Sound / Audio / Music
How do we obtain sounds?
How do we obtain sounds?

We sample them!
Sampling:
– analog to digital
– continuous to discrete
Must be done carefully!
stereo
Problem:
Correct and
incorrect
sampling rates
(sampling
frequency; x
direction).
Problem:
Quantization (not enough bits in our
ADC; y direction).
Audio File Formats

Unity supported audio file formats



MP(EG)1/2/3, Ogg Vorbis, wav, and AIFF
mono or stereo
Torque supported audio file formats


.wav files & .ogg files (Ogg Vorbis)
mono or stereo
Audio File Formats

Compression (AKA CODECS) types:


Ex.



lossy vs. lossless
6.1M mp3 file converted to a 5.1M .ogg file
and a 33.9M .wav file
7.6M mp3 file converted to a 8.6M .ogg file
and a 83.2M .wav file
But game engines may pause while
decompressing large files.
Audio File Formats

Compressed




Compress sounds by choosing the compressed option from inside the
Editor. The audio data will be small, but will cost CPU cycles to decode at
play time. Depending on the target, Unity will encode the audio to either
Ogg Vorbis (Mac/PC/Consoles) or MP3 (Mobile platforms).
For the best sound quality supply the audio in an uncompressed format
such as WAV or AIFF (containing PCM data) and let Unity do the encoding.
If only targeting Mac/PC (standalones, webplayers) importing an Ogg
Vorbis file will not degrade the quality. But converting to mobile platforms
will force a re-encode to MP3 and cause a slight quality degradation.
Same goes for importing MP3, when only targeting mobile platforms.
Native

Use Native (WAV, AIFF) audio for short sound effects. The audio data will
be larger, but sounds won't need to be decoded at play time.
Audio File Editor: Audacity
(audacity.sourceforge.net)
Audacity: record, play, etc.
Audacity: select and cut
Audacity: after cut
Audacity: Fit-in-Window
Audacity: after Fit-in-Window
Audacity: add reverb effect to selection
Audacity: add reverb effect to selection
Add a cheesy wah wah effect to your
selection (but preview it first).
http://www.youtube.com/watch?v=Ovld0LDOBg0
http://www.youtube.com/watch?v=OEJh2FFUUoU
Audio in Unity
Audio Components




Audio
Audio
Audio
Audio







Clip
Listener
Source
Effects (PRO only)
Audio
Audio
Audio
Audio
Audio
Audio
Low Pass Filter
High Pass Filter
Echo Filter
Distortion Filter
Reverb Filter
Chorus Filter
Reverb Zones
(PRO only)
(PRO only)
(PRO only)
(PRO only)
(PRO only)
(PRO only)
Audio in Unity
Audio Components
The following slides were compiled from information
available from the excellent Unity reference manual
(http://unity3d.com/support/documentation/Compone
nts/index.html).
AUDIO CLIP
Audio in Unity
Audio Components: Audio Clip

Audio Clips are audio data used by Audio Sources.
Unity supports mono, stereo and multi (up to 8)
channels audio assets. Unity supports importing the
following audio file formats: .aif, .wav, .mp3, and
.ogg.
Audio in Unity
Audio Components: Audio Clip
Audio in Unity
Audio Components: Audio Clip





Audio Format
The specific format that will be used for the sound at runtime.
Native
Larger file size, higher quality. Best for very short sound effects.
Compressed
Smaller file size, lower/variable quality. Best for medium
length sound effects and music.
3D Sound If enabled, the sound will play back in 3D space. Both Mono and Stereo
sounds can be played in 3D.
Force to mono
If enabled, the audio clip will be down-mixed to a single
channel sound.
Audio in Unity
Audio Components: Audio Clip (cont’d.)





