[FFmpeg-devel] [PATCH v2 16/18] avcodec/avcodec, avformat/movenc: introduced AV_PKT_DATA_TRACK_ALTERNATE_GROUP side data for expressing alternate groups

[Erkki Seppälä]

Alternate groups previously always generated for ISO media files. With
this addition client code can define track groups arbitrarily.

Signed-off-by: Erkki Seppälä <erkki.seppala.ext at nokia.com>
Signed-off-by: OZOPlayer <OZOPL at nokia.com>
---
 libavcodec/avcodec.h | 11 +++++++++++
 libavformat/movenc.c |  9 +++++++++
 2 files changed, 20 insertions(+)

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 4393ac6..0a5abd8 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -1630,6 +1630,17 @@ enum AVPacketSideDataType {
      * AVAudioTrackChannelLayout.
      */
     AV_PKT_DATA_AUDIO_TRACK_CHANNEL_LAYOUT,
+
+    /**
+     * Assign alternate groups for tracks. An example of alternate
+     * groups would be audio tracks (or video tracks) that are
+     * alternative to each other. Each alternative track shares the
+     * same non-zero alternate group.
+     *
+     * The content is:
+     * uint: The alternate group of this track
+     */
+    AV_PKT_DATA_TRACK_ALTERNATE_GROUP,
 };
 
 #define AV_PKT_DATA_QUALITY_FACTOR AV_PKT_DATA_QUALITY_STATS //DEPRECATED
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index bbd176f..abe68ce 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -2565,6 +2565,8 @@ static int mov_write_tkhd_tag(AVIOContext *pb, MOVMuxContext *mov,
     int flags   = MOV_TKHD_FLAG_IN_MOVIE;
     int rotation = 0;
     int group   = 0;
+    int *alternate_group = NULL;
+    int alternate_group_size;
 
     uint32_t *display_matrix = NULL;
     int      display_matrix_size, i;
@@ -2581,6 +2583,13 @@ static int mov_write_tkhd_tag(AVIOContext *pb, MOVMuxContext *mov,
             display_matrix = NULL;
     }
 
+    if (st) {
+        alternate_group = (int*) av_stream_get_side_data(st, AV_PKT_DATA_TRACK_ALTERNATE_GROUP,
+                                                         &alternate_group_size);
+        if (alternate_group && alternate_group_size >= sizeof(int))
+            group = *alternate_group;
+    }
+
     if (track->flags & MOV_TRACK_ENABLED)
         flags |= MOV_TKHD_FLAG_ENABLED;
 
-- 
2.7.4