[gst-devel] Dynamic pipelines

[Martin Rubli]

Sebastian, Rob,

Thanks for your tips, I've done a little more testing ...

Setting "sync = false" on the audio sink didn't help for me. If anything,  
it made the problem slightly worse, but it's really hard to tell because  
of all the randomness.

Pausing the pipeline has different effects, depending on what you pause  
(the entire pipeline, the source, the sink) and what kind of stream (audio  
or video) it is. For audio I couldn't get it to work with either of those  
three. For video, however, it helps if I pause the v4l2src. I don't know  
where these different results come from because the code is basically the  
same, but if I find out, I'm going to post it here.

In the meantime I'm going to check out the Farsight source, maybe I'll  
find something that I do differently.

Cheers,
Martin


On Mon, 12 Jun 2006 04:45:57 -0700, Rob Taylor <robtaylor at floopily.org>  
wrote:

> Did you pause the pipeline before linking pads? We do this in Farsight,
> and it works well for us.
>
> Thanks,
> Rob Taylor
> Sébastien Moutte wrote:
>> Hi Martin,
>>
>> I already have this kind of discontinuities with a pipeline which has an
>> audio playback bin (queue ! decoder ! audioconvert ! directsoundsink)
>> that i was adding and removing from the main pipeline.
>> after reconnections, i was getting a silence of a few seconds and next
>> the sound was coming back.
>> I think your message "resync after discont with previous sample " could
>> come from the ring buffer of the audio sink base class.
>> You can try to disable synchronization on the audio sink by setting the
>> "sync" property to false, it worked for me.
>>
>> I hope it will help ...
>> Sebastien
>>
>> Martin Rubli a écrit :
>>> Hi,
>>>
>>> Given the number of replies I have received (zero ;-), dynamically
>>> changing pipelines at play time doesn't seem very popular ...
>>>
>>> Has anyone tried this before and got it to work properly? If so, I'd be
>>> very grateful for sample code to compare it with mine, so that I know
>>> whether my code is wrong or whether I should file a bug against  
>>> GStreamer.
>>>
>>> Thanks!
>>> Martin
>>>
>>>
>>> On Thu, 25 May 2006 16:02:42 -0700, Martin Rubli
>>> <martin_rubli at logitech.com> wrote:
>>>
>>>
>>>> Hi all,
>>>>
>>>> I've been doing some tests with dynamic insertion and removal of
>>>> plug-ins.
>>>>
>>>> The program I've been using is based on section 17.3 of the  
>>>> Application
>>>> Development Manual. (BTW: The sample given on that page needs a few
>>>> changes to work with GStreamer 0.10.)
>>>>
>>>> I have tried different scenarios. In each case the pipeline looks
>>>> something like this and is automatically created. (Using an .ogg file
>>>> here
>>>> but the same thing happens with other audio sources.)
>>>>
>>>> filesrc ! oggdemux ! vorbisdec ! audioresample ! audioconvert !  
>>>> FilterBin
>>>> ! alsasink
>>>>
>>>> The FilterBin is a bin that contains one of the following (defined at
>>>> compile time):
>>>> a) identity
>>>> b) audioresample ! audio/x-raw-int ! identity
>>>> c) audioresample ! audio/x-raw-int, rate=48000 ! identity
>>>> d) audioresample ! audio/x-raw-int, rate=8000 ! identity
>>>>
>>>> Every 5 seconds the FilterBin is taken out of the pipeline or put back
>>>> in,
>>>> so that e.g. in case d) the audio should toggle between normal and  
>>>> pretty
>>>> bad quality.
>>>>
>>>> The problem is that the behavior is somewhat random for some of the
>>>> cases.
>>>> For cases a and b it works consistently well (audioresample should be  
>>>> a
>>>> no-op). In cases c and d, however, I sometimes get interruptions of a
>>>> couple of seconds and the debug log gives lines like:
>>>>
>>>> <AlsaSink> resync after discont with previous sample of diff: 425761
>>>>
>>>> My questions now: Where do these discontinuities come from and what  
>>>> can I
>>>> do about it? Are there any more programs out there that do the same
>>>> thing?
>>>>
>>>> Different variations of changing the pipeline state during the
>>>> insertion/removal phase didn't help either. The test code is attached.
>>>>
>>>> I'd be grateful for any tips ... Cheers,
>>>> Martin
>>>>
>>>
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>>
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