Load Type The way Unity load audio assets runtime.
Decompress on load Decompress sounds upon load. Use this for smaller
compressed sounds to avoid the performance overhead of decompressing on the fly.
Beware that a compressed sound will use ~10x more memory that when
decompressed, so don't use this for large files.
Compressed in memory
Keep sounds compressed in memory and
decompress while playing. This have a slight performance overhead (esp. for
Ogg/Vorbis compressed files) so only use this for bigger files.
Stream from disc
Stream audio data directly from disc. This uses a fraction of
the original sounds size of memory. Use this for your music or very long tracks.
Depending on the hardware, a general advice is to keep this down to 1-2
simultaneously streams.
Compression
Amount of Compression to be applied to a Compressed clip.
Statistics about file size can be seen beneath the slider. It is suggested to drag the
slider to a place that leaves the playback "good enough" but still at a small enough
size to meet your file size/distribution needs.
AUDIO LISTENER
Audio in Unity
Audio Components: Audio Listener



The Audio Listener acts as a microphone-like device.
It receives input from any given Audio Source in the
scene and plays sounds through the computer
speakers.
For most applications it makes the most sense to
attach the listener to the Main Camera.
If an audio listener is within the boundaries of a
Reverb Zone reverberation is applied to all audible
sounds in the scene. (PRO only) Furthermore, Audio
Effects can be applied to the listener and it will be
applied to all audible sounds in the scene.
AUDIO SOURCE
Audio in Unity
Audio Components: Audio Source

The Audio Source plays back an Audio Clip in the scene.
If the Audio Clip is a 3D clip, the source is played back
at a given position and will attenuate over distance. The
audio can be spread out between speakers (stereo to
7.1) (Spread) and morphed between 3D and 2D
(PanLevel). This can be controlled over distance with
falloff curves. Also, if the listener is within 1 or multiple
Reverb Zones, reverberations is applied to the source.
(PRO only) Individual filters can be applied to each
audio source for an even richer audio experience. See
Audio Effects for more details.
Audio in Unity
Audio Components: Audio Source
The Audio Source
gizmo in the Scene
View and its settings
in the inspector.
Audio in Unity
Audio Components: Audio Source
 Rolloff mode: How fast the sound fades. The
higher the value, the closer the Listener has
to be before hearing the sound.
Audio in Unity
Audio Components: Audio Source
 Rolloff mode types:
1.
2.
3.
Logarithmic rolloff: The sound is loud when you
are close to the audio source, but when you get
away from the object it decreases significantly fast.
Linear rolloff: The more far away from the audio
source you go, the less you can hear it.
Custom rolloff: The sound from the audio source
behaves accordingly to how you set the graph of
roll offs.
Audio in Unity
Audio Components: Audio Source
 Rolloff mode types:
1.
2.
3.
Logarithmic Rolloff
Linear Rolloff
Custom Rolloff
Audio in Unity
Audio Components: Audio Source

Distance Functions

There are several properties of the audio that can be modified
as a function of the distance between the audio source and the
audio listener.




Volume:
Amplitude(0.0 - 1.0) over distance.
Pan:
Left(-1.0) to Right(1.0) over distance.
Spread:
Angle (degrees 0.0 - 360.0) over distance.
Low-Pass (only if LowPassFilter is attached to the AudioSource):
Cutoff Frequency (22000.0-10.0) over distance.
Audio in Unity
Audio Components: Audio Source properties









Audio Clip
Reference to the sound clip file that will be played.
Mute
If enabled the sound will be playing but muted.
Bypass Effects
This Is to quickly "by-pass" filter effects applied to the audio source.
An easy way to turn all effects on/off.
Play On Awake
If enabled, the sound will start playing the moment the scene
launches. If disabled, you need to start it using the Play() command from scripting.
Loop
Enable this to make the Audio Clip loop when it reaches the end.
Priority
Determines the priority of this audio source among all the ones that coexist in the
scene. (Priority: 0 = most important. 256 = least important. Default = 128.). Use 0 for music
tracks to avoid it getting occasionally swapped out.
Volume
How loud the sound is at a distance of 1 world unit (1 meter) from the Audio
Listener.
Pitch
Amount of change in pitch due to slowdown/speed up of the Audio Clip. Value 1 is
normal playback speed.
3D Sound Settings
Settings that are applied to the audio source if the is a 3D Sound.
Audio in Unity
Audio Components: Audio Source properties
(cont’d.)








