SWE 116 : Multimedia data processing / COMPUTER GRAPHICS
➢ Computer graphics: 3 credits (45 hours); L, T, SPW
1. Digital images ▪ Bitmap images ▪ Vector images ▪ Characteristics of bitmap images ▪ Image
compression ▪ Final improvements of images ▪ Practicals on the creation buttons and images for
the Web
2. Sound ▪ Definition of sound ▪ Characteristics of sound ▪ Digitalization of sound ▪ Mono and
stereo sound ▪ Size of a sound file ▪ Sound compression
3. Video ▪ Definition of video ▪ Analogue video ▪ Digital video ▪ Compression of digital video
(notion on Codec)
Introduction
Multimedia in principle means data of more than one medium. It usually refers to data representing
multiple types of medium to capture information and experiences related to objects and events.
Commonly used forms of data are numbers, alphanumeric, text, images, audio, and video. In
common usage, people refer a data set as multimedia only when time-dependent data such as audio
and video are involved.
Computer Graphics
Computer graphics is the field of computer science that deals with generating and manipulating visual content using
computers.
This encompasses a wide range of applications, including: 2D & 3D Graphics, Rendering, Animation, Visualization,
User Interfaces etc.
Advantages of Computer Graphics
Enhanced Visualization: They provide clear and detailed visual representations of complex data, making it easier
to understand and interpret information.
Realism and Engagement: High-quality graphics create immersive experiences in entertainment, education, and
training, capturing audience attention and enhancing engagement.
Speed and Efficiency: Graphics software allows for rapid design iterations and modifications, significantly
speeding up the creative process compared to traditional methods.
Cost-Effective Prototyping: Creating digital prototypes reduces material costs and time, allowing for better testing
and refinement before physical production.
Flexibility: Computer graphics can easily be modified and adapted for various applications, making them versatile
for different industries and purposes.
Accessibility: Digital graphics can be shared easily across platforms, reaching wider audiences and facilitating
collaboration regardless of geographical locations.
Improved Communication: Visual aids can transcend language barriers, conveying ideas and concepts more
effectively than text alone.
Interactivity: Many computer graphics applications allow for user interaction, enhancing user experiences in fields
like gaming and web design.
Opportunities computer graphics offers
Computer graphics offers a diverse range of opportunities across various sectors. Here are some key areas:
1.
2.
3.
4.
5.
6.
Video Game Development: Roles in game design, 3D modeling, animation, and visual effects for interactive
entertainment.
Film and Animation: Opportunities in animation studios for creating visual effects, character design, and
3D animation in movies and television.
Graphic Design: Careers in branding, advertising, and marketing, focusing on creating visuals for print and
digital media.
Web Design: Designing user interfaces (UI) and user experiences (UX) for websites and applications,
integrating graphics to enhance usability.
Architectural Visualization: Creating 3D renderings and walkthroughs for architects and real estate
developers to visualize projects before construction.
Medical Visualization: Working with medical imaging technologies to create visual representations of
complex biological data for diagnosis and research.
7.
Data Visualization: Designing visual representations of data for businesses and organizations, making
complex information more understandable.
8. Virtual Reality (VR) and Augmented Reality (AR): Developing immersive experiences and applications
that blend digital graphics with the real world.
9. Education and Training: Creating educational content and simulations that use graphics to enhance learning
experiences in various fields.
10. Research and Development: Engaging in innovative projects in computer graphics technology, exploring
new rendering techniques, graphics hardware, and software applications.
Definition of some Terms
1) Multimedia
Multimedia refers to the integration of various content forms, including text, audio, images, animations, video, and
interactivity, to create engaging and dynamic presentations. It combines different media types to enhance
communication and information delivery.
Types of Media:
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Text: Written content that provides information or context.
Audio: Sound elements, including music, voiceovers, and sound effects.
Images: Static visuals like photographs, illustrations, and infographics.
Animation: Moving images that can illustrate concepts or tell stories.
