[alsa-devel] Audio artefacts but no xruns
mark at xwax.org
Sun Feb 2 13:04:00 CET 2014
I have several applications for realtime processing of audio in/out, using
small buffer sizes.
I often find that I can get audible time-based distoritions, yet no xrun
is reported, and the application is unaware.
This problem is something I have, for a long time, taken for granted with
ALSA. But it doesn't seem right and I would like to understand what's
going on here.
I am testing using different USB audio devices; snd-usb-audio and
snd-usb-caiaq. Often using plughw or hw.
Is this some fundamental limitation of USB, that it is unaware of problems
nearer to the hardware?
Or is this some bug where it's worth me narrowing down a specific test
case and trying to fix it?
Or some limitation of the use of intermediate processing like plughw?
The effects range from occasional subtle clicks through ringing or
noticable gaps in the audio, on record or playback.
At very least I would like to guarantee a notification in userland that
the integrity of the recording or playback is affected.
This is particularly prevalent on, eg. Raspberry Pi. My other tests are on
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