avformat/movenc: dont mark multichannel as mono tracks as containing the center channel

Fixes Ticket3727
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/movenc.c

@@ -432,6 +432,9 @@ static int mov_write_chan_tag(AVIOContext *pb, MOVTrack *track)
         return 0;
     }
 
+    if (track->multichannel_as_mono)
+        return 0;
+
     avio_wb32(pb, 0);           // Size
     ffio_wfourcc(pb, "chan");   // Type
     avio_w8(pb, 0);             // Version
@@ -4120,6 +4123,31 @@ static int mov_write_header(AVFormatContext *s)
         }
     }
 
+    for (i = 0; i < s->nb_streams; i++) {
+        int j;
+        AVStream *st= s->streams[i];
+        MOVTrack *track= &mov->tracks[i];
+
+        if (st->codec->codec_type != AVMEDIA_TYPE_AUDIO ||
+            track->enc->channel_layout != AV_CH_LAYOUT_MONO)
+            continue;
+
+        for (j = 0; j < s->nb_streams; j++) {
+            AVStream *stj= s->streams[j];
+            MOVTrack *trackj= &mov->tracks[j];
+            if (j == i)
+                continue;
+
+            if (stj->codec->codec_type != AVMEDIA_TYPE_AUDIO ||
+                trackj->enc->channel_layout != AV_CH_LAYOUT_MONO ||
+                trackj->language != track->language ||
+                trackj->tag != track->tag
+            )
+                continue;
+            track->multichannel_as_mono++;
+        }
+    }
+
     enable_tracks(s);
 
 

libavformat/movenc.h

@@ -100,6 +100,7 @@ typedef struct MOVTrack {
     int         tag; ///< stsd fourcc
     AVStream        *st;
     AVCodecContext *enc;
+    int multichannel_as_mono;
 
     int         vos_len;
     uint8_t     *vos_data;