Pan Level
Sets how much the 3d engine has an effect on the audio source.
Spread
Sets the spread angle to 3d stereo or multichannel sound in speaker space.
Doppler LevelDetermines how much doppler effect will be applied to this audio source (if is set
to 0, then no effect is applied).
Min Distance Within the MinDistance, the sound will stay at loudest possible. Outside
MinDistance it will begin to attenuate. Increase the MinDistance of a sound to make it 'louder' in
a 3d world, and decrease it to make it 'quieter' in a 3d world.
Max Distance The distance where the sound stops attenuating at. Beyond this point it will stay at
the volume it would be at MaxDistance units from the listener and will not attenuate any more.
Rolloff Mode How fast the sound fades. The higher the value, the closer the Listener has to be
before hearing the sound.
2D Sound Settings
Settings that are applied to the audio source if the is a 3D Sound.
Pan 2D
Sets how much the engine has an effect on the audio source.
AUDIO EFFECTS
Audio in Unity
Audio Components

Audio Effects






Audio
Audio
Audio
Audio
Audio
Audio
Low Pass Filter
High Pass Filter
Echo Filter
Distortion Filter
Reverb Filter
Chorus Filter
(PRO only)
(PRO
(PRO
(PRO
(PRO
(PRO
(PRO
only)
only)
only)
only)
only)
only)
Audio in Unity
Audio Components

Audio Effects






Audio
Audio
Audio
Audio
Audio
Audio
Low Pass Filter
High Pass Filter
Echo Filter
Distortion Filter
Reverb Filter
Chorus Filter
(PRO only)
(PRO
(PRO
(PRO
(PRO
(PRO
(PRO
only)
only)
only)
only)
only)
only)
REVERB ZONES
Audio in Unity
Audio Components: Reverb Zones
 Reverb Zones take an Audio Clip and
distortionates it depending where the audio
listener is located inside the reverb zone.
 They are used when you want to gradually
change from a point where there is no
ambient effect to a place where there is one.
For example when you are entering a cavern.
Audio in Unity
Audio Components: Reverb Zones

The Audio Reverb Zone gizmo seen in the inspector:
Audio in Unity
Audio Components: Reverb Zones Properties



Min Distance - Represents the radius of the inner circle
in the gizmo, this determines the zone where there is a
gradually reverb effect and a full reverb zone.
Max Distance - Represents the radius of the outer circle
in the gizmo, this determines the zone where there is
no effect and where the reverb starts to get applied
gradually.
Reverb Preset - Determines the reverb effect that will
be used by the reverb zone.
Examples





Player sounds (footsteps, utterances)
Weapon sounds
Vehicle sounds
Environmental sounds
Interface sounds
Converting stereo to mono with
Audacity
(Many game engines require mono sources for 3D
sound, i.e. sound with volume based upon
listener distance.)
1.
Split stereo track.
2.
Make both tracks mono.
3.
Use the level control for each track, found on the
left of the track, to set to: "Gain: -6 dB". Then
when you quick mix, it is guaranteed to not clip.
4.
Select both tracks
5.
Project -> Quick Mix.
6.
Save mono audio as .wav or .ogg.
Sounds on the internet

The altavista.com search engine no
longer allows you to search for audio files
(and specific audio file formats).
Sound/audio example
Demo Audacity and “Good Times.”

file:///j://pub_html/csc343/slides/gt.aup


(actually an XML file)
Isolate the bass track.
1.
2.
lowpass filter
slow tempo but maintain pitch
Sound/audio exercise
Unity Sound exercise.