movenc: write 'chan' tag for AC-3 in MOV

libavformat/movenc.c

@@ -386,6 +386,7 @@ static int mov_write_wave_tag(AVIOContext *pb, MOVTrack *track)
     } else if (track->enc->codec_id == CODEC_ID_AMR_NB) {
         mov_write_amr_tag(pb, track);
     } else if (track->enc->codec_id == CODEC_ID_AC3) {
+        mov_write_chan_tag(pb, track);
         mov_write_ac3_tag(pb, track);
     } else if (track->enc->codec_id == CODEC_ID_ALAC) {
         mov_write_extradata_tag(pb, track);