Video: Recorded moving images that convey information or entertainment
2) Multimedia Application
A multimedia application is a software program that combines multiple forms of media—such as text, audio, images,
video, and animation—to create interactive and engaging content. These applications can be used for various purposes
across different fields. E.g Video Editing Software, Social Media Platforms: Apps like Instagram and TikTok etc
3) Multimedia System
A multimedia system is a computing system that integrates multiple forms of media—such as text, audio, images,
video, and animations—to create, store, process, and present information. These systems are designed to manage and
deliver rich content in an interactive manner.
Key components of a multimedia system
Hardware:
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Computers or Servers: The central processing units that run multimedia applications.
Input Devices: Such as microphones, cameras, and scanners for capturing audio, video, and images.
Output Devices: Monitors, speakers, and printers for displaying and playing back multimedia content.
Software:
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Multimedia Authoring Tools: Applications for creating multimedia content (e.g., Adobe Creative Suite).
Media Players: Software for playing back audio and video files (e.g., VLC Media Player).
Editing Software: Programs for editing text, images, audio, and video.
Content:
The actual multimedia elements, such as videos, audio files, graphics, and animations, that are used in the system.
Storage:
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Systems for storing large multimedia files, including hard drives, cloud storage, and databases.
Networking:
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Infrastructure for transmitting multimedia content over the internet or local networks, enabling streaming and
sharing.
Features of Multimedia System
Integration of Multiple Media Types: Multimedia systems combine text, audio, images, video, and animations
to provide a richer and more engaging experience.
Interactivity: Users can interact with the content, making choices that affect the outcome or the information
presented, enhancing user engagement.
Real-time Processing: Many multimedia applications require real-time processing to deliver smooth playback and
interaction, especially in gaming and video conferencing.
High Bandwidth Requirements: Multimedia content, particularly video and audio, often requires significant
bandwidth for transmission and storage, necessitating efficient network capabilities.
Synchronization: Effective multimedia systems synchronize various media elements (like audio and video) to
ensure they work together seamlessly.
Non-linear Navigation: Unlike traditional linear presentations (like a book), multimedia systems often allow users
to navigate content in a non-linear fashion, enabling personalized experiences.
Rich User Interfaces: They typically feature visually appealing and user-friendly interfaces that enhance the
overall experience and accessibility.
Storage and Compression: Multimedia systems utilize various storage techniques and compression algorithms to
manage large media files efficiently, ensuring quick access and minimal load times.
Multi-user Capability: Many multimedia systems support multiple users, allowing for collaborative projects or
shared experiences, especially in educational and gaming contexts.
Adaptability: They can be tailored for different platforms and devices, such as smartphones, tablets, and
computers, ensuring accessibility across various environments.
1) Digital Images
A digital image is a representation of a real image as a set of numbers that can be
stored and handled by a digital computer.
A digital image consists of a large number of small spots of color. These spots are
called pixels, a contraction of “picture elements.” When displayed on a monitor or printed
on paper, pixels are so small and so closely packed together that the collective effect on
the human eye is a continuous pattern of colors. However, if you look closely at magnified
computer displays, for example as produced by projectors, you can sometimes see
individual pixels as small rectangles.
* Bitmap or Raster Images: Raster images are the types of images you get from
a digital camera or the camera on your phone; the same goes for images pulled from
documents via scanner. The common image file types on the internet – jpgs, gifs,
and the like – are generally raster images. Any image that’s made up of pixels – the
tiny, individually-colored units that combine to make the whole image – is raster.
This is why these images blur when enlarged: A close view of the image reveals
the individual pixels that make the image and breaks the appearance of a smooth
transition across these pixels. This blurring is called pixelating.
Raster images are still the best form of image for photographs, especially regarding
editing functions from software like Photoshop, designed to work well with the
pixel-based format. It’s possible, of course, to print raster images at different sizes,
but the pixel count in the image needs to meet a minimum that correlates with the
size of the piece being printed.
* Vector Images: Vector images are different from raster images. First, they aren’t
made up of pixels. Vector images, which are generally made or translated through
illustration software, are actually made up of individual lines and shapes (called
objects) that combine to make a whole image, through mathematical calculations
that define the shapes and directions of the lines.
Vector art is not created through a camera; instead, it’s created through illustration
software like Adobe Illustrator and Corel Draw and commonly saved as .ai, .pdf,
.eps and .svg files.
