so on. The result of this
is that moving objects leave a trail behind
them giving rise to a blurred appearance.
Such an artifact is normally associated with 2field standards conversion or tube cameras.
2. As a digital video effect the above artifact
may be generated deliberately
See: Cross-Luminance
Motion Adaptive
41
Glossary
MPEG
Multi-Level Key
Digital compressed video signal format used
for distribution and contribution purposes
according to ISO/IEC MPEG1 or MPEG2
specifications [MPEG is an acronym for
Moving Pictures Experts Group]. The number of
different varieties of MPEG is much more that
two. For instance, MPEG2/50 is not compatible
with MPEG2/59.94.
The original MPEG1 is a field-based system
which was designed to enable ’’full-motion
video’’ to be compressed to around 1.2 Mbit/s
and thus be playable from a CD-ROM. MPEG2
has been conceived to overcome the
limitations of MPEG1. The algorithms are
scaleable into many ’’profiles’’ and ’’levels’’ to
suit almost any usage from VOD (Video on
Demand) to studio and HDTV. The encoding is
complex, especially in view of the fact that
consumer decoders have to be capable of
accepting all main profiles and levels whilst
remaining as simple as possible
A key signal extraction where the resulting key
signal levels are derived with moderate gain
taking into account the nuances of source
pictures such as shadows or soft edges (as
opposed to Hard Key). It produces a smoother
and more natural looking transition between
the foreground and background objects than
would otherwise be possible.
Note that the term ’’Matte’’ originated from
cinematography where, traditionally, a matte
is a hand-painted glass plate with areas
obscured to prevent exposure of the emulsion
or alternatively with a false scene painted and
positioned within the depth of field of the
camera so that in the resultant shot the actual
scene and the painted scene are seamlessly
combined to appear as real.
Sometimes the term ’’Matte’’ may mean
colour background
Multi-grab
See: Skip-Field
Multi-Image
Digital video effect where the displayed
picture contains several different input images
reduced in size and positioned side by side
Multi-Image-Freeze
A Multi-Tile effect with the addition of freeze,
so that different temporal phases of a single
live video source are frozen and positioned (or
’’dropped’’) in different areas of the screen
Multi-level Chroma Bar
Test signal in a form of colour subcarrier
modulated by staircase signal i.e. , the
chroma amplitude rises in discrete steps along
the TV line. This signal is usually on a grey level
pedestal
Synonyms: Chrominance Staircase
Multi-Level Chroma Key
See: Linear Chroma-Key
42
Synonyms: Linear Key; Matte
Multi-standard
A generic term describing equipment that will
operate correctly with a variety of signals
belonging to different Colour TV Systems
Multi-Tile
Digital video effect where the displayed
picture contains several copies of the same
live or frozen image reduced in size and
positioned side by side
Glossary
MultiBurst
Noise Reducer
Test signal in a form of series of sinusoidal bursts
of different frequencies on a Pedestal. It has
the same purpose as a Line Sweep
A device for improving signal to noise ratio
by sophisticated filtering. Such devices can
usually perform some other functions, e.g.
synchronisation or transcoding
Multimedia
A term coined in the 1980s to describe a
computer capable of outputting sound as well
as vision, hence “multi-media”. Such
machines would seem archaic now, and the
term has grown to mean the convolution of
high quality sound, reasonable motion pictures
and a variety of human interface devices in a
powerful computing platform. To all intents
and purposes the term Multimedia is merely a
marketing buzzword
Nominal Viewing Distance
MultiPulse
A type of mix where the output at any point in
the picture consists exclusively of whichever
input signal had the greater amplitude. This is
in contrast to a normal Mix which produces a
linear sum of the inputs
A test signal in a form of series of sine-squared
pulses and Composite Pulses of different width
and with different filling frequencies. This test
signal has the same purpose as a Line Sweep,
but will also check phase response and group
delay distortions
NAB
National Association of Broadcasters. An
American
association
which
assists
broadcasters in several ways including
publishing
technical
information
and
sponsoring a number of trade shows and a
large exhibition every year.
NAM
See: Non-Additive Mix
Negative
A digital video effect that inverts the image
RGB levels (effectively by subtracting them
from Reference White level) so that it appears
as photographic film negative. This effect may
could be combined with complete desaturation of the image to create a realistic
monochrome negative appearance
Noise
1. Any unwanted signal, usually not linked with
TV picture content, for instance, interference
from adjacent channel
2. In general: a random signal as opposed to a
regular signal, e.g. mains hum usually is not
normally considered to be ’’noise’’
Noise Coring Test [signal]
Distance between viewer and TV picture at
which the TV raster line structure becomes
invisible. E.g. for 625 line system the
recommended viewing distance is from 5 to 7
times screen height
Nominal White Level
See: Reference White Level
Non-Additive Mix
Synonyms: NAM
Non-Interlaced Scanning
See: Progressive Scanning
NRZ
Non Return to Zero. A coding scheme that is
polarity sensitive, usually a low signal level
means logical ’’0’’ and high level means logical
’’1’’. This coding scheme suffers the
disadvantage that it contains frequency
components from DC and is thus unsuitable for
many applications. An example of NRZ is a
simple RS232 serial data link
NRZI
Non Return to Zero Inverse. A scrambling
scheme that is polarity insensitive, usually low
signal level means no change in logical values
and high level means transition from one
logical value to another, e.g. from ’’0’’ to ’’1’’ or
from ’’1’’ to ’’0’’. This coding scheme has the
advantage that it contains no DC component
which makes it more suitable for the majority
of applications
NTC Combination
See: NTC-7 Combination
NTC Composite
See: NTC-7 Composite
See: Coring Test [signal]
43
Glossary
NTC-7 Combination
Odd Field
Vertical Interval Test Signal specified by NTC
(a US body) for the NTSC system. It combines
the features of VITS test lines CCIR-18 and
CCIR-331
Field with odd number in the interlaced field
sequence
Synonyms: NTC Combination
NTC-7 Composite
Vertical Interval Test Signal specified by NTC (a
US body) for the NTSC system. Similar to VITS
test line CCIR-330
Synonyms: NTC Composite
NTSC
1. TV system in which the chrominance signal is
produced
by
Quadrature
Balanced
Modulation of colour
subcarrier.
The
modulating signals are the colour difference
signals I and Q. Note that the I and Q axes are
rotated by 33 degrees with reference to the
colour burst subcarrier
2. Acronym for National Television System
Committee (USA), which first devised the
system in 1953
NTSC 4.43
Non-broadcast colour TV system primarily used
when certain modified PAL equipment is used
for playing back consumer NTSC tapes with
the colour-under subcarrier heterodyning to
4.43 MHz instead of 3.58 MHz
Nyquist Frequency
Terms used in connection with sampling.
Named after Harry Nyquist (Don’t forget
however the names of Whittaker, Kotelnikov
and many others). The Nyquist rate is
considered the minimum sampling frequency
for correct digital reproduction of a given
signal
(twice
the
signal
bandwidth).
Alternatively the Nyquist frequency is the
highest signal frequency which can be
correctly reproduced for a given sampling
rate (half of the rate). Engineering reasons
may, however, dictate the use of higher
sampling rates that that given by the Nyquist
rule
Synonyms: Nyquist Limit; Nyquist Rate
Nyquist Limit
See: Nyquist Frequency
Nyquist Rate
See: Nyquist Frequency
44
OIRT
French acronym for International Radio and
Television Organisation. This was the eastern
Europe regional broadcasters’ union. In 1993
merged with EBU.
On-Air
See: On-Line
On-Lay
Keying mode when the mixer creates a key
signal from the video that will itself eventually
fill the hole. A common example is simple
insertion of captions (generated with a black
background) over the desired programme
output. In this case the any luminance value
above black can be easily detected to make
a key signal for the captions
Synonyms: Self Key
On-Line
An indication that a particular device is ’’on
line’’. This indication, usually a lamp or LED, can
be on the switcher itself, or on a remote piece
of equipment, such as a monitor or a camera.
