[MPlayer-users] Re: Unable to decode TS stream after aspect ratio change

[Zed]

> The problem is not the decoding, and certainly not the aspect change.
  You are quite right, my bad. I came to the wrong conclusion since the aspect
ratio change was the only visible aspect of the original source material, even
though the sample I cut out did not include this aspect ratio change.

> First, it only happens with some vos, so this is a very good example why
  Again quite right. I have narrowed down the problem to a resolution change.
The problem occurs when the resolution of the TS stream changed down from
720x576 to 704x576. Interestingly enough there is no problem going the other
way.

> you really should have included a full "mplayer -v" log, which is
> supposed to be the minimum requirement for every bug report.
  I, perhaps wrongly, assumed that this was redundant as the problems were not
specific to a certain version and the source material exhibiting the issue was
provided.

  However, I stand corrected and have uploaded the original material and a few
new clips to demonstrate the issue to:
  ftp://upload.mplayerhq.hu/MPlayer/incoming/rezchange/

  The following files are provided:
  ww.ts - the original material with a resolution change down (720->704)
  rezdown.ts - a new clip that demonstrates that the problem is replicable with
other material
  rezup.ts  - a new clip which shows that there is no problem the other way
(704->720)
  aspect.ts - a new clip which contains an aspect ratio change from 4:3 to 16:9

  In addition four txt files are provided and they contain the output of mplayer
-v for each file in question.

  The aspect.ts has no playback problems, but I included it here due to the fact
that I'm having a hard time maintaining the correct aspect ratio after the
change. I've tried to scale the video and tried to apply the instructions in
13.10 Preserving aspect ratio (see below), but without result. I always end up
with a 4:3 aspect ration for the whole file regardless of the change to 16:9.

mencoder aspect.ts -ovc lavc -lavcopts 
vcodec=mpeg4:mbd=2:trell:autoaspect
-vf crop=714:548:0:14 -oac copy -o aspect.avi

  I uploaded the transcoded file (aspect.avi) and the mencoder output
(mencoder_aspect.txt) and mplayer -v output (mplayer_aspect.txt)

  For some reason I am unable to upload to the rezchange directory and thus the
aspect change files are in 
ftp://upload.mplayerhq.hu/MPlayer/incoming/aspect_change/

> Second, the problem is not aspect change, but that the resolution of the
> video changes - so no wonder that you have no chance to encode it, you
> would at minimum have to insert a scale filter to keep the encoding size
> constant.
  Could you please elaborate on this suggestion? I have tried different -vf
scale filters but with little use. I read the manual and I understood that the
scale filters are applied postprocess and not preprocess. Don't I need to
preprocess the input file in order to correct any resolution changes before
handing over the file to mencoder in this proposed workaround? On that topic,
any suggestions on such preprocess tools? Obviously I would prefer to use
mencoder for the whole transcode process, if possible.

> Problems at least partially fixed in SVN r20607.
  Thank you for the effort. I shall see if I can manage to get this new version
compiled. Subversion or compilers are not my fortes as an end user.

- Zed

P.S. Is it possible to autobreak over 80 character lines or at least highlight
the offending lines when posting though the post form?

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