Although vector images lack the complex details that you can create with photographs (raster
images), vector art shines in it’s own way: Recall the earlier reference to pixelation. You won’t
find any in a vector image, no matter what size the image is stretched or shrunk to.
This is why vector images are an excellent format for the creation of printed products such
as postcards, brochures, banners, and signs. Logos or illustrations as a vector image can be
stretched to any size for printing without losing image quality or ever seeing any blur or pixelation,
which means your graphics will look great regardless of whether they’re printed on small business
cards or jumbo-sized banners.
The Bottom Line
In short, raster images are best for detailed images like photographs and can include more varied
shades of colors and gradients as they utilize pixels. Raster images need to be printed in the
appropriate size and medium for the image.
Vector images don’t utilize pixels, work well for things like logos and illustrations, and can be
printed at any size. Vector images scale infinitely, which makes them the perfect format for
company logos that will be applied on various mediums.
Knowing the difference can help you understand the best choice of image for any printing project
your business takes on. Your U.S. Press account manager can help you with any further questions
or details regarding raster images, vector images, and how to use both to the best benefit of your
company.
Assignment
Bring out 5 Differences between Vector and Bitmap Images.
* Characteristics of Bitmap Images
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Bitmap graphics are resolution dependent - they have a fixed resolution based on the
number of pixels they consist of.
Bitmap graphics handle complex, multi-coloured images well - This is why they're
typically used for digital photography and other detailed graphics.
Bitmap graphics can become pixelated when enlarged - Increasing the size of a bitmap
graphic can often result in a loss of quality.
Bitmap graphics have larger file sizes - Compared to vector graphics, bitmap graphics
tend to have larger file sizes as they store individual colours for each pixel.
* Image Compression
Image compression is a process applied to a graphics file to minimize its size in bytes without
degrading image quality below an acceptable threshold. By reducing the file size, more images
can be stored in a given amount of disk or memory space. The image also requires
less bandwidth when being transmitted over the internet or downloaded from a webpage,
reducing network congestion and speeding up content delivery.
Types of image compression
The methods used to compress image files typically fall into one of two categories: lossy and
lossless.
1) Lossy compression reduces an image file size by permanently removing less critical
information, particularly redundant data. Lossy compression can significantly reduce file size,
but it can also reduce image quality to the point of distortion, especially if the image is overly
compressed. However, quality can be maintained when compression is carefully applied.
One of the challenges with lossy compression is that it's irreversible. Once it has been applied to
an image, that image can never be restored to its original state. If lossy compression is applied
repeatedly to the same image, it gets increasingly distorted. That said, lossy compression has
proved to be a valuable strategy for the web, where a moderate amount of image degradation can
often be tolerated
Note: The most common example of lossy compression is JPEG, an image compression format
used extensively on the web and in digital photography. This widely recognized format is
supported by numerous tools and applications. Additionally, compression can be applied in
degrees, making it possible to use JPEG compression that best strikes a balance between file size
and quality.
2) Lossless Compression method applies compression without removing critical data or
reducing image quality and results in a compressed image that can be restored to its
original state with no degradation or distortion. However, lossless compression doesn't
reduce the file size nearly as much as lossy compression, offering little advantage in
terms of storage space, network bandwidth or download speeds. Lossless compression is
generally used in situations where image quality is more important than disk space or
network performance, such as for product images or to showcase artwork.
Note:
- One of the most common lossless formats is PNG, a widely used format that reduces file size
by identifying patterns and compressing those patterns together. Although PNG files are
generally larger than JPEG files, websites use them extensively when more image detail is
needed, such as for logos, icons, screenshots or images with text. Another familiar lossless
format is BMP, a proprietary approach to image compression introduced by Microsoft and used
primarily for Microsoft products, particularly Windows computers.
- GIF is compression format that falls into the lossless category, although there is some
confusion as to whether it is lossy or lossless. GIF images are limited to 256 colors, so
converting an image with more colors to GIF results in a loss of quality, which is sometimes
attributed to lossy compression. But the compression algorithms used by GIF are lossless. If
quality is lost, it's due to issues related to converting the file. Currently, the GIF format is used
primarily for simple videos and animations.
