[pulseaudio-discuss] VLC + pulseaudio issues

[Rémi Denis-Courmont]

   Hello,

On Thu, 24 May 2012 14:08:12 -0400, Drew <drew.hope+pulseaudio at gmail.com>
wrote:
> I've been trying to figure out a problem I'm having with continuous
> dopplering of VLC when using pulseaudio for sound.  There is no
> dopplering with use of pure ALSA output.  I'd greatly appreciate any
> assistance as I've been unable to resolve this on my own after
> extensive google digging.

The log just shows that the latency estimation that PulseAudio provides to
VLC are unstable, showing a steep increase at nominal playback speed. VLC
tries to upsample (or rather asks PulseAudio to do so) so that audio can
keep up with the media clock, and in particular stay in sync with the video
signal, if any.

If it keeps on happening all the time, something is clearly broken. It
could be the audio hardware, the computer clock, the audio driver,
PulseAudio or VLC. Being unable to reproduce your problem, I would not
hazard a guess.

There are however a few things you can try:
- Configure PulseAudio to use the same sample rate as VLC does with the
"pure" ALSA output. If that works, the problem is probably with the audio
hardware or the audio driver.
- Try with all power management *disabled* and no other active
application, to rule out scheduling problems.
- Check that your computer clock is running properly, with reasonable
precision.
- Try with other file formats and codecs to rule out a VLC timestamping
bug or corrupt input file.

-- 
Rémi Denis-Courmont
Sent from my collocated server