Re: Recording in CoreAudio driver seems to get ahead of our audio position?
Re: Recording in CoreAudio driver seems to get ahead of our audio position?
- Subject: Re: Recording in CoreAudio driver seems to get ahead of our audio position?
- From: Jeff Moore <email@hidden>
- Date: Wed, 13 Aug 2003 15:27:10 -0700
This most likely means that your time stamps are not accurate enough
and you have not calculated the appropriate safety offset.
On Wednesday, August 13, 2003, at 3:12 PM, Paul R Potts wrote:
We're testing recording in our CoreAudio device driver. Playback seems
to work well, but we get clicks and pops on recording. Close analysis
indicates that the audio HAL seems to be either very closely behind or
slightly ahead of the position of our DMA audio. At the point where we
wrap, and possibly elsewhere, we're getting old data because the HAL
copy is getting ahead of the fresh data the DMA is writing. It seems
to get ahead by about 30 samples.
We've tried changing SetInputSampleLatency() and SetSampleOffset()
with values from 30 to 1,000 but these two calls have no visible
effect on the position. Daisy correctly recognizes and displays these
numbers but the driver does not seem to change its behavior (we put in
logging the pointers when ConvertInputSamples is called; the logging
writes to a buffers shared with a user-space process so that we can
dump out the results).
What can we do to make the copy stay far enough away from our DMA
position?
Thanks,
Paul
---
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--
Jeff Moore
Core Audio
Apple
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