alsasink, sync=false and pipeline clocking

[Chris Tapp]

I've been having audio problems (glitches, dropouts) when using pipelines of the form:

  playbin uri=<live-mpegts-stream> audio-sink="alsasink"

It appears that setting sync=false in the alsasink stops the glitches, so I suspect they're being caused by a clock mismatch between the pipeline clock and the (implied) clock from the mpegts stream.

However, running with sync=false means that, as expected, the audio and video drift out of step with each other. How can I maintain a reasonable level of sync between the audio and video? I think this has something to do with the discont-wait, drift-tolerance and alignment-threshold properties of alsasink, but I can't find a set of values that work that well. Is there a document somewhere that explains exactly what these parameters do? I've looked at the output of `gst-inspect alsasink`, but that doesn't explain how these parameters are related.

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Chris Tapp
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[Adrian Pardini]

On 9 January 2015 at 05:56, Chris Tapp <[hidden email]> wrote:
> I've been having audio problems (glitches, dropouts) when using pipelines of the form:
>
>   playbin uri=<live-mpegts-stream> audio-sink="alsasink"
>
> It appears that setting sync=false in the alsasink stops the glitches, so I suspect they're being caused by a clock mismatch between the pipeline clock and the (implied) clock from the mpegts stream.


Hi Chris, probably not directly related to your problem but look at:

https://bugzilla.gnome.org/show_bug.cgi?id=692953
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[Chris Tapp]

On 9 Jan 2015, at 12:26, Adrian Pardini <[hidden email]> wrote:

> On 9 January 2015 at 05:56, Chris Tapp <[hidden email]> wrote:
>> I've been having audio problems (glitches, dropouts) when using pipelines of the form:
>>
>>  playbin uri=<live-mpegts-stream> audio-sink="alsasink"
>>
>> It appears that setting sync=false in the alsasink stops the glitches, so I suspect they're being caused by a clock mismatch between the pipeline clock and the (implied) clock from the mpegts stream.
>
>
> Hi Chris, probably not directly related to your problem but look at:
>
> https://bugzilla.gnome.org/show_bug.cgi?id=692953

Thanks. I had already spotted that one when trying to work out what's going on. As you say, I don't think its directly related.

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Chris Tapp
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[Chris Tapp]

Update:

1) I'm also getting the same glitches/dropouts if I switch to using pulseaudio.
2) Audio is fine if I start an audiotestsrc pipeline running when the problem with the mpegts stream is showing (i.e. at the same time).

It looks to me more as if its a problem with the pipeline itself rather than the audiosink.

On 9 Jan 2015, at 20:54, Chris Tapp <[hidden email]> wrote:

>
> On 9 Jan 2015, at 12:26, Adrian Pardini <[hidden email]> wrote:
>
>> On 9 January 2015 at 05:56, Chris Tapp <[hidden email]> wrote:
>>> I've been having audio problems (glitches, dropouts) when using pipelines of the form:
>>>
>>> playbin uri=<live-mpegts-stream> audio-sink="alsasink"
>>>
>>> It appears that setting sync=false in the alsasink stops the glitches, so I suspect they're being caused by a clock mismatch between the pipeline clock and the (implied) clock from the mpegts stream.
>>
>>
>> Hi Chris, probably not directly related to your problem but look at:
>>
>> https://bugzilla.gnome.org/show_bug.cgi?id=692953
>
> Thanks. I had already spotted that one when trying to work out what's going on. As you say, I don't think its directly related.
>
> --
>
> Chris Tapp
> [hidden email]
> www.keylevel.com
>
> _______________________________________________
> gstreamer-devel mailing list
> [hidden email]
> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel

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Chris Tapp
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[cchilumbu]

Hi Chris,

Did you fix this problem? I am having the exact issue and would like to know if you fixed it.

I am using pulsesink and getting a lot of undertow messages, which results in audible glitches.

Thank you