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

21naown at gmail.com 21naown at gmail.com
Tue Nov 7 14:29:42 UTC 2017

Le 07/11/2017 à 12:31, Tanu Kaskinen a écrit :
> On Tue, 2017-11-07 at 00:30 +0100, 21naown at gmail.com wrote:
>> 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.
> I'm still a bit confused. "Other modules that maintain their own
> buffers may also have underrun or overrun situations" referred to
> PulseAudio modules, so that sentence had nothing to do with
> Jack/QJackCtl. Jack and QJackCtl are not PulseAudio modules. Jack can
> have underruns, which you won't see in PulseAudio logs. QJackCtl can't
> have underruns, because it's not streaming any audio, but QJackCtl can
> be used to show the count of underruns in Jack.
> If module-jack-sink is too slow to provide audio to Jack, that will
> show up as an underrun in Jack.

I did not really take into account the word “modules” when I read your 
sentence, sorry. But Jack can have underruns, at least I understood this 
correctly. And yes, QjackCtl is only a GUI for Jack, I stop associating 
them now.

>>>> 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 listed all problems that I could think of. I have 76% confidence that
> there can't be any other problems.
> I gave some bad advice, though:
>> "Actual underrun of 'application name'" will be logged when a playback
>> application fails to provide data to PulseAudio fast enough.
> That message will show up in the log only with the alsa sink. With the
> jack sink look for this message instead: "Implicit underrun of
> 'application name'".

If you cannot be 100% sure, is any problem replaced by a 0dB sound? If 
so, then I can check for a possible problem with Audacity and 
Sample Data Export. For example, if an underrun or a rewind occurs, is 
it replaced by 0dB by PulseAudio? Or it is a random value?

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