A source’s tally is activated automatically
when the source is selected via the mixer’’s
program bus
Synonyms: On-Air
Glossary
Orthogonal Sampling
Page Burn
Sampling with orthogonal structure, i.e. in such
a way that corresponding samples in each TV
line align vertically
A proprietary Snell & Wilcox digital video
effect combining a pseudo-random wipe
shape with a pseudo-random colour edge
Oversampling
Page Split
Sampling with a rate much higher that Nyquist
rate, e.g. to reduce the cost and improve the
performance of the pre-filter. Also applicable
to post-filtering where the data are
upsampled for use in oversampling output
stages
A digital video effect where the displayed
picture appears as though it is put on the
surface of a page which is then split into
several rectangular sections and made to fly
apart
Overscan
A two or three-dimensional digital video effect
where the displayed picture appears to be
put on the surface of a page, the corner of
which is slowly pulled up and back to reveal
the other side. If the other side contains a
different live picture it is known as a Double
Sided Page Turn
Displaying less than the complete area of a TV
image to a viewer (i.e. , scanning inside the
Active Image area). All TV
sets are
overscanned by a few percent. Some
professional devices, such as standards
converters, perform the overscan and crop
(re-blanking) operations to avoid the visibility
of unstable blanking edges, head switch
effects etc.
Synonyms: Overscanning
Overscanning
See: Overscan
Overshoot
Artifact caused by imperfection of system
frequency response. Looks like excursions
beyond the steady state either before (preshoot) or after (after-shoot, post-shoot) of the
signal edge. Usually expressed as a
percentage of step signal amplitude above
the steady state level. Note that in the process
of aperture correction pre- and post-shoots
may be deliberately added to improve the
apparent picture sharpness.
Packet
See: Data Packet
Page Turn
PAL
Colour TV system in which the chrominance
signal is produced by Quadrature Balanced
Modulation of colour subcarrier. Modulating
signals are the colour difference signals U and
V. In a PAL chrominance signal a PAL Switch
inverts the phase of the modulated V
component every TV line. PAL (Phase
Alternated Lines) system was proposed by Dr.
Walter Bruch (Germany). There are several
Broadcast Standards using this Colour TV
System:
625/50 PAL-B, D, G, I, K with 4.433 MHz
subcarrier (commonly known simply as ’’PAL’’),
525/59.94 PAL-M with 3.576 MHz subcarrier,
525/59.94 PAL-N with 4.433 MHz subcarrier
PAL Switch
See: 2H
PAL Switching Signal
See: 2H
45
Glossary
PALplus
Patch Panel
Enhanced widescreen letterboxed TV system
compatible with conventional PAL system
using the ’’Motion Adaptive Colour Plus’’
technology to reduce cross-effects plus a
special Helper Signal to recover full vertical
luminance resolution
Device for manual switching and routing of
signals. Connectors are provided for sources
and destinations. The user makes the desired
configuration with physical jumper links
Pan and Scan
Aspect ratio down conversion with full vertical
screen occupation and on-line control of
horizontal centring
Synonyms: PanScan
Panic Freeze
A momentary repeat of one TV frame or field
from the live video sequence, usually caused
by temporary loss of synchronisation
PanScan
See: Pan and Scan
Parade [Display]
A convenient mode for displaying component
video signals on a waveform monitor. The
three signals (R, G, B or Y, Pr, Pb) are shown
multiplexed with the horizontal deflection rate
being one third of line rate (or field rate). The
disadvantage of parade mode is that each of
R, G, B (Y, Pr, Pb) are from successive lines and
thus only one line in three is shown for any
single component
Parallel Analog Interface Format
See: Analog Component Format
Parallel Digital [Video] Interface Format
Format in which the digital video signal is
transmitted byte-wise via a number of parallel
wires, where each pair of wires carries a single
bit. Typically, 8 or 10-bit video data are
transmitted via 25-pin D-type connector with
clock rate 4 x 3.579 MHz (digital composite
NTSC and PAL-M), 4 x 4.433 MHz (digital
composite PAL), or 27 MHz (digital component
4:2:2)
Synonyms: Bit Parallel Format; PDI
Parallel-To-Serial Converter
Device for the conversion of digital video data
from parallel interface format to serial
interface format
Synonyms: Serialiser
46
Patterned Matte
Variant of Background filled with some
repetitive texture or pattern, e.g. a ’’brick wall
matte’’
PDI
See: Parallel Digital [Video] Interface
Format
Pe
See: Picture Element
Peak Black [Level]
See: Black Peak [Level]
Peak White [Level]
Level of video signal corresponding to the
area of the TV picture with maximal brightness.
The actual value is not specified by a standard
but depends on the picture content,
hardware settings, etc.
Pedestal
Difference between reference black level
and blanking level in the luminance signal.
Relevant only for NTSC (USA) and PAL-M
systems, in all other systems there is no
difference, so reference black is set at
blanking level.
Note that NTSC as used in Japan has zero
setup level
Synonyms: Set-Up
Pel
See: Picture Element
Perspective
A digital effect that cause rectangles in a
displayed picture to appear as trapezoids,
adding virtual depth to the picture
PGM
See: Programme [Bus]
Glossary
Phase Correlation
Pixellation
Method of Motion Estimation based on the
measured position of the peaks on a phase
correlation surface derived using Fast Fourier
Transform (FFT), spectrum normalisation and
Inverse Fast Fourier Transform (IFFT).
A digital video effect where the displayed
video appears as though it is were composed
of many small square or rectangular tiles, as
though there were far fewer pixels in the
complete image. Normally implemented by
assigning the same level to several adjacent
pixels. Note that the term Tiles is sometime
used (at least in this document) to describe
the Multi-Tile or Multi-Image effects
Phase Inversion
See:
SECAM
Chrominance
Phase
Switching
Synonyms: Mosaic; Tiles
Philips Mire
Planes
See: Radial Mire
See: Cross Planes
PI Sequence
See:
SECAM
Chrominance
Phase PLUGE
Switching
Pick-Up
See: TV Analysis
Picture Aspect Ratio
Aspect ratio of the TV picture, possibly
different from the display screen aspect ratio
Picture Element
The smallest area of TV picture defined by TV
standard; usually refers to discrete value on a
sampling grid; a colour pixel is a trio of values
representing either red, green and blue
intensity, or luminance and two colourdifference intensity values.
Synonyms: Pe; Pel; Pixel; Pxl
Pitch
A term borrowed from aeronautics to describe
the effective static rotation of the aircraft
about
an
imaginary
horizontal
pin
perpendicular to the direction of motion. Thus
the aircraft can be moving forward but not
necessarily pointing forward but be nose up or
nose down by the amount of the pitch angle.
In digital video effects this term can be used to
describe the positioning of the effect (rotation
about the X axis)
Acronym for Picture Line-Up Generating
Equipment. PLUGE is a Test Pattern for
adjustment of the brightness and contrast
controls of display devices. A PLUGE test
pattern contains boxes with levels slightly
higher and slightly lower that black level.
Some variants also include boxes with levels
close to Reference White level and/or Grey
Scale test .
When the settings are correct only one of
each pair of boxes can be visually
distinguished
Posterisation
A digital video effect that reduces the number
of colours used to represent the image on
screen, the simplest way being to reduce the
number of bits used to represent the
chrominance and luminance data (for
instance from eight to four). When used to
extreme gives a ’’poster-like’’ appearance
Pr, Pb
Pixel
Colour difference signals scaled to fit the
parallel analog component interface format:
Pr = 0.71327 (B-Y)
Pb = 0.56433 (B-Y)
These are the equations designed to provide
700 mV p-p Pr and Pb levels for 100 %
saturated sources. Other scalings exist but the
above is the only standard value
See: Picture Element
Pre-set [Bus]
See: Preselect
47
Glossary
Preselect
Program Stream [MPEG]
In a Vision Mixer the pre-set bus is where the
next video to be put on-line is selected. The
preselect bus outputs the video signal that will
be present at the main programme output
after the next T-Bar transition or autotake.
Upon completion of the transition the
preselect bus will normally output the signal
that was the previous programme output
A bitstream packaging Elementary Streams
together when they belong to one
programme, with one clock. Program streams
have variable-length packets and are
intended for recording or for transmission over
clear channels with few errors.
Synonyms: Pre-set [Bus]; PST
Preview [Bus]
This bus gives the Vision Mixer operator the
opportunity to see sources and/or combined
pictures before they are included in the
outgoing (programme) signal
Synonyms: PVW
Primary Colour Signals
Signals carrying information about intensity of
Red (R), Green (G) and Blue (B) components
of TV picture
Synonyms: Primary Signals; RGB
Primary Colours
Red (R), Green (G) and Blue (B) colours with
colorimetric parameters according to a
specified TV Standard
Primary Signals
See: Primary Colour Signals
Proc Amp
See: Processing Amplifier
Processing Amplifier
Programme [Bus]
The Mixer Bus selecting the signals to be fed
directly to the main (programme) output.
