[pulseaudio-discuss] How to debug intermittent audio skips?

[Charles Lindsay]

This is what showed up in the debug log as it skipped:

( 684.030|   5.000) I: [alsa-sink] alsa-sink.c: Underrun!
( 684.030|   0.000) I: [alsa-sink] alsa-sink.c: Increasing minimal latency
to 26.00 ms
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 26.00ms
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=60952
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15944
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 26.00ms
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=60952
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15944
( 684.031|   0.000) D: [alsa-sink] protocol-native.c: Underrun on 'ALSA
Playback', 0 bytes in queue.
( 684.036|   0.004) D: [alsa-sink] protocol-native.c: Requesting rewind due
to end of underrun.
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: Requested to rewind 10940
bytes.
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: Limited to 3320 bytes.
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: before: 830
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: after: 830
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: Rewound 3320 bytes.
( 684.036|   0.000) D: [alsa-sink] sink.c: Processing rewind...
( 684.036|   0.000) D: [alsa-sink] sink.c: latency = 1337
( 684.036|   0.000) D: [alsa-sink] sink-input.c: Have to rewind 3320 bytes
on render memblockq.
( 684.036|   0.000) D: [alsa-sink] source.c: Processing rewind...
( 696.234|  12.197) I: [alsa-sink] alsa-sink.c: Underrun!
( 696.234|   0.000) I: [alsa-sink] alsa-sink.c: Increasing wakeup watermark
to 15.99 ms
( 702.033|   5.799) I: [alsa-sink] alsa-sink.c: Underrun!
( 702.033|   0.000) I: [alsa-sink] alsa-sink.c: Increasing minimal latency
to 36.00 ms
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 36.00ms
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=59188
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15680
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 36.00ms
( 702.034|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=59188
( 702.034|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15680
( 702.034|   0.000) D: [alsa-sink] protocol-native.c: Underrun on 'ALSA
Playback', 0 bytes in queue.

...and it goes on.

The "Underrun!" messages happened a few times before, but it didn't skip.
The "rewind" messages sound like the ominous part to me.

Any idea what's wrong with my setup?  What can I do from here?  Thanks!


Charles


On Thu, May 3, 2012 at 10:44 PM, Tanu Kaskinen <tanu.kaskinen at digia.com>wrote:

> On Thu, 2012-05-03 at 22:32 -0700, Charles Lindsay wrote:
> > Hey guys, I was hoping I could get some help debugging a problem I'm
> > having with PulseAudio.
> >
> > If I'm playing music via any source (Exaile, Totem, Flash in Firefox
> > or Chromium, VLC, etc.) every few minutes the audio will skip once or
> > twice.  top doesn't show any process eating CPU any more when it
> > happens.  dmesg doesn't show anything.  Nothing else seems to be
> > affected.  It doesn't seem to happen regularly.
> >
> > I just installed Ubuntu 12.04 from scratch (with pulseaudio
> > 1:1.1-0ubuntu15), but the same thing happened in 10.04 on the same
> > hardware.  Uninstalling the PulseAudio packages and going back to ALSA
> > gives me no issues whatsoever, which is how I know the issue is with
> > PulseAudio.  I'm using my onboard audio device:
> >
> > $ lspci | grep Audio
> > 00:14.2 Audio device: Advanced Micro Devices [AMD] nee ATI SBx00
> > Azalia (Intel HDA)
> >
> > Any clues what's going on?  Is there any PulseAudio log I can look at?
> > Is there any way to debug the issue at all?  Should I just file a bug?
> > I'd like to use PulseAudio since it's so integrated into Ubuntu these
> > days, but it's annoying enough that if the issue continues I can't.
> > Thanks!
>
> I'd start from checking if there's anything printed to Pulseaudio log
> when the skips happen. Open a terminal, then enter these commands:
>
> echo autospawn = no >> ~/.pulse/client.conf
> killall pulseaudio
> LANG=C pulseaudio -vvvv --log-time
>
> Then start playing something. Then press enter in the pulseaudio
> terminal window a couple of times to get some emtpy lines in the log.
> Then wait for the problem to happen. When it happens, check the terminal
> window - what has been printed to the log after the empty lines? If you
> can reproduce this by doing absolutely nothing, then you can stare at
> the terminal window all the time to make sure that whatever is printed
> to the log, it is actually printed at the same time when the skips
> happen.
>
> --
> Tanu
>
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> pulseaudio-discuss at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
>
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