movenc: Make tkhd "enabled" flag QuickTime compatible

QuickTime will play multiple audio tracks concurrently if this flag is
set for multiple audio tracks.  And if no subtitle track has this flag
set, QuickTime will show no subtitles in the subtitle menu.

Signed-off-by: Anton Khirnov <anton@khirnov.net>

2 files changed, 56 insertions, 1 deletions

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 0c6b09da8e..577c7e848e 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1391,7 +1391,9 @@ static int mov_write_tkhd_tag(AVIOContext *pb, MOVTrack *track, AVStream *st)
     (version == 1) ? avio_wb32(pb, 104) : avio_wb32(pb, 92); /* size */
     ffio_wfourcc(pb, "tkhd");
     avio_w8(pb, version);
-    avio_wb24(pb, 0xf); /* flags (track enabled) */
+    avio_wb24(pb, (track->flags & MOV_TRACK_ENABLED) ?
+                  MOV_TKHD_FLAG_ENABLED | MOV_TKHD_FLAG_IN_MOVIE :
+                  MOV_TKHD_FLAG_IN_MOVIE);
     if (version == 1) {
         avio_wb64(pb, track->time);
         avio_wb64(pb, track->time);
@@ -3028,6 +3030,56 @@ static int mov_create_chapter_track(AVFormatContext *s, int tracknum)
     return 0;
 }
 
+/*
+ * st->disposition controls the "enabled" flag in the tkhd tag.
+ * QuickTime will not play a track if it is not enabled.  So make sure
+ * that one track of each type (audio, video, subtitle) is enabled.
+ *
+ * Subtitles are special.  For audio and video, setting "enabled" also
+ * makes the track "default" (i.e. it is rendered when played). For
+ * subtitles, an "enabled" subtitle is not rendered by default, but
+ * if no subtitle is enabled, the subtitle menu in QuickTime will be
+ * empty!
+ */
+static void enable_tracks(AVFormatContext *s)
+{
+    MOVMuxContext *mov = s->priv_data;
+    int i;
+    uint8_t enabled[AVMEDIA_TYPE_NB];
+    int first[AVMEDIA_TYPE_NB];
+
+    for (i = 0; i < AVMEDIA_TYPE_NB; i++) {
+        enabled[i] = 0;
+        first[i] = -1;
+    }
+
+    for (i = 0; i < s->nb_streams; i++) {
+        AVStream *st = s->streams[i];
+
+        if (st->codec->codec_type <= AVMEDIA_TYPE_UNKNOWN ||
+            st->codec->codec_type >= AVMEDIA_TYPE_NB)
+            continue;
+
+        if (first[st->codec->codec_type] < 0)
+            first[st->codec->codec_type] = i;
+        if (st->disposition & AV_DISPOSITION_DEFAULT) {
+            mov->tracks[i].flags |= MOV_TRACK_ENABLED;
+            enabled[st->codec->codec_type] = 1;
+        }
+    }
+
+    for (i = 0; i < AVMEDIA_TYPE_NB; i++) {
+        switch (i) {
+        case AVMEDIA_TYPE_VIDEO:
+        case AVMEDIA_TYPE_AUDIO:
+        case AVMEDIA_TYPE_SUBTITLE:
+            if (!enabled[i] && first[i] >= 0)
+                mov->tracks[first[i]].flags |= MOV_TRACK_ENABLED;
+            break;
+        }
+    }
+}
+
 static int mov_write_header(AVFormatContext *s)
 {
     AVIOContext *pb = s->pb;
@@ -3182,6 +3234,8 @@ static int mov_write_header(AVFormatContext *s)
         }
     }
 
+    enable_tracks(s);
+
     if (mov->mode == MODE_ISM) {
         /* If no fragmentation options have been set, set a default. */
         if (!(mov->flags & (FF_MOV_FLAG_FRAG_KEYFRAME |
diff --git a/libavformat/movenc.h b/libavformat/movenc.h
index a6282e14c7..78001cc3f2 100644
--- a/libavformat/movenc.h
+++ b/libavformat/movenc.h
@@ -85,6 +85,7 @@ typedef struct MOVTrack {
     int         has_keyframes;
 #define MOV_TRACK_CTTS         0x0001
 #define MOV_TRACK_STPS         0x0002
+#define MOV_TRACK_ENABLED      0x0004
     uint32_t    flags;
     int         language;
     int         track_id;