Programme is also spelled ’’Program’’
Synonyms: PGM
Progressive Scanning
Scanning with Interlace Ratio equal to unity.
This accurate, but rather meaningless
definition means in essence that all the lines
comprising a picture are scanned in each
field and hence a field is equal to a frame.
Synonyms:
Non-Interlaced
Scanning;
Sequential Scanning
Protocol
A generic term for any set of rules and
conventions used for the transfer of
information. The protocol definition may
include hardware specifications where
appropriate. For example, a serial interface
protocol for an editor defines exactly what
digital information is required for the editor to
be able to control a switcher, plus the physical
interface parameters
Pseudo Colours
A device which makes it possible to modify or
adjust many different parameters of a video
signal, such as chroma level, burst level, black
level, burst phase, etc.
A digital video effect where the output colour
palette is created from the luminance
component of an input image, so for example
dark grey might become blue, grey become
red, light grey become orange, etc.
Synonyms: Proc Amp; Video Processor
PST
Production Standard
See: Preselect
Scanning
Standard
or
TV
System
predominantly used for the production of TV
programmes in a given area, e.g. ’’1125 HDTV
production standard’’ or ’’composite PAL
production standard’’
Production Switcher
See: Video Mixer
48
Glossary
Pscho Optics
Quadrature Modulation
The science of how the eye and brain respond
to visual stimuli. Motion pictures only work at all
because the brain is fooled into thinking a
series of still images is actually a moving
picture. This is a Psycho-Optical effect. Sound
technology has a parallel in the science of
Psycho-Acoustics
Balanced
amplitude
modulation
and
summation of in-phase, i.e. sin(f t), and
quadrature,
i.e. cos(f t), continuous waves of the same
frequency by two different signals
Pull-in Range
See: Capture Range
Pulse and Bar
Popular test signal consisting of a 2T-pulse and
a T or 2T white bar
Pulse-To-Bar Ratio
Measure of linear distortions in a signal path.
Usually expressing the level of the 2T-pulse
peak as a percentage of Bar level, e.g. 100 %
+/- 0. 25 %
Push Off
A digital effect where a frame of video
appears to slide out of view, revealing a
second frame of video, with the revealed
video remaining stationary.
See: Push-On, Push-On/Push-Off
Push On
A digital effect where a frame of video
appears to slide into view on top of the
previous video, with the previous video
remaining stationary. See: Push-Off, PushOn/Push-Off
Push-On/Push-Off
A digital effect which is both Push-On and a
Push-Off. One frame of video slides out of view
while another slides into view. This effect
usually requires two channels of digital effects
device: one for the Push-Off and one for the
Push-On, although Snell & Wilcox DVE products
need only a single channel
PVW
See: Preview [Bus]
Pxl
See: Picture Element
Quantization Errors
Digital systems are designed to represent
voltages only in predetermined values called
quantization levels. For example, if a particular
system is only capable of storing the numerical
equivalent of 1 millivolt steps, an actual value
of 8.4 millivolts would be stored as 8.0 millivolts.
The difference between original analog signal
and quantized signal is called quantization
noise because it looks almost random. In fact
this difference is not random but determined
by the analog signal, so the term ’’quantization
errors’’ is more accurate
Synonyms: Quantization Noise
Quantization Noise
See: Quantization Errors
Quantization Scale
A rule linking the digital code word values with
analog video signal levels; e.g. for 4:2:2 format
the digital luminance black level is 16 and the
digital reference white level is 235, so 700 mV
of analog signal are equivalent to 219 digital
levels (in normal 8-bit representation digital
levels range is from 0 to 255)
Radial Mire
Sweep test pattern in a form of a ring filled
with several (usually from eight to thirty) radial
lines. The spatial frequency is inversely
proportional
to the distance from the ring centre. This
pattern is useful to view the ratio between
horizontal
and vertical sharpness, e.g. the results of twodimensional enhancement
Synonyms: Philips Mire
Ramp
Test signal in the form of a linearly rising ramp,
to measure signal path non-linearity
Synonyms: Sawtooth
Rate Conversion
See: Sampling Rate Conversion
49
Glossary
Rec. 569
Reference Black
CCIR Recommendation giving the general
definitions for the components of Vertical
Interval Test Signals
See: Reference Black Level
Rec. 601
description of a set of digitisation and
interface formats, based on the idea of
common sampling rate for both 625/50 and
525/59.94 scanning standards. To describe the
family of sampling rates a special notation was
introduced,
where
the frequency of 3.375 MHz is used as unit of
measurement. So, the ubiquitous expression
’’4:2:2’’ means that the luminance signal Y is
sampled at 13.5 MHz and both Cr and Cb are
sampled at 6.75 MHz. Although it has not yet
been formally approved, the up-dated version
of ITU (CCIR) Rec. 601 will allow the users
the choice of operating at 360 Mbit/s (18 MHz
sampling rate) for widescreen or the original
270 Mbit/s (13.5 MHz sampling rate). Hence
the 10-years old Rec. 601, referring to 4:3
apect ratio operation, becomes Rec 601 Part
A,
and
the
new wide-screen modification will be known
as
Rec. 601 Part B
Synonyms: 601; ITU-RB 601; Rec. 601
Rec. 656
(CCIR) Recommendation 656 ’’Interfaces for
Digital Component Video Signals in 525-line
and 625 line Television Systems’’. A companion
document to Rec. 601 which specifies the
signal format to be used and the particular
characteristics of both serial and parallel
digital interfaces
Synonyms: CCIR-656; ITU-RB 656; Rec.
656
Recursive Effect
Any video effect applied recursively to the
combined or modified image using the multientry feature of a vision mixer, e.g. the ’’hall of
mirrors’’ effect, classically achieved by
pointing a TV camera at a monitor showing its
signal
Reduction
See: Zoom-Out
50
Reference Black Level
Level of video signal corresponding to the
black areas of TV picture (zero brightness
areas)
Synonyms: Reference Black
Reference Peak Composite [Level]
Maximal level of composite video signal
achievable with primary colour signals varying
from Black Level to Reference White Level. It
depends on the Colour TV System, e.g. in PAL it
is 133.4 %, attained at 100 % Yellow or 100 %
Cyan
Reference White [Colour]
White with predefined colorimetric coordinates which is assumed to be displayed
when primary colour signals are equal: R=G=B.
Reference whites vary between TV systems
which can cause problems in Standard
Conversion. E.g. the HDVS system reference
white differs from NTSC reference white, so a
Down-Converter should correct this difference
Reference White Level
Level of video signal corresponding to the
white areas of a TV picture with nominal
brightness. It depends on the Colour TV
System. This level usually serves as a 100 %
reference level to calibrate the gains and
settings of measurement devices
Synonyms: Nominal White Level; White
Level
Relief Mapping
A computer graphic term where an input
image is used to alter the shape of a surface
onto which it is mapped. For instance creating
the bumps on an orange by mapping an
image containing defocused white spots onto
a sphere. The whiter the image, the higher the
bumps
Synonyms: Bump Mapping
Rendering
The operation of computing a viewable
finished image which has been modelled in a
primitive form on a computer graphics
workstation or DVE.
Glossary
Resolution
Risers
1. An often misused term attempting to define
the ability of the hardware to reproduce fine
picture details. For instance, the expression
’’Resolution is 800 pixels’’ hints about hardware
capability to resolve 800 tvl (400 c/aph). In
fact, this is not correct because nothing is said
about the contrast of the high spatial
frequencies, so the actual resolution could be
much lower.
