Recording in CoreAudio driver seems to get ahead of our audio position?
Recording in CoreAudio driver seems to get ahead of our audio position?
- Subject: Recording in CoreAudio driver seems to get ahead of our audio position?
- From: Paul R Potts <email@hidden>
- Date: Wed, 13 Aug 2003 18:12:27 -0400
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
---
"Cats to become a rabbit should gather immediately now here."
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