Rob Nertney wrote:
I have successfully built a sound capture card that runs at a given rate off its own clock. I receive the stream and do some post-processing on it, and I want to present this modified data to the user as a capture pcm.
Then you probably want to create an external filter plugin: http://www.alsa-project.org/alsa-doc/alsa-lib/pcm_external_plugins.html
I initially thought that snd_aloop would be the best idea, as I can pipe my post-processed data directly into it. However, the driver is apparently calculating exact timing of what "should" be the rate based off of CPU ticks/jiffies and the requested period/sample rate/etc in the requested output stream.
Yes; the timing is not synchronized with any other sound card.
Regards, Clemens