- A compression format that's making headway is Google's WebP, an image format developed
exclusively for the web. Unlike most compression techniques, WebP supports both lossless and
lossy compression, making it highly versatile. WebP images generally use less disk space than
other formats but offer comparable quality. Most major browsers support WebP images.
Compression can also be used for non-image file types such as text or program files, but its use
tends to be limited to lossless compression. In text and program files, it is crucial that
compression be lossless because a single error can damage the meaning of a text file or cause a
program not to run. The zip file format is an example of lossless compression commonly used
for text files or even entire directories of files.
In image compression, a small loss in quality is usually not noticeable. In situations where there
is some tolerance for loss, greater compression can be applied to files than when there is no
tolerance for loss. For this reason, graphic images can usually be compressed to a much greater
degree than text or program files.
Final Improvements of Images
There's a reason it's said that a picture is worth a thousand words. And when it comes to building
your brand, images are a great way to communicate clearly within your audience. Hence the
reason, it is good to have a good Image Resolution.
How to Improve Images Resolution
1) Cropping: Enhance focus and composition
Cropping can remove unwanted or distracting areas, improve the composition, or help emphasize
a focal point.
N.B: If you plan on doing significant cropping, try to start with a large image as possible. Because
the more you crop, the more you reduce your image quality and resolution.
When cropping, it is adviced to follow what’s known as the rule of thirds. This technique imagines
that your photo is divided into thirds, both vertically and horizontally, with four lines (two vertical,
two horizontal).
The four points where those lines would intersect form guidelines to place your focal point, or the
most important area of your image.
2) Blurring: Enhance background images
It is used for smoothing or reducing noise in images and uncluttered background.
While it is intentionally applied in some cases, it can also occur as a result of image compression or
other processing techniques, potentially affecting the clarity and accuracy of computer vision tasks.
Note: With some light to moderate blurring, you can retain recognizable shapes or scenes in your
background photos.
3) Saturation: Enhance or reduce color intensity
Saturation has to do with color intensity, so more saturated colors are bolder and brighter (closer
to their purest form) while less saturated colors are more faded (closer to gray). Complete
desaturation leaves you with a black-and-white photo
Note: While any photo editing technique can be overdone, too much saturation can look
particularly strange and unnatural. So, unless you’re after a particular effect, be careful to go easy
on the saturation, or else you’ll end up with an image that has an almost glowing, neon look.
4) Contrast: Enhance highlights and shadows
Increasing contrast is a good way to make your image pop (wow) and add a little drama.
Upping the contrast produces lighter lights, darker darks, and a wider range of tones in between—
making your image look just a little better than what you’d see in real life.
On the other hand, reducing contrast can give an image a more flat, even tone.
As with saturation, too much contrast is usually not a good thing. Highlights can get blown out
(too bright) and shadows can get too dark, which means you lose detail and dimension in those
areas.
5) Brightness: Enhance overall lighting
The brightness will make everything brighter (or darker). This should be done incrementally and
with attention to not creating areas that are overly bright, and you can often improve and balance
your results by adjusting the contrast at the same time.
6) Filters: Enhance and correct photos
Thanks to Instagram and other apps, filters have become a popular photo editing option. They can
be used to add special or artistic effects to your images, but they can also serve as a shortcut to
correct issues in your image.
However, most images shouldn’t need filters. Try to only apply one if you’re trying to achieve a
specific effect.
7) Arrangement: Enhance your layout with grids
A clean and organized layout is an asset to any design project. If you’re not sure where to start,
aligning all your design elements to a grid is always a safe bet. Grids are also a nice way to
showcase multiple images
8) Frames: Enhance image shape and style
Like actual picture frames, you hang on a wall, framing images in design is traditionally used to
draw attention to the image. Frames can be simple or decorative, a single line or an illustrated
design, colored or not, depending on the style and mood of your project.
9) Layering: Enhance images with screens or overlays
Screens (also called overlays) are a common approach. They are transparent blocks of color that
sit on top of your image. Adjusting the opacity of the screen determines how well your image will
show through.
