alsasrc vs pulsesrc clocks and timestamps

mattes effemm at
Tue Apr 15 22:52:45 PDT 2014

On Mon, 14 Apr 2014 21:06:15 -0700 "mattes" <effemm at> wrote

> There seems to be a difference in timestamp behaviour depending on the audio
> source plugin used.  
> I used the following pipeline:
>   alsasrc -> audioconvert -> faac -> qtmux -> filesink
> I start a recording and after X seconds I switch to PAUSE.
> Waiting Y seconds I switch to PLAYING again, to resume the recording.
> I noticed that the timestamps do not reflect the paused 'Y' duration.
> Instead timestamps continue as if Pause never happened.
> The timestamps after the pause continue at Z time (= X+Y seconds).
> This results in an issue some player (demuxer) can't tolerate, when
> the timestamp jumps from X to Z.
> I tried to use different clocks but that does not make difference for me.
> Next, I replaced the audio source with 'pulsesrc'. Surprisingly this behaves
> different. When pausing the recording and resuming after Y seconds, the
> timestamps continue in order without the (Y second) jump.
> What can be done to make 'alsasrc' to do the same as pulsesrc does,
> when switching from pausing and playing again?
Forgot to mention, this was tested with GStreamer 1.0.10

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