[pulseaudio-discuss] How to check visually for XRUNs/drop-out/interruptions and similar in PulseAudio?

21naown at gmail.com 21naown at gmail.com
Mon Nov 6 23:30:56 UTC 2017

Le 06/11/2017 à 11:00, Tanu Kaskinen a écrit :
> On Sun, 2017-11-05 at 19:23 +0100, 21naown at gmail.com wrote:
>> Le 05/11/2017 à 10:54, Tanu Kaskinen a écrit :
>>> The alsa sink will log "Underrun!" if PulseAudio doesn't write fast
>>> enough to alsa, but if you're only using jack as the output in
>>> PulseAudio, then that's irrelevant.
>>> Other modules that maintain their own buffers may also have underrun or
>>> overrun situations. I don't have a comprehensive list of them. I know
>>> module-loopback logs "Could not peek into queue" when it has an
>>> underrun in its buffer.
>> PulseAudio may have an overrun/underrun problem like jack/QjackCtl may
>> also be concerned, right?
> Sorry, I don't understand this sentence.

I would just like to be sure jack/QjackCtl may have overrun/underrun 
problems, but forget that since you have already well answered to this 
question with “Other modules that maintain their own buffers may also 
have underrun or overrun situations”. Sorry for this.

> Resampling can't be disabled. If a stream uses different sample rate
> than the sink where it plays to, then PulseAudio has to do resampling,
> i.e. converting audio from one sample rate to another.
> Remixing means adapting between different channel configurations when
> the stream channels don't match with the sink channels. If remixing is
> disabled, then channels that exist on the stream but not on the sink
> are dropped, and channels that exist on the sink but not on the stream
> get silence.

I compared resampling to remixing… Again sorry.

>> Are there other things similar to a drop-out in PulseAudio (if its
>> resampling is disabled)?
> I already answered this question in my last mail as well as I can.

Does your sentence mean “There are no other problems which may modify 
your sound with your configuration on the side of PulseAudio”? (= you 
are sure there are no other problems)
I would just like to be sure that with the following configuration, I 
may only get underrun or rewind problems, because I can easily identify 
them in the log thanks to you. I simply want the sound of the source 
file to exactly match the sound I will hear/record (by jack/QjackCtl). 
If it is not the case because of a problem, I need to know it. I prefer 
to ask you because if your answers may avoid me from manually checking 
each entry of the log with the level “debug” (at least 1830 lines since 
the boot) to know if the sound has been modified due to a problem, it 
will help me a lot.
Assuming the audio source has the same following configuration, here is 
the configuration in “/etc/pulse/daemon.conf” (I show only the values I 

enable-remixing = no
enable-lfe-remixing = no

default-sample-format = float32le
default-sample-rate = 48000
alternate-sample-rate = 48000
default-sample-channels = 2
default-channel-map = front-left,front-right

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