[alsa-devel] [PATCH] Alsa-plugins: Pulse: Fix snd_pcm_avail returning 0 in some cases

[Takashi Iwai]

At Tue, 26 Apr 2011 10:01:23 +0200,
David Henningsson wrote:
> 
> On 2011-04-22 01:25, Raymond Yau wrote:
> > 2011/4/21 David Henningsson<david.henningsson at canonical.com>
> >
> >> Due to a round-off error, snd_pcm_avail could in some cases
> >> return 0 even though more data could be written to the stream.
> >>
> >> This was discovered by Maarten Lankhorst [1], and there is also a test
> >> program available that triggers this error [2].
> >>
> >> [1]
> >> https://tango.0pointer.de/pipermail/pulseaudio-discuss/2011-April/009935.html
> >>
> >> [2]
> >> https://tango.0pointer.de/pipermail/pulseaudio-discuss/attachments/20110420/3c852d6e/attachment.c
> >>
> >
> > if the test program can force under-run occur with "hw" device and "pulse"
> > device with his patch in
> > https://tango.0pointer.de/pipermail/pulseaudio-discuss/2011-April/009918.html
> >
> > Is it normal that underrun does not occur with the test program and your
> > patch
> 
> Yes; underruns are not reported to the application due to the risk of 
> the underrun being obsolete at that time. As for Maarten's patch in the 
> post you refer to,
> 
> 1) if underruns are being reported (this is configurable), it might be a 
> good idea to call "pulse_start".
> 
> 2) it changes underruns to being reported by default, which is what I'm 
> opposed to.

Applied now.  Thanks.


Takashi