stuck pipeline

[Gary Thomas]

On 2013-02-18 08:16, Tim-Philipp Müller wrote:
> On Mon, 2013-02-18 at 08:05 -0700, Gary Thomas wrote:
>
>> I'm trying to write a pipeline which is equivalent to 'playbin2'
>> to display an MP4 file (H.264+MP3) on my X based display.  I'm doing
>> this to provide finer control over the result, e.g. choice of H.264
>> decoder, etc.
>
> What's the "etc." ?
>
> If you prefer a certain h264 decoder, why not just give it a higher rank
> than the others (you can do that in your application, fwiw, though not
> with gst-launch, unless you change the decoder's source code)?

Eventually this may be useful but for now I just wanted a simple test
using gst-launch.  I was hoping that the pipeline I wrote was more or
less equivalent to using playbin2.

>
>> I tried this pipeline:
>>     gst-launch -v filesrc location=/dcim/Camera/2013-02-18_12-35-40.mp4 ! qtdemux name=demux \
>>       demux. ! queue ! h264parse ! ffdec_h264 ! ffmpegcolorspace ! autovideosink \
>>       demux. ! queue ! mpegaudioparse ! ffdec_mp3 ! audioconvert ! pulsesink
>>
>> Which starts out happy - it brings up a window with the image, but then
>> it just gets stuck.  There is no indication or error why.
>
> You also want a videoscale in front of the videosink in case your sink
> can't scale (like ximagesink). But that's not the reason if it comes up
> in the first place.

Good to know but as you say if it gets started that's not the issue.

>
>> I then tried the [arguably] simpler pipeline and it also gets stuck:
>>     gst-launch -v filesrc location=/dcim/Camera/2013-02-18_12-35-40.mp4 ! qtdemux name=demux \
>>       demux. ! queue ! h264parse ! filesink location=/tmp/junk.h264 \
>>       demux. ! queue ! mpegaudioparse ! filesink location=/tmp/junk.wav
>>
>> Any ideas why this is happening?  Where should I look?
>
> If you just want some sink for testing, you can use fakesink.
>
> The reason it stalls might be that the queues are too small. Either make
> them larger by increasing the max-size-* limits, or use a multiqueue.

My files are *tiny* (less than 500KB) just for testing so I don't see
how the size of the queue could make a difference.  I did try multiqueue
and the results are the same.

>
> Btw, uridecodebin/decodebin2 also give you a way to influence the
> plugging of parsers/decoders/etc. via the autoplug-* signals, so you can
> pick/prefer certain decoders there if you like.

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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