Game Development Reference
In-Depth Information
generally shifts automatically between high and low quality, or in
many cases, just shoots for the lowest common speed available.
These dynamic shifts in speed and performance are something
you have to be savvy to. You must be prepared to work with the
development team on the overall loading and unloading of sound
assets, so that your sounds don't disrupt gameplay, yet still get the
attention they deserve.
Tips for Working on Mobile Game
Platforms
Consider what corners you can cut to reduce i le size. For example, do
your sound ef ects really have to be at 16 bit, 44.1KHz? Sometimes a
more limited frequency response will have no discernable ef ect on end
sound quality, due to the type of sounds (simple, short duration impact
sounds, for example) or the frequency response of the speaker it is being
played on. In a case like this, downsampling to 16-bit, 22KHz might save
you some space and maybe even increase performance! It's okay to have
your voice-over, SFX and music at dif erent sample rates, as long as the
engine and operating system allow it.
Audio compression for ambient backgrounds is a given! Remember,
2 minutes of stereo audio uses over 20MB, which is a ton for a mobile
game. By editing your ambient loops as ei ciently as possible, and using
a compression scheme like MP3 or Ogg Vorbis, you can save valuable
space and keep the audio quality as high as possible. You might also
reconsider using MP3 at high bit rates. It sounds great, but not all
portable devices will support it. The same is true for variable bit rate
i les (these are i les where the encoding rate can vary depending on the
complexity of the music). To be safe, it's generally best to use constant
and common bit rates.
If typical 10:1 compression via MP3 or Ogg isn't available at 128Kbps,
try IMA ADPCM, an early audio-compression codec that works on a 4:1
compression ratio that cuts i le size down to 25 percent of the original
size. Though the result will be lossy compared to the original, it's a good
compromise that preserves more of the original sound.
Don't assume that MP3 i les will loop seamlessly. Did you know that MP3
encoding can wreak havoc on perfectly good looping i les? It's sad but
true . . . this is because the MP3 format allocates i le space in blocks or
frames. When there are not enough samples to i ll an entire frame, blank
space is inserted to i ll the void. Engines like Flash and Unity deal with
