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

21naown at gmail.com 21naown at gmail.com
Sun Nov 12 15:07:47 UTC 2017

Le 09/11/2017 à 12:41, Tanu Kaskinen a écrit :
> On Wed, 2017-11-08 at 15:31 +0100, 21naown at gmail.com wrote:
>> Le 08/11/2017 à 12:43, Tanu Kaskinen a écrit :
>>> The issues with rewinds were about monitor sources and resampling. If I
>>> understood correctly, your source material is in 48000 Hz and Jack is
>>> configured with that rate too, so there's no need for resampling, and
>>> you haven't mentioned recording from a monitor source either, so there
>>> should be no reason to be concerned about rewinds. If rewinds happen,
>>> they shouldn't cause any glitches.
>>> But if you're curious, the monitor source bug causes short chunks of
>>> audio to be duplicated in the recording stream. I haven't seen concrete
>>> examples of what kind of glitches resamplers can have, but my intuition
>>> is that one sample in the audio stream might have a significant
>>> adjustment towards zero, and a few samples after that might have
>>> slightly wrong values.
>> I give you my audio chain more precisely:
>> Playing = Audio file (to simplify) → PulseAudio (→
>> pulseaudio-module-jack) → Jack → Audacity = Recording
>> “Audio file” means the audio source is in the computer, it is not taken
>> by a microphone for example (is this is what you said by “monitor
>> source”? Or you talk about the tab in pavucontrol “Recording → Audacity
>> → Monitor of SOMETHING”?).
> I'm talking about that "Monitor of SOMETHING". Audio devices in
> pulseaudio are represented by sinks (playback devices) and sources
> (capture devices). Each sink has a monitor source associated with it,
> and the monitor source can be used to record what is being played to
> the sink.
> Since you're recording from jack and not from pulseaudio, you're
> definitely not using any monitor sources.
>> Settings like the sample rate/number of channels/… are set to be the
>> same for my entire audio chain, to avoid possible sound modifications
>> like resampling. Yes I think it will not be more than 48000 Hz / 2 channels.
>> As you said, duplicated values (plus you said it is a bug) are related
>> to rewinds. So no rewinds in the log = no possible duplicated values.
>> If I understood, in my case, you cannot confirm 0 dB is the only result
>> I could have in case of problems? (because you think I can have other
>> problems than underruns?)
> Underruns are the only problem that you can have, unless there's
> something that I haven't thought of.


Thank you very much Tanu for your answers. If you come across other 
possible problems which result other than 0 dB (random values for 
example) for this[my] case, please, if possible, share them in this 
thread before one month.

Before one month because I will unsubscribe from the mailing list one 
month after the last reply to this thread, so no more notifications. 
Anyway, I will check the changelogs to see if you come across problems 
which are related to this[my] case—but I hope there will be none!

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