[vlc-devel] [PATCH] pulse: fix audio dropout when the input buffering takes too long

[Jonathan Calmels]

I see, so something more like that ? Would it always work ?

2015-02-22 18:46 GMT+01:00 Rémi Denis-Courmont <remi at remlab.net>:

> Le dimanche 22 février 2015, 18:17:13 Jonathan Calmels a écrit :
> > From my understanding, even though the negative latency is counter
> > intuitive as you said,
>
> Negative latency is physically impossible. I suppose, in theory, you could
> define a virtual output with negative latency, but that would be mostly
> pointless and (AFAICT) against the PulseAudio design.
>
> > it works because the core compensates when it sees the drift.
>
> Mathematically, a negative PulseAudio stream latency would result in a high
> positive VLC TimeGet delay. In extreme cases, it might cancel out.
>
> But in not so extreme cases, it will trigger unwanted up-sampling.
>
> > I still don't know how to fix it properly though. Hence my request for
> > better suggestions.
>
> I don't know what problem you are trying to solve, because the patch
> description makes no sense.
>
> Ignoring the description and looking only at the patch, it seems you want
> to
> deal with the read pointer overtaking write pointer. That is not called
> negative latency, that is called buffer under-run.
>
> Treating it as negative latency will *not* solve audio drop-outs. At best,
> PulseAudio will discard the written samples up to the read pointer. Since
> they
> would anyway be discarded, resetting the stream or fast-forwarding up to
> the
> point of zero delay is preferable.
>
> --
> Rémi Denis-Courmont
> http://www.remlab.net/
>
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