2. The Spatial Frequency at which the fine
texture contrast drops to the threshold of
visibility (e.g. 500 tvl at the noise leel). Usually it
is with reference to some specified texture
orientation, e.g. ’’vertical resolution is 288 tvl’’ or
’’diagonal resolution is measured at 45 degrees
orientation’’
3. Number of bits in quantized sample digital
representation; e.g. ’’10-bit resolution’’
See: Staircase
Reversed Bars
See: Inverse Colour Bars
RGB
Roll
A term borrowed from aeronautics to describe
the effective static rotation of the aircraft
about an imaginary horizontal pin in line with
to the direction of motion. Thus the aircraft
can be moving forward but not necessarily
pointing forward but be left or right wing up by
the amount of the roll angle. In digital video
effects this term can be used to describe the
positioning of the effect (rotation about the Z
axis)
Roll-Up
A two or three-dimensional digital video effect
similar to Page Turn. In this case the displayed
picture appears to be put on the surface of a
page, the corner of which is slowly pulled up
and then rolled in a cylinder (or cone)
revealing the other side
RollCall
See: Primary Colour Signals
Protocol used to provide decentralised control
system within the Snell & Wilcox product range
Ripple Effect
Rotation
A class of digital video effects involving where
the picture is modulated in the horizontal or
vertical axes in a variety of ways. A number of
different modulation waveforms are usually
available and can be separately applied
both vertically and horizontally.
The well-known Flag Wave effect can be
achieved by vertical ’’position modulation’’
together with horizontal ’’density modulation’’
plus optional lighting and shading modulated
by the same waveforms. The ’’density
modulation’’ variant is where source pixels are
made to occupy more or less space
depending on the modulating waveform
polarity.
Another popular effect is the Circular Pond
Ripple where a circular rings formed by
suitable sinusoidal modulation are use to
cause alternate clockwise and anticlokwise
displacement of source pixels based on the
highs and lows of the modulating waveform
Digital video effect where the image is rotated
about some predetermined axis. The axis itself
may rotate to create complex effects
Routing Switcher
See: Matrix Switcher
Rise Time
Length of time interval in which a given signal
rises from 10 % to 90 % of its total excursion
from one steady state to another
Synonyms: Build-Up Time; Edge Time
51
Glossary
RS-232C
Sampling Rate
An EIA serial digital interface standard
specifying the electrical and mechanical
characteristics of the communication path
between two devices using 25-pin D-type
connectors. This standard is used for relatively
short range control data communications and
does not specify balanced control lines. “See
also” RS-422
See: Sampling Frequency
RS-422
An EIA serial digital interface standard. This
standard
specifies
the
electrical
characteristics of balanced line digital
interface circuits. This standard is usable over
longer distances than RS-232C. Although
originally designed for use with 9-pin
D-type connectors, it is now often used with
others, including 25-pin D-types. “See also” RS232C
S-Video
See: Y/C Connection
S.
See: Synchronisation Signal
S/N
See: Signal To Noise Ratio
Sampling
Process of signal transfer from continuous time
domain to discrete time domain. Before an
analog signal can be processed in a digital
system, a digital representation of it must be
obtained. This is done by measuring the value
of the analog signal at regular intervals. The
values obtained are called samples. These
samples are then used to construct a digital
representation of the analog signal in the
quantization process.
Sampling Frequency
The value inverse to the sampling period
(sampling interval). For instance, according to
CCIR Recommendation 601 in 4:2:2 format the
analog luminance signal Y must be sampled
at 13.5 MHz and both Pr and Pb colour
difference signals at 6.75 MHz
Synonyms: Sampling Rate
Sampling Grid
See: Sampling Structure
52
Sampling Rate Conversion
1. The conversion of the Sampling rate of
digital signals by interpolation and filtering
2. As professional jargon, the expression '
'
rate
conversion'
'generally infers not only a change
of sampling rate but also colour encoding or
decoding, e.g. '
'
D1-D2 rate conversion'
'
Synonyms: Bit Rate Conversion; Rate
Conversion
Sampling Structure
Two or three-dimensional pattern formed by
the sampling points, e.g. in case of 4fsc
composite digital PAL signal the sampling
structure is skewed (not Orthogonal Sampling)
because of PAL subcarrier 25 Hz offset.
Synonyms: Sampling Grid
Satellite News Gathering
A version of Electronic News Gathering with
up-link transmissions of TV programmes usually
live via communication satellite
Synonyms: SNG
Saturation
See: Colour Saturation
SAV
Start of Active Video. A code word marking
the beginning of the Digital Active Line in
component digital systems
Sawtooth
See: Ramp
Sawtooth with [Superimposed]
Subcarrier
A variant of the Ramp test signal with
superimposed LF or subcarrier burst to
measure non-linearity, Differential Gain and
Differential Phase
Synonyms: Modulated Ramp;
Sawtooth+Chroma
Sawtooth+Chroma
See:
Sawtooth
Subcarrier
with
[Superimposed]
Glossary
SC
SDI Check Field
See: Colour Subcarrier
SC-H
A full field digital test signal consisting of two
parts - the upper half of the field is non-fully
saturated magenta (C=300h, Y=198h) and
serves to test equaliser operation, the bottom
half is grey (C=200h, Y=110h) )and serves to
test phase locked loop operation. The chief
characteristic of the SDI check field is that it
has a maximum low frequency content, thus
fully exercising the serial receiver slicing circuits
See: Subcarrier To Horizontal Timing
Synonyms: SDI Pathological Test Signal
Scanning
SDI Pathological Test Signal
Periodic movement of the aperture during TV
analysis or synthesis in accordance with a
defined specification, e.g. such as 625/50/2:1
Scanning Standard
See: SDI Check Field
SC lock
See: Colour Subcarrier Synchronisation
SC Timing
See: Subcarrier Timing
Scanning Standard
Set of parameters defining the scanning,
blanking and synchronisation processes.
Usually specified in shortform as three numbers
separated
with
a slash:
Number of Lines/Field (Frame) Rate/Interlace
Ratio; e.g. ’’625/50/2:1’’. Often the last part or
even two last parts are omitted, e.g. ’’625/50’’
or just ’’625’’
SDTV
Standard Definition TeleVision. Taken to mean
525-line or 625-line interlaced pictures.
SECAM
TV system in which the chrominance signal is
the result of frequency modulation of colour
subcarrier by a line alternated colour
difference signal Dr/Db. SECAM (SÉquence de
Couleur À Mémoire) system was proposed by
Mr. Henri de France
SECAM Chrominance Phase Switching
SCH Timing
The line-by-line and field-by-field variation of
initial phase of SECAM chrominance signal
following the specified pattern (in degrees) :
from line to line:
0, 0, 180, 0, 0, 180, . . .
or
0, 0, 0, 180, 180, 180, 0, 0, 0, . . .
from field to field: 0, 180, 0, 180. . .
See: Subcarrier To Horizontal Timing
Synonyms:
Screen Aspect Ratio
Switching; Phase Inversion; PI Sequence
Aspect ratio of the CRT or other display
device, possibly different from the picture
aspect ratio
SECAM Switch
SCH
See: Subcarrier To Horizontal Timing
SCH Phase
See: Subcarrier To Horizontal Timing
Chrominance
Phase
See: 2H
SDI
See: Serial Digital [Video] Interface
53
Glossary
SECAM-H
Self Key
Modern variant of SECAM system without
Vertical
Colour
Identification
Signals
(‘’Bottles’’); H stands in this case for Horizontal
colour sync, the bursts of un-modulated
chrominance on the line Back Porch are used
as a Dr/Db colour sequence sync reference.
Note: If in any doubt, signals produced in
SECAM-V with Bottles will always be usable on
SECAM-H equipment, but not vice versa. This
should not be confused with the two different
VHS recording methods for SECAM known as
SECAM-L and SECAM-ME
See: On-Lay
SECAM-L
1. Broadcast TV Standard used in France
2. Common label on multi-standard VHS
machines to denote operation in a VHS tape
format unique to France whereby frequency
modulated SECAM chrominance is down
converted utilising frequency division by a
factor of 4. The usual chroma processing
method in consumer VCRs is heterodyning.
Cassettes recorded on SECAM-L machines will
not play back in colour on any other type of
SECAM VCR
SECAM-ME
1. Common label on multi-standard VHS
machines to denote operation in a VHS tape
format similar to that used for PAL, hence its
common inclusion in low-cost multi-standard
VCRs. This format is in fact used throughout the
SECAM world except to France, where a VHS
system commonly known as SECAM-L is in use.
SECAM-L is actually the description of the
French Broadcast TV Standard. Cassettes
recorded on SECAM-ME will not play back in
colour on SECAM-L machines.
2. Sometimes incorrectly used to describe
SECAM-H without Bottles as opposed to
SECAM-V
SECAM-V
Older variant of SECAM system where the
Colour Identification Signal should be present
on the 9 lines in the vertical blanking interval.
