Game Development Reference
In-Depth Information
Chapter 6: Sound
1
.
Source sounds are the actual audio files created by a sound designer.
These are usually WAV files for sound effects and some sort of com-
pressed format for longer tracks. The metadata describes how and in what
context the source sound files should be played.
2
.
Switchable sound cues allow you to have different sets of sounds that play
in different circumstances. For example, footsteps sound differently de-
pending on the surface the character is walking on. With a switch, it
would be possible to switch between different footstep source sounds, de-
pending on the surface.
3
.
The listener is a virtual microphone that picks up all the sound that plays
in the world, whereas the emitter is the object that actually emits the
sound. In a first-person shooter (FPS), the listener might be at the camera,
while an emitter might be tied to every non-player character (NPC), as
well as other objects that may give off sound (such as a fireplace).
4
.
For a third-person game, both the position and orientation of the listener
are very important. The orientation should always be camera relative, not
player relative. If it's player relative, you could have a scenario where an
explosion that occurs on the right part of the screen comes out of the left
speaker, which is not desirable. The position of the listener is often placed
somewhere between the camera and the player position.
5
.
The decibel scale is a logarithmic scale. Going from 0 to -3 dB cuts the
volume of the sound roughly in half.
6
.
Digital signal processing involves taking a signal and transforming it in
some way. For audio, this is often used to alter a sound on playback. One
example is reverb, which creates an echo. Another example would be a
pitch shift, which increases or decreases the pitch of the sound. Lastly, a
compressor would normalize the volume levels by increasing the volume
of quieter sounds and decreasing the volume of louder sounds.
7
.
Oftentimes, a DSP effect such as a reverb only needs to affect part of the
level. Therefore, it is valuable to be able to mark which regions within the
level are affected by DSP.
8
.
Using a convex polygon to mark DSP might not work if the level has
some parts that are above or below other parts. For example, if a field has
