Re: Different input buffer and output buffer sizes in IOProc?
Re: Different input buffer and output buffer sizes in IOProc?
- Subject: Re: Different input buffer and output buffer sizes in IOProc?
- From: Jeff Moore <email@hidden>
- Date: Tue, 26 May 2009 13:03:49 -0700
It certainly sounds like you should be writing a bug about this.
On May 26, 2009, at 5:35 AM, Jesper Papmehl-Dufay wrote:
I have finally gotten hold of a M-Audio FW410, and I can reproduce
the problem easily by changing the sample rate of the device a few
times while my app is running.
If I look at the inInputData AudioBufferList that I get in my
IOProc, it looks like this:
mNumberBuffers = 1
mBuffers[0] =
mNumberChannels = 2
mDataByteSize = 4096
mData = some address
and the outOutputData AudioBufferList looks like this:
mNumberBuffers = 1
mBuffers[0] =
mNumberChannels = 10
mDataByteSize = 16384
mData = some address
When our code calculates the input buffer size in frames, it gets
4096 / (4 * 2) = 512
and the output buffer size in frames becomes 16384 / (4 * 10) = 409,6
(If outOutputData-> mBuffers[0].mNumberChannels would have been 8,
the output buffer size would be 512 frames and all would be well.)
Are we doing something wrong when calculating the buffer sizes? I'll
try to see if I can notice the problem in HALLab, but the problem
seems to exist for only a single IOProc call and then fix itself, so
I'm not sure how to reproduce it in HALLab.
--
Jeff Moore
Core Audio
Apple
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