[alsa-devel] ALSA and Ubuntu

Andreas Falkenhahn andreas at airsoftsoftwair.de
Thu May 13 20:39:42 CEST 2010


I just downloaded the latest Ubuntu Live CD (10.04) to try my app on it.
It is a plain X11 app using ALSA for sound output. I developed it on
openSUSE 11.2 and thought to give it a try on Ubuntu... that was a
mistake, because on Ubuntu, there seem to be lots of errors with ALSA.
Here are some observations:

1) snd_pcm_status_get_tstamp() always returns 0 for sec/usec.

2) snd_pcm_status_get_state() always returns SND_PCM_STATE_RUNNING, even
when the PCM stream has long reached a buffer underrun.

3) snd_pcm_delay()'s return value doesn't fall below ~7000 samples or so.
Even when the buffer has underrun, the return value is not 0 but about
~7000 samples. This makes it nearly impossible to detect when I should
start writing new samples to the buffer...

Could someone enlighten me what's going on there? Is this a known issue
with Ubuntu? I'm not using any weird addons or stuff. It's really just the
latest Ubuntu live CD. As I said, on openSUSE everything is working just
fine. But on Ubuntu, hell is really breaking loose here...

Thanks for help,


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