avformat/mov: only force parsing for video tracks if stss is empty

Fixes playback of some AAC streams, which are otherwise mangled by the
parser, and stss is typically only valid for video anyway.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/mov.c

@@ -1779,7 +1779,7 @@ static int mov_read_stss(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     if (!entries)
     {
         sc->keyframe_absent = 1;
-        if (!st->need_parsing)
+        if (!st->need_parsing && st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
             st->need_parsing = AVSTREAM_PARSE_HEADERS;
         return 0;
     }