Note: If in any doubt, signals produced in
SECAM-V will always be usable on SECAM-H
equipment, but not vice versa. This should not
be confused with the two different VHS
recording methods for SECAM known as
SECAM-L and SECAM-ME
54
Sequence
A sequence is defined as a series of states of
the DVE or mixer system called keyframes
(sometimes called shots in this context). The
data stored for each keyframe describes the
KeyFrame together with the speed and mode
of transition to the next one. Sophisticated
effects like those provided by DVE systems are
generally used in pre-programmed sequences
rather than live. This allows complex effects to
be
perfected
off-line,
and
ensures
repeatability. The sequence can be triggered
by external equipment, e.g. an editor using
GPI
Sequential Scanning
See: Progressive Scanning
Serial Digital [Video] Interface
Format, where 10-bit serialised video data are
transmitted via BNC type connector or fibreoptical connector with clock rate:
10 x 4 x 3.579=143 MHz (digital composite NTSC
and PAL-M), 10 x 4 x 4.433= 177 MHz (digital
composite PAL), 10 x 27=270 MHz (digital
component 4:2:2) or 10 x 36=360 MHz (Rec.
601 Part B, digital component)
Synonyms: Bit Serial Format; SDI
Serial-To-Parallel Converter
Device for the conversion digital video data
from serial interface format to parallel
interface format
Synonyms: De-serialiser
Serialiser
See: Parallel-To-Serial Converter
Serration
A gap between two adjacent broad pulses.
Normally its duration is the same as the
duration of line sync pulse
Set-Up
See: Pedestal
Glossary
Shallow Ramp
Sine X/X
A variant of the Ramp signal with reduced
amplitude, and set on a variable pedestal
level. Efficient for finding-out small scale nonlinearities, e.g. quantisation errors
Test signal in a form of section cut from the
sin(x)/x wave (the sin(x)/x waveform itself is, in
theory, infinitely wide), where x is a scaled time
co-ordinate. This waveform has the unique
feature of a uniform (flat) frequency spectrum
(up to a limit determined by the scaling
factor). Sin(x)/x waveforms check frequency
response, and are especially efficient for
automated measurements
Sharpness
Parameter describing the reproduction
edges and contours in a TV picture. Could
improved by edge enhancement,
opposed to Resolution, which can not
corrected by signal processing
of
be
as
be
Shot
A fragment of TV or film programme
appearing to come from one camera in one
uninterrupted period. If, during editing, a single
shot has a new section (another shot) inserted
in the middle, the result will then contain two
shot changes.
Sine-Squared pulse
Component of test signals with normalised half
amplitude duration (HAD), e.g. 2T-pulse. The
waveform shape is derived from the
expression:
2
sin (π t)/(2 HAD)
Synonyms: Sinus Squared Pulse
Sinus Squared Pulse
SID
See: Sine-Squared pulse
See: Source Identification Data
SIS
Side Panel Crop
See: Sound In Sync
Aspect ratio down conversion (e.g. 16:9 to 4:3)
with full vertical screen occupation and thus
symmetrical loss of side picture information left
and right.
Note that side panel crop is a particular case
of Pan and Scan
Side Panels
Parts of widescreen TV picture to the left and
right of an assumed conventional aspect ratio
(4:3) wanted picture
Signal Compression
See: Digital Compression
Signal To Noise Ratio
Measure of the relative amplitude of random
noise in the signal. It is usually expressed in dB
with reference to the nominal signal level
SNR (dB) = 20 log(nominal signal level/rms
noise level)
In the case of a video signal the nominal signal
level is assumed to be Nominal White level
(with reference to blanking level)
Skew
1. A digital effect that cause the rectangles in
displayed picture to appear as parallelograms
2. The Skew control on a VCR controls tape
tension around the head drum and hence
interchangeablity between tapes (it affects
the position of the visible head switch)
Skip-Field
A very common budget digital video effect
where the image is merely frozen for a
determined period and then instantly
updated at the beginning of the next period.
Live images may sometimes be used inbetween freezes
Synonyms:
Multi-grab;
Strobe;
Stroboscope
Slo-Mo
See: Slow-Motion
Synonyms: S/N; SNR
Silhouette [signal]
See: Key [signal]
55
Glossary
Slow-Motion
Solarisation
In essence, Slow-Motion is the apparent
slowing down of viewed images by playing
them back at a frame rate lower than that
which was used for recording. Implemented
most simply in video by the repetition of TV
fields or frames.
A digital video effect that re-maps the
luminance (and/or chrominance) levels of a
TV image, e.g. by expanding the central part
of the luminance scale and simultaneously
compressing or even inverting the dark and
light areas
Synonyms: Slo-Mo
Sound In Sync
Smear
Method of transmitting an analog video signal
together with accompanying sound by way of
insertion of pulses modulated by the audio
signal in the middle of Line Sync pulses
See: Lag
SMPTE
Society of Motion Picture and Television
Engineers. SMPTE commenced its activity in
North America, now it is a world-wide
organisation
uniquely
combining
broadcasters,
manufacturers
and
academicians. This body also issues its own
Recommendations
and
Recommended
Practices
SMPTE [Colour] Bars
Synonyms: SIS
Source Identification Codes
See: Source Identification Data
Source Identification Data
Part of internationally accepted Data Line
similar to IDS
Synonyms: SID; Source Identification
Codes
A Test Matrix pattern which consists of the
following (from top to bottom):
Sparkles
67 % of the field is occupied by 75 % Colour
See: Impulse Noise
Bars with bar eight missing (i.e. without Black)
The next 8 % is the so-called ’’New Chroma Set’’
bars
(Blue/Black/Magenta/Black/Cyan/Black/Whit
e) The remaining 25 % shows a sequence of -I,
White, Q, Black, and the ’’Black Set’’ signal
(version
of PLUGE)
SMPTE-125
SMPTE document equivalent to CCIR Rec 656
SNG
See: Satellite News Gathering
SNR
See: Signal To Noise Ratio
Soft Border
A Border with edges that are not sharp
transitions and so appear to be ’’blurred’’. The
extent of this ’’blurring’’ (rise-time of the key
signal) is usually adjustable
Synonyms: Soft Edge
Soft Edge
See: Soft Border
56
Glossary
Sparkles (Effect)
Spin
A digital video effect in which a stream of
particles appears to emerge randomly from
the edge of an object or effect wipe
boundary. The particles may consist of live
video or be colourised
A special case of the Rotation effect that
cause the displayed picture to appear as
spinning (in the screen plane) around the Z
axis (perpendicular to the screen plane)
Sparklies
In the DVE sense it describes a single coordinate control used for changing effects
parameters in the Z axis (perpendicular to the
screen plane)
A term describing the specific form of Impulse
Noise in video signals typical of marginal
satellite
reception.
Caused
by
FM
demodulator capture failure. Could be
suppressed by median filtering
Spatial Frequency
Value inverse to the period of the pattern in
the TV picture. It may be expressed in many
ways with different units of measurement: in
pixels per mm, cycles per active picture
height, in equivalent MHz of video signal
frequency, or in the internationally accepted
units of TV lines (tvl). E.g. for 625/50/2:1
scanning
standard
a
1 MHz video signal produces a periodic TV
screen pattern with a spatial frequency of
about 78 tvl
Spatio-Temporal
Generic term for parameters or processes that
take place in both space and time (spatial
and temporal) domains
Special Ramp
See: Ultrablack Ramp
Spectral Interleaving
A method of combining two or more signals
by adding them in such a way that each of
them occupies different slots in the frequency
domain. A problem with this method is that the
spectra thus created may partly overlap
making consequent complete separation
difficult if not impossible
Spinwheel
Synonyms: Z Wheel
Spline [Interpolation of Keyframes]
A curve whose shape is given by a set of
points plus other parameters such as tension. In
connection with Keyframes, splines are used to
specify the acceleration or deceleration of an
image from one keyframe to the next. The
smoothness of a spline is used to give natural
looking speed adjustments to objects. As one
example, when a ball bounces its speed is not
constant, but increases as it goes down and
decreases after it hits the ground and bounces
up. When the ball’s height reaches a peak, the
process repeats. By using splines as an
acceleration control, it is relatively easy to give
any video this smooth, natural looking
movement
Split [Colour] Bars
Matrix test pattern with upper 50 % occupied
by standard colour bars and remaining 50 % by Inverse Bars. This pattern is efficient for
detecting decoding artifacts, e.g. hanging
dots due to comb filtering
Split Field/Red
See: Bars and Red
SPG
See: Sync [Pulse] Generator
57
Glossary
SPLUGE
Standard
Variant of PLUGE test pattern
A set of rules or characteristics defining a
particular system or product. Some standards
are mandatory, but most are voluntary
Spotlight
A video effect that raises the video level in a
selected circular area of a picture. The result is
that the area appears as though it were
illuminated by a spotlight
Squeeze
Digital effect that cause the displayed images
to appear as though they are squeezed
(compressed) horizontally or vertically
Stair-stepping
See: Jaggies
Staircase
A test signal to measure non-linearity. Usually
with 5, 7 or 10 steps (also called risers)
Synonyms: Risers; Steps
Staircase with [Superimposed]
Subcarrier
Staircase test signal with subcarrier burst to
measure differential gain and differential
phase
Synonyms: Modulated Staircase
Standards Conversion
The conversion of video signals between
different Scanning Standards, for instance
NTSC to PAL conversion, or 1250/50/2:1 to
625/50/2:1 conversion
Standing Dots
Cross-Luminance near sharp saturated vertical
colour edges, e.g. at the boundaries between
bars in the colour bar pattern. The expression
is mainly used in NTSC, in PAL it is called
Dot Crawl
Star [Display]
A special display mode showing component
video signal gamut on a waveform monitor.
