set sample rate for amr to allow stream copy since no decoder is present,

3gp does not store sample rate in stsd in fact. Fixes #674.

Originally committed as revision 15536 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/mov.c

@@ -991,6 +991,9 @@ static int mov_read_stsd(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
     case CODEC_ID_AMR_WB:
         st->codec->frame_size= sc->samples_per_frame;
         st->codec->channels= 1; /* really needed */
+        /* force sample rate for amr, stsd in 3gp does not store sample rate */
+        if (st->codec->codec_id != CODEC_ID_QCELP)
+            st->codec->sample_rate = 8000;
         break;
     case CODEC_ID_MP2:
     case CODEC_ID_MP3: