[pulseaudio-discuss] null-sink rewinds causing stutter

Tanu Kaskinen tanu.kaskinen at linux.intel.com
Fri Nov 22 08:53:14 PST 2013

On Fri, 2013-11-22 at 13:56 +0100, Daniel wrote:
> Dear list,
> I ask you for some assistance with null-sink and skipping/stutter.
> On client connect/disconnect and volume changes and many more things,
> pulseaudio does a buffer rewind to let the changes take effect immediately.
> So far,s o good, on all my soundcards this works like a charm.
> Now I have some audio stream setup where I play audio to a null-sink and
> record it from null.monitor. This works really great, until some action
> like pause/play, volume change, or connecting another audio client is
> causing a rewind. Then the recorded audio hangs for approx 200ms or even
> more. On soft volume changes, there are many many rewinds done, and so I
> have many of these skips.
> The skipping audio is actually hanging, it does not drop any data. There is
> just a silent break of about 200ms inserted into the stream.
> Of course it would be great to make rewinding on null sink just work as it
> does on alsa sinks, but in case this is inevitable, I would be fine with
> some possibility to disable rewinding. I know that all action then are
> delayed, but that would be okay for me as the stream is delayed about 8
> seconds anyway, until it reaches the receiver.

There's no reason why those glitches should be inevitable, so probably
module-null-sink or the rewind handling of monitor sources in general
has some bug. Now we just need someone to send a fix for the bug...

Not that this will help you much, but this bug might have the same root
cause: https://bugs.freedesktop.org/show_bug.cgi?id=68107


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