The three signals R, G, B (usually matrixed from
Y, Pb, Pr) are shown as three diamonds
plotting R against B, R against G and G against
B respectively. The centre of the display
corresponds to Reference Black. The sides of
the diamonds show the boundary of legal
colour space
Static Resolution
Resolution when there is no movement in the
TV picture. I.e. resolution assessed on stationary
image
Steps
See: Staircase
Still Store
A device to store one or several static TV
pictures (frames)
Streaking
Artifact due to non-uniformity of the video
path frequency response in low or medium
frequency regions
Strobe
See: Skip-Field
Stroboscope
See: Skip-Field
58
Glossary
Subcarrier Burst
Symmetry
A burst of chrominance signal with a phase
defined by the TV system specifications,
inserted in the line blanking intervals to provide
the reference for
Colour Subcarrier
Synchronisation
See: Double Mirror
Subcarrier Synchronisation
See: Colour Subcarrier Synchronisation
Subcarrier Timing
Relative timing of two colour subcarrier signals
maintained in Synchronism. An error in SC
timing results in colour or hue shifts. The
subcarrier timing adjustment is sometimes
labelled ’’Burst Phase’’
Synonyms: Colour Timing; SC Timing
Subcarrier To Horizontal Timing
1. Phase of colour subcarrier at the Line Datum
2. Phase of colour subcarrier at the Field
Datum, measured by extrapolating the colour
burst signal to the Line Datum point. This type
of timing is particularly important in editing
applications since SCH differences can
introduce horizontal shifts in a composite edit
environment. For instance, in a digital PAL/D2
interface ’’zero SCH phase’’ means that at the
Field Datum, the U component sinusoid is
falling and is at a zero-crossing point
Sync
See: Synchronisation Pulses
Sync [Pulse] Generator
Device generating synchronisation pulses
Synonyms: SPG
Sync [tips] Level
Composite signal level transmitted during the
flat parts of the sync pulses
Sync Pulses
See: Synchronisation Pulses
Sync Timing
Relative timing of two sets of horizontal and
vertical sync pulses held in Synchronism. An
error in sync timing results in horizontal and
vertical shifts of TV picture. The term is often
incorrectly identified with horizontal timing
only. Sometimes the words are used to stress
the lack of subcarrier timing or non-zero SCH
timing.
Synchronisation
Achievement and subsequent holding of
Synchronism
Synonyms: SC-H; SCH; SCH Phase; SCH Synchronisation Pulses
Timing
Sweep
Test signal in form of a line or field/framerepetitive sinusoidal waveform with frequency
linearly changing within a defined range. This
signal serves to measure frequency response
Switcher
See: Video Mixer
Switching Area
Timing window on a specific TV line where
Vertical Interval Switching is to be performed.
According to the SMPTE document RP168 it
must occur between 25th and 35th
microsecond on line 10 for the 525 system and
between
25th and 35th microsecond on line 6 for the
625 system
1. General term, including any pulses, serving
to provide Synchronism
2. Same as Synchronisation Signal. Sometimes
the use of this term implies that the pulses are
not as thoroughly specified as signals
Synonyms: Composite Sync; Sync; Sync
Pulses
Synchronisation Signal
Signal carrying information about frequencies
and phases of the horizontal and vertical
scanning. Serves to assist Synchronisation
Synonyms: Mixed] [Composite] Sync; S.
Switching Matrix
See: Matrix Switcher
59
Glossary
Synchroniser
Tartan [Colour] Bars
A device performing variable delay function
from minimal up to one whole frame, for the
purpose of Synchronisation. Slight differences
between the Frame Rates of incoming and
reference
signals
can
usually
be
accommodated.
Note that if the incoming and reference frame
rates are different then occasional fields must
be added or dropped, which can cause
visible jumps. It is for this reason that VCRs are
often field-locked to zero, the long-term frame
rate difference. Occasionally the word
’’synchroniser’’ is used to describe a Line
Synchroniser, without a framestore
A Test Matrix consisting of several (usually 8)
bands, each contains colour bars with a
different sequence of colours, together they
cover all, or almost all, possible horizontal and
vertical colour transitions. Useful to test twodimensional chrominance processing devices,
e.g. comb filters
Synchronism
1. Equality of frequencies and phases
between two or more scanning processes
2. Equality of frequencies with fixed phase
differences between two or more scanning
processes
T [Unit]
The measurement unit describing the width of
sine squared pulses and bar edges with
reference to the nominal system bandwidth.
T =1/(2xB), where B is assumed bandwidth - for
countries using the 625 line standard it was
agreed to set T=100 ns, and for countries using
the 525 line standard T=125 ns
Take [Editor]
1. In general a ’’Take’’ is a continuous piece of
action from one scene used to provide the
source material (or ’’rushes’’) for editing. A
single scene may require several ’’takes’’
before the director is satisfied with the results. A
single take may provide rushes from more than
one camera
2. In a DVE or Vision Mixer a ’’Take’’ button
(which may be remote controlled) will usually
trigger a predefined Transition. In this context,
’’Take’’ is sometimes called ’’Auto-Transition’’
Tally
An indication that a particular device is ’’on
line’’. This indication, usually a lamp or LED, can
be on the switcher itself, or on a remote piece
of equipment, such as a monitor or a camera.
A sources tally is activated automatically
when the source is selected via the mixer’s
program bus
60
TBC
See: Time Base Corrector
Telecine
Device performing TV analysis of motion
picture films and occasionally diapositive
(reversal) stills
Teletext
Broadcast TV service providing alpha-numeric
and graphic information by transmission of
Data Lines within TV signal
Teletext Line[s]
1. Line[s] in the vertical blanking interval
allocated for Teletext service
2. Coded pulse sequences inserted in one or
more lines of the vertical blanking interval and
carrying Teletext data
Television
Transmission of moving images by electrical
means
Synonyms: TV
Television Line
Commonly used measure of spatial frequency
of periodic pattern in a TV picture expressed
as a ratio of picture height to the half period of
the pattern. E.g. for 625/50/2:1 scanning
standard a 1 MHz video signal produces a
periodic TV screen pattern with a spatial
frequency of about 78 tvl. See also: Line
Synonyms: TV line; tvl
Temporal Alias
An alias caused by violation of sampling limit
(Nyquist Limit) on the sampling in time at frame
or field rate. The classic example is in images
of spinning wagon wheels that appear to be
turning backwards
Glossary
Test Card
Time Base Correction
Generic term for frame-based picture created
by optical or electronic means for purpose of
test (e.g. the universal test chart with circles
and many other components). Normally the
term is used to describe the test pattern
radiated by TV transmitters outside normal
broadcast hours
Modification of TV signal timing parameters
with the purpose of providing a consistent and
stable Time Base, overcoming variations in
input signal due to physical tape distortions
etc.
