[FFmpeg-devel] [PATCH] vobsub in mov support

[Reimar Döffinger]

On Wed, Apr 01, 2009 at 12:54:10AM -0700, Baptiste Coudurier wrote:
> > ------------------------------------------------------------------------
> > 
> > Index: libavformat/mov.c
> > ===================================================================
> > --- libavformat/mov.c	(revision 18285)
> > +++ libavformat/mov.c	(working copy)
> > @@ -806,7 +806,8 @@
> >                  if(id > 0)
> >                      st->codec->codec_type = CODEC_TYPE_SUBTITLE;
> >              }
> > -        }
> > +        } else if (st->codec->codec_type == CODEC_TYPE_SUBTITLE)
> > +            id = codec_get_id(ff_codec_movsubtitle_tags, format);
> 
> I believe this hunk is not needed.
> 
> >          dprintf(c->fc, "size=%d 4CC= %c%c%c%c codec_type=%d\n", size,
> >                  (format >> 0) & 0xff, (format >> 8) & 0xff, (format >> 16) & 0xff,
> > @@ -997,6 +998,7 @@
> >              // ttxt stsd contains display flags, justification, background
> >              // color, fonts, and default styles, so fake an atom to read it
> >              MOVAtom fake_atom = { .size = size - (url_ftell(pb) - start_pos) };
> > +            if (id != CODEC_ID_DVD_SUBTITLE) // this contains a proper esds atom
> >              mov_read_glbl(c, pb, fake_atom);
> >              st->codec->codec_id= id;
> >              st->codec->width = sc->width;
> 
> This hunk should be sufficient

No, certainly not. ff_codec_movsubtitle_tags is only consulted for
CODEC_TYPE_DATA, never for CODEC_TYPE_SUBTITLE, and in addition it is
also skipped explicitly for mp4s (without that it would be overridden
from CODEC_TYPE_SUBTITLE to CODEC_TYPE_VIDEO).
The whole code is either very carefully crafted and severely lacking
documentation or a very big piece of nonsense.
But as I mentioned in the original message, this would work, but I do
not know if it might break playback of some files completely:
Index: libavformat/mov.c
===================================================================
--- libavformat/mov.c   (revision 18274)
+++ libavformat/mov.c   (working copy)
@@ -997,6 +997,7 @@
             // ttxt stsd contains display flags, justification,
             // background
             // color, fonts, and default styles, so fake an atom to
             // read it
             MOVAtom fake_atom = { .size = size - (url_ftell(pb) - start_pos) };
+            if (id > 0)
             mov_read_glbl(c, pb, fake_atom);
             st->codec->codec_id= id;
             st->codec->width = sc->width;