avformat/movenc: write channel descriptions when a known layout or a bitmap can't be used

Fixes part of ticket #2865

Signed-off-by: James Almer <jamrial@gmail.com>

1 files changed, 27 insertions, 10 deletions

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 46d66c29c2..263649f1da 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -867,20 +867,27 @@ static int mov_write_dmlp_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
 
 static int mov_write_chan_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *track)
 {
-    uint32_t layout_tag, bitmap;
+    uint32_t layout_tag, bitmap, *channel_desc;
     int64_t pos = avio_tell(pb);
+    int num_desc, ret;
 
-    layout_tag = ff_mov_get_channel_layout_tag(track->par->codec_id,
-                                               &track->par->ch_layout,
-                                               &bitmap);
-    if (!layout_tag) {
-        av_log(s, AV_LOG_WARNING, "not writing 'chan' tag due to "
-               "lack of channel information\n");
+    if (track->multichannel_as_mono)
         return 0;
+
+    ret = ff_mov_get_channel_layout_tag(track->par, &layout_tag,
+                                        &bitmap, &channel_desc);
+
+    if (ret < 0) {
+        if (ret == AVERROR(ENOSYS)) {
+            av_log(s, AV_LOG_WARNING, "not writing 'chan' tag due to "
+                                      "lack of channel information\n");
+            ret = 0;
+        }
+
+        return ret;
     }
 
-    if (track->multichannel_as_mono)
-        return 0;
+    num_desc = layout_tag ? 0 : track->par->ch_layout.nb_channels;
 
     avio_wb32(pb, 0);           // Size
     ffio_wfourcc(pb, "chan");   // Type
@@ -888,7 +895,17 @@ static int mov_write_chan_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
     avio_wb24(pb, 0);           // Flags
     avio_wb32(pb, layout_tag);  // mChannelLayoutTag
     avio_wb32(pb, bitmap);      // mChannelBitmap
-    avio_wb32(pb, 0);           // mNumberChannelDescriptions
+    avio_wb32(pb, num_desc);    // mNumberChannelDescriptions
+
+    for (int i = 0; i < num_desc; i++) {
+        avio_wb32(pb, channel_desc[i]); // mChannelLabel
+        avio_wb32(pb, 0);               // mChannelFlags
+        avio_wl32(pb, 0);               // mCoordinates[0]
+        avio_wl32(pb, 0);               // mCoordinates[1]
+        avio_wl32(pb, 0);               // mCoordinates[2]
+    }
+
+    av_free(channel_desc);
 
     return update_size(pb, pos);
 }