Support DVD subtitles in mov/mp4 as created by Nero.

See also http://samples.mplayerhq.hu/sub/NeroMP4/unsupported-embedded-subs-2.mp4

Originally committed as revision 18314 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -997,6 +997,7 @@ static int mov_read_stsd(MOVContext *c, ByteIOContext *pb, MOVAtom atom)
             // 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 (format != AV_RL32("mp4s")) // mp4s contains a regular esds atom
             mov_read_glbl(c, pb, fake_atom);
             st->codec->codec_id= id;
             st->codec->width = sc->width;