Synonyms: Test Chart
Test Chart
See: Test Card
Test Lines
See: Vertical Interval Test Signals
Test Matrix
Test pattern composed from several horizontal
bands each occupied by test signal of some
type; does not contain two-dimensional
components like circles, etc. Note that such
patterns are often simply referred to as ’’matrix’’
Time Base Corrector
Device performing a Time Base Correction
function often with many other features, e.g.
Transcoding function as well as noise
reduction
Synonyms: TBC
Time Datum
See: Line Datum
Timebase
Synonyms: Line-based Test Pattern
1. In a narrow sense: an oscillator circuit
providing the deflection signals to a CRT or
pickup tube
2. In a wider sense: a time variant function,
describing the variation of signal phase with
regard to some time reference
Test Pattern
Timing
Generic term for picture created by optical or
electronic means for purpose of test. Patterns
may be line repetitive (e.g. EBU Colour Bars), a
matrix of line-repetitive patterns (e.g. SMPTE
Colour Bars which have three distinct regions)
or frame-based test patterns (e.g. the universal
test chart with circles and many other
components)
1. Same as Synchronisation
2. Temporal phase of a signal with reference
to another signal
Title Key
See: Caption Key
Trail
Tiles
A special Recursive Effect separate from the
main video path, where selected or keyed
fragments of previous images are repeated
infinitely usually with a small positional offset
and a change in video parameters. The live
image is normally in the foreground. This gives
the appearance of a Trail ’’flowing’’ away from
the object(s). If no positional offset is selected
then the trail will only be visible as a reminder
of where the objects were after they have
moved
See: Pixellation
Trailing Dots
Test Signal Pedestal
Auxiliary test signal component in the form of a
grey level background (e.g. 50 % of Reference
White). Note that this parameter has little in
common with the Pedestal (Set-Up) of NTSC
composite video
Three Stage Mixer
See: Triple Re-Entry Mixer
Tilt
See: Bar Tilt
Cross-luminance near sharp saturated moving
colour edges, due to the failure of the
chrominance filter in the temporal dimension
and thus providing incomplete Y/C separation
61
Glossary
Trajectory
TRS
In general a trajectory is any path between
two points although intermediate points
should be given to describe complex
trajectories. Hence in the context of a DVE, a
trajectory is created by a series of Keyframes
which have been defined by the operator
Timing Reference Signal, usually in form of
digital data. E.g. in composite digital systems it
is four code word sequence.
Transcoding
1. The conversion of video signals with different
Colour TV Systems but with the same scanning
standard, for example PAL to SECAM or
SECAM to PAL
2. Often used in North America (particularly
Quebec) to mean Standards Conversion
Transition
1. A Vision Mixer changeover operation from
one source picture to another picture, or from
one Keyframe to another
2. An abrupt change of video signal level, e.g.
’’green-magenta transition’’ in the centre of a
colour bar pattern
Transport Stream [MPEG]
A bitstream packaging Elementary Streams
together. It can accommodate several
programmes with independent clocks.
Transport streams have fixed-length packets
and are intended for transmission over errorprone channels. This stream is often called
simply "the MPEG signal".
Tri-Level Sync
Synchronisation signal containing adjacent
pulses of opposite polarities. Line start moment
is defined by zero level crossing point,
providing improved hum and noise immunity.
Tri-sync is commonly used in HDTV systems
Synonyms: Bipolar Sync; Tri-Sync
Tri-Sync
See: Tri-Level Sync
Triple Re-Entry Mixer
A Vision Mixer with three Mix Effects buses, any
one of which can be used as an input to the
others. This allows more layers of processing to
take place in a single pass through the system
Synonyms: Three Stage Mixer
TRS-ID
Timing Reference Signal Identification: a code
word defining the colour frame number and
possibly line number
Tumble
A combination of gradual vertical Squeeze
and Mirror effects that cause the displayed
picture to appear as though it is rotating
about horizontal axis
Synonyms: Turn
Turn
See: Tumble
TV
See: Television
TV Analysis
The process of sequential [in time]
transformation of the colour or brightness of
image elements into electrical signal[s]
Synonyms: Analysis; Pick-Up
TV Centre
The main site of an enterprise producing and
transmitting TV programmes
TV Field
Part of TV Frame scanned during one vertical
cycle of TV Aperture movement. In the case
of progressive scanning TV field is equal to
TV frame
TV Frame
1. The track of total cycle of the periodic
movement of TV aperture (same as TV raster)
2. Time interval during which the total cycle of
scanning takes place (frame period)
TV Image
Image of the object[s] resulting from the
display process
Synonyms: TV Picture
TV line
See: Television Line
TV Picture
See: TV Image
62
Glossary
TV Picture Artifact
U, V
Visible defect in a TV picture due to a
shortcoming in a process
Colour difference signals scaled to provide
necessary PAL chrominance:
U = 0. 493 (B-Y)
V = 0. 877 (R-Y)
Note: Do not confuse these signals with the Pr
and Pb signals used for component
interchange. The U and V signals only exist
prior to PAL modulation or after demodulation
Synonyms: Artifact [of a TV Picture]
TV Raster
Two-dimensional track of total cycle of the
aperture scanning (vertical and horizontal
combined)
TV Studio
Ultrablack Ramp
1. In the strictest sense: a specially equipped
room with cameras and microphones used for
production of TV programmes
2. In a wider sense: any enterprise dealing with
production and post-production of TV
programmes
A variant of the Ramp signal with an extended
range of levels including levels below black
Synonyms: Special Ramp
Up Conversion
See: Display
Standards conversion where the Line Rate of
the output standard is significantly higher that
of the input standard, e.g. 625/50/2:1 to
1250/50/2:1 or 625/50/2:1 to 625/50/1:1
TV System
Up-Sampling
See: Colour TV System
Sampling Rate Conversion to increase the
sampling rate, e.g. from 13.5 MHz to 27 MHz
TV Synthesis
tvl
See: Television Line
Tweens
See: In-betweens
Twitter
One of the most significant artifacts of
interlaced pictures. Fine detail or near
horizontal lines appear to jump up and down
due to the two fields alternately representing a
different part of the detail, thus some of the
detail is only visible half the time and some the
other half, creating a crude “ wobble“
animation effect
Two Stage Mixer
See: Double Re-Entry Mixer
V-Timing
See: Vertical Timing
Valid Ramps
A component video test signal containing
three ramps, covering correspondingly the
total level range of the Y, Pb or Pr channels,
each ramp is accompanied by smaller ramps
in the two other channels to keep colours
within the valid range of R, G, and B levels
from Reference Black to Reference White
Valid Staircases
Same as Valid Ramps with fixed increments
instead of continuous rise
VD
See: Vertical Drive
VDA
See: Video Distribution Amplifier
Vector Assignment
Operation of signal post-processing in motion
estimator which attribute Motion Vectors to
pixels by creating boundaries around sets of
pixels having the same motion.
Venetian blinds
See: Hanover Bars
63
Glossary
Vertical [Blanking] Interval
Vertical Interval Test Signals
Time interval during which vertical blanking
is applied. E.g. , in 625 line systems the Vertical
Blanking width is 25 lines plus Horizontal
Blanking Interval
Test signals inserted in the lines of the vertical
blanking interval, defined by the TV standard,
e.g. for the 625 standard the CCIR together
with the EBU issued the formal specifications
for the signals inserted in lines 17, 18, 330 and
331 - hence these VITS are often called CCIR17, CCIR-18, CCIR-330 and CCIR-331
Synonyms: Field Blank; Vertical Blank
Vertical [Interval] Time Code
Coded pulse sequences for the purpose of
time moment identification, inserted in one or
more TV lines (usually in the lines of the vertical
blanking interval)
Synonyms: VITC; VTC
Scanning producing TV fields (or frames), i.e.,
scanning in a vertical direction
Field rate Blanking. Note that the term "Frame
blanking" is only applicable to progressive
scan systems
Vertical Drive
Sync pulse with leading edge marking the start
of Vertical Blanking Interval. Sometimes
incorrectly called ’’Vertical Sync’’
Synonyms: FD; Field Drive; VD
Vertical Frequency (informal usage)
See: Frame Frequency
Vertical Interval Reference Signals
Signals inserted in the lines of the vertical
blanking interval, as defined by a TV Standard.
