Bug#863663: libgstreamer1.0-0: plays MJPEG AVI files (and possibly other formats) at degraded quality

[Francesco Poli]

On Tue, 27 Jun 2017 23:34:08 +0200 Francesco Poli wrote:

[...]
> Is there any alternative approach?

Just to clarify: while waiting for [bug 783267] to be fixed[^NOTE],
I am looking for a workaround.

[bug 783267]: <https://bugzilla.gnome.org/show_bug.cgi?id=783267>

[^NOTE]: by the way, is there any progress?!? could someone please
         fix the bug once and for all?!?

I was trying to adjust the ranks from within the application in order
to convince the GStreamer library to select the equivalent of the
following pipeline for MJPEG AVI files:

  $ gst-launch-1.0 filesrc location=wave_anim.avi \! avidemux \! jpegparse \! avdec_mjpeg \! videoconvert \! autovideosink

But all my attempts seem to fail.

On the other hand, since in my use case all the movies are MJPEG AVI
files, another temporary workaround could be to force the above
pipeline manually.

Could someone please help me?

The application is pdf-presenter-console also known as [pdfpc].
The code that sets the GStreamer pipeline is (I think) in the
establish_pipeline() method included in the file
[src/classes/action/movie.vala].
I believe that this method sets up a generic pipeline (suitable for any
file format supported by GStreamer).
How should I modify that method to force the use of the above mentioned
pipeline (avidemux \! jpegparse \! avdec_mjpeg \! videoconvert), which
is only suitable for MJPEG AVI files?

[pdfpc]: <https://pdfpc.github.io/>

[src/classes/action/movie.vala]: <https://github.com/pdfpc/pdfpc/blob/d1c17b0d91f0dcd2128ec60086c86d3d8dc251c4/src/classes/action/movie.vala>


 
> P.S.: Please Cc me, as well as the Debian bug address and the
> gstreamer-devel mailing list. Thanks for your understanding!


-- 
 http://www.inventati.org/frx/
 There's not a second to spare! To the laboratory!
..................................................... Francesco Poli .
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