10) Text: Enhance images with typography on top
Images and text are two foundations of graphic design (opens in a new tab or window). Combine
them, and they’re a powerhouse of visual communication. So, try adding relevant information to
an image by placing text on top (or picking an image that complements the subject of your text).
11) Auto Enhance: Automatically correct and enhance photos
Save time and effort with the Auto Enhance effect. With a single tap, easily adjust the
enhancement level. From correcting a dark image and making a picture clearer to fixing a photo’s
brightness and adjusting to your desired color aesthetic, the Auto Enhance effect lets you make
these changes quickly.
12) Photo Effects: Magically enhance photos
2) SOUND
Sound is a pressure wave which is created by a vibrating object.
Sound is created when something vibrates and sends waves of energy (vibration) into our ears.
Audible noise (sound) is generated by physically vibrating material. The vibration produces
pressure wave in the air, the pressure wave travel through the air, and ultimately cause our
eardrums to vibrate. The vibration of our ear drums is converted into electrical pulses sent to the
brain, which perceives the sound.
The five main characteristics of sound waves include wavelength, amplitude, frequency, time
period and velocity.
• Wavelength: The most important characteristic of sound waves may be the wavelength.
Sound consists of a longitudinal wave that includes compressions and rarefactions as they
travel through a given medium. The distance that one wave travels before it repeats itself
is the wavelength. It is the combined length of a compression and the adjacent rarefaction,
or the distance between the centers of two consecutive rarefactions or compressions.
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Amplitude: The amplitude is the size of a given wave. Think of it as sort of like the wave’s
height as opposed to its length. The amplitude is more accurately defined as the maximum
displacement of the particles the sound wave disturbs as it passes through a medium.
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Frequency: The frequency of sound refers to the number of sound waves a sound produces
per second. A low-frequency sound has fewer waves, while a high-frequency sound has
more. Sound frequency is measured in hertz (HZ) and is not dependent upon the medium
the sound is passing through.
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Time Period – The time period is almost the opposite of the frequency. It is the time
required to produce a single complete wave, or cycle. Each vibration of the vibrating body
producing the sound is equal to a wave.
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Velocity – finally, the velocity of the wave, sometimes referred to as the speed, is the
amount of distance in meters per second that a wave travels in one second.
DIGITALISATION OF SOUND
Note: If we want to use a digital version of sound wave, we must form digitized representations
of audio information.
Digitization is the process of representing various types of information in a form that can be stored
and processed by a digital device. It is the combined operations of sampling and quantization, also
called analog-todigital (A/D) conversion.
Unlike analog storage media such as magnetic tape or vinyl records, computers store audio
information digitally as a series of zeroes and ones. In digital storage, the original waveform is
broken up into individual snapshots called samples. This process is typically known
as digitizing or sampling the audio, but it is sometimes called analog-to-digital conversion.
When you record from a microphone into a computer, for example, analog-to-digital converters
transform the analog signal into digital samples that computers can store and process.
Steps Of Digitization Of Sound.
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Sampling - Audio sampling is the process of transforming a musical source into a digital
file. Digital audio recording does this by taking samples of the audio source along the
soundwaves at regular intervals. The more samples you take - known as the ‘sample rate’
- the more closely the final digital file will resemble the original. A higher sample rate
tends to deliver a better-quality audio reproduction.
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Quantization - quantization is the studio-software process of transforming
performed musical notes, which may have some imprecision due to expressive
performance, to an underlying musical representation that eliminates the imprecision. The
process results in notes being set on beats and on exact fractions of beats
The purpose of quantization in music processing is to provide a more beat-accurate timing
of sounds
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Encoding - Encoding is the process of changing digital audio from one format to another.
There are two broad types of formats - uncompressed and compressed. Uncompressed
audio is mainly found in the PCM format of audio CDs. Generally, audio encoding means
going from uncompressed PCM, to some kind of compressed audio format.
Monophonic and Stereophonic Sound
Mono (monophonic) sound is single-channel audio where all the instruments are mixed into one
signal, intended to be heard as if emanating from one position.
Stereo (stereophonic) sound is achieved by using two audio channels feeding 2 separate speakers.
This creates a more three-dimensional sound, and better resembles how we hear things in the world
at large.
