print stream index in error message

Originally committed as revision 12605 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -1237,7 +1237,8 @@ static int mov_read_trak(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
     /* sanity checks */
     if(!sc->stts_count || !sc->chunk_count || !sc->sample_to_chunk_sz ||
        (!sc->sample_size && !sc->sample_count)){
-        av_log(c->fc, AV_LOG_ERROR, "missing mandatory atoms, broken header\n");
+        av_log(c->fc, AV_LOG_ERROR, "stream %d, missing mandatory atoms, broken header\n",
+               st->index);
         sc->sample_count = 0; //ignore track
         return 0;
     }