Re: Calibrating Buffer Size and Count

On Fri, 2010-05-28 at 13:29 -0700, Chris Robinson wrote: 
> A "frame size", in this case, is the size of a single sample multiplied by the 
> channel count (ie. channels * bits / 8; which would be 4 for 16-bit stereo, or 
> 1 for 8-bit mono, for example). A "buffer size" would be the size of a given 
> buffer (typically in bytes, but sometimes it may be measured in frames or even 
> time).
> 
> So, for instance, you would generate 4 to 8 buffers, and fill them each with 
> frequency/4*channels*bits/8 bytes (where frequency, channels, and bits are 
> taken from the stream data format that's given to OpenAL):

The 4 in the divisor, is that the number of buffers one chose to
generate?

How do I determine the number of buffers to use for a stream? Do you
reckon to just hardcode it at, say, 8, and instead leave the size of the
buffers themselves as the parameter to fiddle with?

> int framesize = stream->channels * stream->bits / 8;
> BytesPerBuffer = stream->Freq / 4 * framesize;

The 4 again in the divisor is the number of buffers chosen for the
stream?

> When queued onto a source, the buffers should give a total play time of one to 
> two seconds before it all runs out, and approximately 1/4th of a second 
> between each buffer.

Very helpful Chris. I've made a note of that in my notes.

PS If you remember, please cc me so I get it faster than the batch mode
dispatches.

-- 
Kip Warner -- Software Engineer
OpenPGP encrypted/signed mail preferred
http://www.thevertigo.com

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