What is Stereo sound?
Stereo is sound recorded with two microphones and or played back through two channels (a left
and a right that are outputted to two (usually separate) speakers, and could be anything from laptop
speaker etc)
All our listening systems are configured in stereo; our phones, laptop speakers, headphones,
the sound in films, the sound in video games, the PA systems in clubs and festivals, and so on.
There two types of stereo Sound.
There is True Stereo and Pseudo Stereo.
True stereo is when a sound source like an instrument or dialogue is recorded with two
microphones.
Pseudo stereo or, simulated stereo is anything that plays through two channels but isn’t recorded
in true stereo. For example, if you record a guitar with one microphone, the guitar will be in mono
but played back in stereo, because all audio playback systems play sound through two channels.
Stereo mixing allows for precise placement and separation of different elements in the mix. By
panning (separating) instruments across the stereo field, you make it easier for listeners to
distinguish individual elements within the music.
Mixing in stereo opens up a world of creative possibilities. Moving sounds across the stereo field,
or sculpting stereo sounds can create unique sonic landscapes making your music more engaging
and dramatic.
What is Mono Sound?
Mono sound is any sound – in most cases, music, that is recorded and or played back
using one audio channel (all the instruments are mixed into one signal, intended to be heard as if
emanating from one position).
For example, one microphone recording a guitar is a mono recording, because you’re
using one channel (with one mic) to pick up the sound of the guitar.
Even if you record multiple instruments, using one microphone, it is still a mono recording because
everything is being captured and played back through one channel.
It doesn’t matter how many sounds or instruments there are in the recording. If it is all sent
through one channel, it is mono.
Mono sound remains most commonly used for voice recordings because of its advantages in
reducing background noise and capturing a voice in the clearest, most natural way possible.
ADVANTAGES AND DISADVANTAGES OF MONO VS STEREO
SOUND
PROS AND CONS OF MONO SOUND
Pros:
Clarity
And
Focus:
Mono sound offers a clear and focused listening experience, making it ideal for speech and singleinstrument recordings.
Compatibility:
Works well on all speakers and systems, ensuring consistent playback.
Simplicity
In
Mixing:
Mixing in mono is more straightforward, as it doesn’t involve balancing multiple channels in a
stereo field.
Cons:
Lack
Of
Depth:
Mono sound does not provide stereo sound’s spatial depth and immersive experience.
Limited
Creative
Options:
Offers fewer opportunities for creative sound placement and effects.
PROS AND CONS OF STEREO SOUND
Pros:
Immersive
Experience:
Stereo provides a more realistic and engaging listening experience, with sounds appearing to come
from different directions.
Creative
Flexibility:
Allows for innovative use of the sound space, enhancing the artistic expression in music.
Depth
And
Realism:
Adds depth and realism to recordings, making them feel more lifelike.
Cons:
Complexity:
Requires more careful mixing and mastering to maintain balance and prevent phase issues.
Inconsistency
Across
Playback
Systems:
Stereo sound can vary greatly depending on the listening environment and equipment.
Differences between Mono vs. Stereo sound
1) Cost
Mono sound is easy and inexpensive, whereas stereo sound is more expensive for recording and
reproduction.
2) Recording
Mono sound is easy to record, requiring only basic equipment while working on production,
whereas stereo sound requires technical knowledge and audio skills to record, apart from recording
equipment. The recording artist needs to know the relative position of the objects and events.
3) Usage
Mono sound is generally used for alert systems, radio talk shows, hearing aids, public address
systems, telephone, mobile communication, etc. In addition, movies, television, music players, FM
radio stations, podcasts, and other apps like Spotify, Gaana use stereo sound.
4) Playback
Mono has only one channel of playback while stereo has two channels of playback.
Note.
Even though there are many benefits and user experience advantages of stereo sound over the
mono sound. The importance of mono sound is not reduced. Some of the important vocals and
sounds are still recorded in mono sound.
Mono VS Stereo Sound: Which One is Better
There is no definitive answer about which one is better. It all depends on our own preferences and
situations. For example, if you have a home theater system in your house, then you may need to
use stereo sound to get a better experience with even more channels. The stereo sound is ideal for
watching a movie and if there are lots of music and environmental sounds, as it allows you to
immerse yourself in the story.
