Add non standard id needed for dvd subtitles.

Originally committed as revision 11626 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/isom.c

@@ -47,6 +47,7 @@ const AVCodecTag ff_mp4_obj_type[] = {
     { CODEC_ID_JPEG2000  , 110 }, /* 15444-1 */
     { CODEC_ID_VC1       , 163 },
     { CODEC_ID_VORBIS    , 221 }, /* non standard, gpac uses it */
+    { CODEC_ID_DVD_SUBTITLE, 224 }, /* non standard, see unsupported-embedded-subs-2.mp4 */
     { CODEC_ID_QCELP     , 225 },
     { 0, 0 },
 };