[Mplayer-advusers] ffmpeg12 error error concealment problem

[Zoltan Hidvegi]

Michael Niedermayer wrote:
> On Sunday 15 February 2004 21:50, Zoltan Hidvegi wrote:
> > I've uploaded the file ffmpeg12-bug.ts to mplayerhq incoming.  Play it
> > with
> >
> > mplayer ffmpeg12-bug.ts -tsprog 2 -vop field,crop=1408:1056:256:16 -nosound
> > -vfm ffmpeg
> >
> > and watch the ugliness.  Now try the same with -vfm libmpeg2, it looks
> > much better.
> remove the crop filter, or add -noslices (or fix slices)
> btw, u also should set -lavdopts er=4

Thanks, I did not know that slices are broken.  But even with
-noslices, it does not look as good as libmpeg2.  It seems that the
same frame is repeated a few times before proceeding.  And there seems
to be an other problem: it coredumps with direct rendering, just try
filmdint or pullup as the first filter.  The reason is that put image
is called twice on the same mpi without and get_image between the two
calls.  The first call clears the mpi->priv field, and when put_image
is called again, it wants to use mpi->priv which is 0.  When I added a
check to not use mpi->priv if it is zero (add an extra condition to
vf_filmdint.c:1145), it dumped in i386/dsputil_mmx.c:365.  It may well
be because of some buffers are not allocated the way vd_ffmpeg expects
it.  What are the exact rules for DR?  The pullup and filmdint filters
use DR to avoid copying but still have access to a limited history of
previous frames, but it seems to work just by change instead of by
design.  E.g. the pullup filter does not work well for mpeg4 without
b-frames, because ffmpeg assumes that get_image will return the same
buffer at every second MP_IMGTYPE_IP type call, and maybe something
similar is happening here.  E.g., vf_filmdint will switch back and
forth between two different temp frames when get_image is called with
MP_IMGTYPE_IPB type and the MP_IMGFLAG_READABLE flag.  This is
different from the default get_image, which always returns the same
temp image.  Maybe that's causing the coredump?

Zoli