If you only wear one earbud at a time, you would better choose mono sound. Then you will hear
the entire song and all its parts.
When converting a signal to a sound, you only need to use only one channel. When you use
multiple channels to convert multiple signals to sounds, then it will produce stereo sound. Your
preference for mono or stereo sound is entirely subjective, as everyone, like sound, is unique!
SIZE OF A SOUND FILE
Music files for standard, everyday listeners are typically between 96 kbps and 160 kbps on
streaming platforms like Spotify. But the highest quality MP3 can be 256 kbps to 320 kbps, and
CDs are even better, at 1411 kbps. These sizes are for final products; in studios and editing rooms,
raw file sizes are much larger.
The five major that impact both audio quality and audio file size include:
1. Sample Rate: Measured in Hertz, this is a frequency that represents the number of
“snapshots” per second taken from a sound. For example, when you listen to a song, you’re
not hearing exactly what was recorded in a studio. Instead, the song is made up of snapshots
2.
3.
4.
5.
of the sound (the frame rate for video files). Faster frequencies are more detailed, but also
result in larger audio or music files.
Bitrate: How much sound data is recorded in each sample, and then transferred into audio.
Again, a higher bitrate means better audio quality – and a larger file size.
Compression: Lossless and lossy compression are the two types of audio compression,
and these impact audio file sizes the most. “Generally, you should go with lossless
compression when you want to store a nearly perfect copy of the source material and lossy
compression when the imperfect copy is good enough for day-to-day usage.” The less
compression used, the better playback you’ll get.
File Format: Audio files come in a variety of types, each of which provides different
performance specs that influence the file size. File formats include:
o AIFF/AIF – Audio Interchange File Format, used for storing sound data on Apple
PCs and devices
o RF64 – For multichannel sound in broadcasting and audio archiving
o W64 – Wave64, supported on Sony editing programs
o WAV – Waveform Audio File Format, for storing audio bitstream on PCs,
particularly Windows
o WMA – Windows Media Audio
Channels: Audio files are played through channels. The most common are mono (one) and
stereo (two), but the number of channels can grow to include all recorded waveforms in an
audio file. For instance, MP3 files are typically stereo, with a left and right channel. Each
channel adds more data to a file size, with mono typically being the smallest, stereo being
roughly twice as large, and so on.
3) VIDEOS
Definition:
Videos are an electronic form of capturing moving media for storage and retrieval purposes.
Similar to images, we obtain videos using image-acquisition devices such as video cameras,
smartphones, and camcorders. So, we can divide videos into two categories: analog and digital.
1) Analog Video
Analog video signals are in the form of waves (like a radio wave).
Initially, we videos are aquired as analog signals and stored in mediums such as magnetic
tapes. A sensitive plate captures a scene at an instance, and electrodes read line by line
from left to right. So, we call “frame” a single reading from top to bottom of a
photosensitive plate by an electrode. Consequently, a complete video consists of several
frames displayed sequentially at a standard speed.
2) Digital Video
Digital video signals are in the form of 1's and 0's (it's either on or it's off).
Digital video is capable of higher quality and, eventually, a much lower cost than earlier
analog technology.
The digitization of videos is basically the digitization of frames. After digitization, we
can visualize each frame as a separate image. Besides, the digitalization process converts
videos to a form directly readable by computers. Digital videos allow the manipulation of
several video parameters, such as the frame rate, depth, size, and resolution.
Initially, the semiconductor-based sensors record the frames that make up digital movies.
A frame structure is a matrix of elements holding pixel values. The number of rows and
columns indicates the frame size.
Characteristics of Videos
1) Frame Rate
The frame rate specifies the speed of the video. For example, the rate of 20
frames/second indicates reading and displaying 20 frames each second.
2) Color depth
Color depth defines how visually appealing the video looks. Bits per pixel indicate
the number of colors possibly a pixel can display. Note that the color depth can change
according to the devices used for capturing and displaying videos.
3) Compression Method
The compression method used and the number of pixels utilized to represent the frames
define the quality of the videos.
