[alsa-devel] [PATCH] alsa-lib: snd_pcm_delay and friends do not account for a write being currently in progress

[Clemens Ladisch]

VDR User wrote:
> I've been getting "pcm_hw.c: snd_pcm_hw_delay() SNDRV_PCM_IOCTL_DELAY
> failed." in my xine log

The actual error (code) is missing.

> and after some talks with one of the devs, he suggested that alsa was
> not getting data fast enough in some cases (iirc).

That would be an underrun.  This has nothing to do with the
interpretation of snd_pcm_delay's return value; this function just
appears in the log because it happend to be the first one that detected
this error condition.  An underrung cannot be prevented by any change
in alsa-lib; xine needs to use a larger buffer, or the scheduling needs
to be improved so that some other thread or program doesn't prevent xine
from being executed.


Regards,
Clemens