Re: Calibrating Buffer Size and Count

On Sunday, May 30, 2010 12:39:40 pm Kip Warner wrote:
> For audio effects, probably 48 KHz files will be used. For music, they
> may end up being 96 KHz / 24-bit.

FWIW, I'd imagine most games use 44.1khz, or possibly 48khz, for music, and 
either 22khz or 44.1khz for sound effects (16-bit for each). There's nothing 
really wrong with using more, though, as long as you're okay with the 
increased memory use.

Also be aware that OpenAL doesn't support 24-bit samples. They would need to 
be converted on load to 32-bit float for use with the AL_EXT_FLOAT32 
extension, or else convert to 16-bit.

> Do you recommend having the sole
> configurable aspect being the total length of the entire buffer queue
> for a source? That way a user can select 500 ms, 1s, 2s, etc. for their
> machine and it can automatically calculate the size of each buffer
> required, given the number of hard coded buffers, bit rate, frequency,
> channels, etc..

I'd recommend that any hard-coded buffer size be specified using sample 
frames, so it can increase with higher-resolution samples (eg. multiply by 2 
for 16-bit mono, and 8 for 32-bit float stereo). But beyond that, increasing 
the number of buffers for higher sample rates should be fine. eg:

BufferBytes = 16384 * (channels*bitspersample/8);
BufferCount = max(4*samplerate/44100, 2);

So that rates above 44.1khz will use more buffers to keep from running out too 
fast (and rates below will use less, but you'll need at least two regardless).

> Very helpful and thank you. You're very knowledgeable and this is
> helping greatly as I finish up the audio component of the engine design
> for my game (https://www.avaneya.com). Actually, when the design is
> done, it would be really helpful if you were able to take a moment and
> look at just the AudioManager's UML.

You're welcome. And I can take a look at it when it's done, sure. :)
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