4) Aspect Ratio
Aspect ratio describes the proportional relationship between the width and height of
video screens and video picture elements. All popular video formats are rectangular,
and this can be described by a ratio between width and height.
5) Color Model
The color model uses the video color representation and maps encoded color values to
visible colors reproduced by the system.
6) Video Quality
Video quality can be measured with formal metrics like peak signal-to-noise
ratio (PSNR) or through subjective video quality assessment using expert observation.
Storage Meduims
Digitalizing videos enabled several mediums to store them.
Among the most commonly used storage mediums are tapes, floppy disks, compact
disks (CDs), digital versatile disks (DVDs), and universal serial bus (USB) drives.
Compairing Analog and Digital Videos
Analog
Digital
Signal
Analog signal is a continuous signal
which represents physical
measurements.
Digital signals are discrete time signals
generated by digital modulation.
Waves
Denoted by sine waves
Denoted by square waves
Representation
Uses continuous range of values to
represent information
Uses discrete or discontinuous values to
represent information
Example
Human voice in
electronic devices.
analog
Computers, CDs, DVDs, and other digital
electronic devices.
Technology
Analog
technology
waveforms as they are.
records
Samples analog waveforms into a limited set of
numbers and records them.
Data
transmissions
Subjected to deterioration by noise
during transmission and write/read
cycle.
Can be noise-immune without deterioration
during transmission and write/read cycle.
Response
Noise
to More likely to get affected reducing
accuracy
Less affected since noise response are analog in
nature
Flexibility
Analog hardware is not flexible.
Digital hardware is flexible in implementation.
Uses
Can be used in analog devices only.
Best suited for audio and video
transmission.
Best suited
electronics.
Applications
Thermometer
PCs, PDAs
Bandwidth
Analog signal processing can be
done in real time and consumes less
bandwidth.
There is no guarantee that digital signal
processing can be done in real time and
consumes more bandwidth to carry out the
same information.
Memory
Stored in the form of wave signal
Stored in the form of binary bit
Power
Analog
power
Digital instrument drawS only negligible power
Cost
Low cost and portable
instrument
air,
draws
large
for
Computing
and
Cost is high and not easily portable
digital
Analog
Digital
Impedance
Low
High order of 100 megaohm
Errors
Analog instruments usually have a
scale which is cramped at lower end
and give considerable observational
errors.
Digital instruments are free from observational
errors like parallax and approximation errors.
Video Formats
As a video typically consists of multiple images, it demands higher storage space. Due to the size
of a video, it’s difficult for us to retrieve it from the storage medium and share it. However, we
require space-efficient resources for real-time applications. For these reasons, we can use
many compression formats.
A video file occupies large memory spaces based on many factors, such as frame size and video
length. We can store videos in many file formats. Each of these formats employs a particular
compression method.
Some videos contain similar-looking frames. For example, videos captured with slow-moving
objects or cameras at a fixed position may have many identical adjacent frames. Thus each video
format or compression standards use efficient techniques to handle these identical frames.
•
•
•
•
•
•
Examples of Video formats are: MOV
MP4
AVI
WMF
FLV
WebM
Pros and cons of Video
Pros
1) Video content is calls attention and has high engagement
2) Video content increases conversion rates
3) Video is the powerhouse for multimedia
4) Video content is perfectly suitable for mobile devices
5) Video is the engine of social media
Cons
1) Video content can be expensive
2) Producing a video takes a lot of time
3) Video content might not suit all types of audience
4) It’s hard to update videos or keep them unfading
Video Compression
A video codec is an integral part of video processing. It encompasses an algorithm or software that
executes two primary tasks – compression and decompression of video files.
The compression phase occurs before a video file is transmitted or stored. During compression,
the codec minimally reduces the size of the video file, preserved in a digital format. This
compression is vital to make the data easier to store or transmit over the internet. The smaller the
file size, the less bandwidth is needed for data transfer.
Decompression, on the other hand, happens at the receiving end. The compressed video data is
expanded back into its original form, enabling regular playback. The decoding happens on your
device when you play a video on a media player or streaming service. The codec translates the
compressed data into an uncompressed video, allowing you to view it.