[pulseaudio-discuss] null-sink rewinds causing stutter

[Daniel]

The problem nearly goes away, as long as pavucontrol is running... skipping
then works without hiccups and fading volume only causes a little bit of
rasping.

Sadly this causes the cpu load to raise over a level that I can accept on
this old netbook for a longer time. So this is no workaround for me.

Does this give anybody a clue to the cause? This sounds utterly ridiculous
to me....

Thanks for any help


2013/11/22 Daniel <windseeker at gmx.de>

> Hello Tanu,
>
> that's a nice catch! Indeed this is exactly what I have, just that volume
> changing triggers it way more noticably, because of the high frequency of
> triggers. And indeed it's also there when recording from an
> alsa-sink.monitor. I just thought this would be fine, because the audio out
> of the speakers is fine, but the recorded result is broken just as with a
> null-sink.
>
> I could reproduce that on 3 different machines, so it's reproducable
> anytime. Record any audio from any sink.monitor and change volume of the
> stream input or the sink itself and watch it happen.
>
> I am able to grab source code out of a VCS, I can patch and I can compile,
> I can package and I can test and analyze. The only thing I cannot do, is
> writing code :(
>
> Anyway: Thank you very much.
>
> Best,
> Daniel
>
>
> 2013/11/22 Tanu Kaskinen <tanu.kaskinen at linux.intel.com>
>
>> 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
>>
>> --
>> Tanu
>>
>>
>
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