For use in TV receivers for automatic correction
of transmission chain distortions
Synonyms: VIR; VIRS
Vertical Interval Switching
Video signal switching performed within the
Vertical Blanking Interval to minimise the
visibility of switching artifacts
Ratio of active image area height to the
display screen height
the vertical blanking interval. The vertical sync
group serves to enable synchronism of vertical
scanning. Usually includes equalising pulses
and broad pulses (field synchronisation pulses)
Vertical Timing
Relative timing (in discrete lines) of two sets of
vertical sync pulses held in Synchronism. An
error in V-timing results in vertical shifts of the TV
picture
Synonyms: V-Timing
Vertical-Temporal Sampling
Two-dimensional sampling that occurs in every
TV signal due to individual frames (which
sample in time) and individual lines (which
sample in the vertical direction). Like all
sampling processes, this sampling can cause
aliases unless properly pre-filtered
Video Band
See: Baseband
Video Distribution Amplifier
Device for the amplification and distribution of
one video signal to several destinations,
sometimes combined with a cable equaliser
Synonyms: VDA
64
Frame
Vertical Sync Group
Frame A group of pulses occupying several lines in
Blanking
Synonyms: Back Porch Switching
Scanning;
Vertical Screen Occupation
Vertical Blanking
Blanking;
Field
Scanning (informal usage)
See: Vertical [Blanking] Interval
Field
Vertical Scanning
Synonyms:
Vertical Blank
Synonyms:
Synonyms: ITS; Test Lines; VITS
Glossary
Video Effect
VITC
Any deliberate change of the TV picture for
artistic purposes achieved by video signal
processing, including compositing of the
resulting picture from several sources. Mixing
and wipes are examples of ’’video effects’’. In
a narrow sense the expression is often used to
denote the use of a DVE effect.
See: Vertical [Interval] Time Code
Video Mixer
1. In a narrow sense: Device for the on-line
combining of two or more TV pictures into one
output picture by linear algebraic summation
2. In wider sense: Device for preselection from
several sources, manipulation (e.g. with built-in
DVE) plus the on-line combining of two or
more TV pictures in an output picture. This
device is sometimes called ’’mixer-switcher’’ or
’’production switcher’’
Synonyms:
Production
Video Processor
See: Processing Amplifier
Video Signal
carrying
See: Vertical Interval Test Signals
VTC
See: Vertical [Interval] Time Code
Warp
A digital video effect involving any 2 or 3dimensional change in shape (deliberate
geometric distortion) of an input picture.
Wash
See: Graduated Matte
Wedge [Pattern]
A test pattern consisting of alternating black
Switcher; and white stripes (usually from 3 to 7, on a grey
Switcher; Vision Mixer
Any signal
displayed
VITS
information
to
be
Vidiplex
A simple ’’multiplexing’’ method, where two
different TV programme signals are transmitted
sequentially in the odd and even fields of the
TV Frame. Equally suitable for transmission of
NTSC, PAL or SECAM signals
Viewed Picture Format
Combination of screen aspect ratio and
picture aspect ratio
VIR
See: Vertical Interval Reference Signals
VIRS
See: Vertical Interval Reference Signals
Visibility of Line Structure
Artifact of television raster display due to
coarseness of the line pitch in comparison with
the Aperture size
background), which vary in repetition pitch so
as to give the appearance of a wedge. There
are several variants of this pattern: with linear
rise of spatial frequency and curved stripes
(hyperbolic wedge) or with linear decrease of
the spatial period and straight stripes (linear
wedge), with rectangular shape of the
waveforms across the wedge (line mire) or
with sinusoidal shape (sinusoidal mire). The
wedge patern is usually seen as one of the
many components of a resolution test chart
Synonyms: Wedge Mire
Wedge Mire
See: Wedge [Pattern]
Weighted Noise
Noise put through special filter to shape its
spectrum in order to take into account the
subjective visibility or effect of different
frequency components.
Weighted Signal To Noise Ratio
Ratio of the nominal signal amplitude to the
Weighted Noise rms value expressed in dB.
Usually this value is 10-16 dB higher than unweighted SNR
Synonyms: Weighted SNR
Weighted SNR
Vision Mixer
See: Weighted Signal To Noise Ratio
See: Video Mixer
White Clipper
See: White Limiter
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Glossary
White Level
Wipe
See: Reference White Level
Device preventing a video signal being higher
that some threshold level, usually set slightly
above Reference White Level
1. Synthetic key pattern specially generated to
define the boundaries of Zonal Mixing, e.g.
’’diagonal wipe’’ or ’’diamond wipe’’
2. Transition by control of wipe parameters.
E.g. a simple wipe from left to right by altering
the wipe horizontal positions parameters
Synonyms: White Clipper
WSS
Wide Screen Signalling
See: Wide Screen Signalling
White Limiter
1. Method of transmission of information about
aspect ratio and some other parameters
towards TV receiver by data inserted in the
vertical blanking interval.
2. Data embedded in the video signal
containing information on the image aspect
ratio and its position, on helper signal
presence, on the position of the subtitles and
on the camera/film mode selection. In 625lines systems, e.g. in the PALplus system, WSS
data are transmitted during first half of TV line
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Synonyms: WSS
Widescreen
Viewed picture format with aspect ratio higher
than in conventional TV and full screen
occupation, e.g. 16:9
Window
1. Test pattern in a form of white box on black
or grey background. A change of window size
provides an easy way to control the average
picture level.
2. A mode of test pattern generation where
the main test signal is gated by a window
signal to provide a grey or black background
at the main test perimeter
Window mode [of HDTV down
conversion]
Mode of HDTV Down Conversion where the
output TV picture is produced from part of an
HDTV source picture with on-line control of its
size and position
Synonyms: Zoom mode
XVGA
Originally used to describe a custom display
format, now widely adopted as the name for
1024x768 resolution
Y.
See: Luminance [Signal]
Y/C [Interface]
See: Y/C Connection
Y/C Connection
Popular semi-professional two-signal interface
format, where Y is a luminance component
and C is a chrominance component at NTSC
or PAL colour subcarrier frequency. Because
the C signal is transmitted separately there are
no cross-effects, so the decoded picture looks
almost as good as the original. The Y/C
interface is used in S-VHS and 8 mm VCRs, plus
related equipment
Synonyms: S-Video; Y/C [Interface]
Yaw
A term borrowed from aeronautics to describe
the effective static rotation of the aircraft
about an imaginary vertical pin. Thus the
aircraft can be moving forward but not
necessarily facing forward but offset by the
yaw angle. In digital video effects this term
can be used to describe the positioning of the
effect (rotation about the Y axis)
Z Wheel
See: Spinwheel
Zonal Mixing
See: In-Lay
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Glossary
Zone Plate [Test] [Pattern]
Zoom mode
Sweep test pattern with linear or non-linear
change of spatial frequencies in two
orthogonal directions (plus the temporal
direction in some variants). The two main zone
plate patterns used are Circular (Bulls Eye) and
Hyperbolic
See: Window mode [of HDTV down
Zoom
Synonyms: Expand
Optical or digital effect where the image is
altered in size, while remaining centred about
a defined point. The zoom may either increase
or decrease the size of the objects in the
image, ignoring its borders or edges (which
are a separate consideration)
conversion]
Zoom-In
Expansion of the picture details within the
zoomed picture area
Zoom-Out
A Zoom effect with objects being decreased
in size
Synonyms: Compression; Reduction
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The following list will be of interest to readers wishing to go beyond the
subject matter of this volume.
From the Snell & Wilcox Handbook series:
The Engineer’s Guide to Decoding and Encoding
1 900739 01 1
- essential reading for those faced with the problem of interfacing today’s
component equipment with composite signals.
The Engineer’s Guide to Standard Conversion 1 900739 03 8
- shows that standards converters are not all alike and how to compare
them.
The Engineer’s Guide to Motion Compensation
1 900739 02 X
- companion to the Standards Conversion handbook which shows how
motion compensation transforms standards conversion.
The Engineer’s Guide to Compression
1 900739 06 2
- in addition to the theory, practical advice is given about getting the best
out of compression systems.
The Snell & Wilcox Guide to Digital (NTSC)
1 900739 04 6
The Snell & Wilcox Guide to Digital (PAL)
1 900739 05 4
- easily understood introduction to digital television production systems.
Subjects include Non-linear, DVTRs, Compression, SDI, Testing.
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Printed and Published by Snell & Wilcox Ltd, England
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