[FFmpeg-devel] [PATCH 2/2] movenc: support an alternative to edit lists to handle the first DTS != 0 case.

[Michael Niedermayer]

Some software does not support edit lists at all, the adobe flash
player seems to be one of these. Which results in AV sync errors when
edit lists are used to adjust AV sync.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
---
 libavformat/movenc.c |   15 ++++++++++++++-
 libavformat/movenc.h |    3 +++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index ded2859..ff47d09 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -61,6 +61,7 @@ static const AVOption options[] = {
     { "min_frag_duration", "Minimum fragment duration", offsetof(MOVMuxContext, min_fragment_duration), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM},
     { "frag_size", "Maximum fragment size", offsetof(MOVMuxContext, max_fragment_size), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM},
     { "ism_lookahead", "Number of lookahead entries for ISM files", offsetof(MOVMuxContext, ism_lookahead), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM},
+    { "use_editlist", "use edit list", offsetof(MOVMuxContext, use_editlist), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, AV_OPT_FLAG_ENCODING_PARAM},
     { NULL },
 };
 
@@ -83,6 +84,12 @@ static int64_t update_size(AVIOContext *pb, int64_t pos)
     return curpos - pos;
 }
 
+static int supports_edts(MOVMuxContext *mov)
+{
+    // EDTS with fragments is tricky as we dont know the duration when its written
+    return (mov->use_editlist<0 && !(mov->flags & FF_MOV_FLAG_FRAGMENT)) || mov->use_editlist>0;
+}
+
 static int is_co64_required(const MOVTrack *track)
 {
     int i;
@@ -1745,7 +1752,7 @@ static int mov_write_trak_tag(AVIOContext *pb, MOVMuxContext *mov,
     avio_wb32(pb, 0); /* size */
     ffio_wfourcc(pb, "trak");
     mov_write_tkhd_tag(pb, track, st);
-    if (!(mov->flags & FF_MOV_FLAG_FRAGMENT)) // EDTS with fragments is tricky as we dont know the duration when its written
+    if (supports_edts(mov))
         mov_write_edts_tag(pb, track);  // PSP Movies and several other cases require edts box
     if (track->tref_tag)
         mov_write_tref_tag(pb, track);
@@ -3143,6 +3150,11 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
     if (pkt->dts != pkt->pts)
         trk->flags |= MOV_TRACK_CTTS;
     trk->cluster[trk->entry].cts = pkt->pts - pkt->dts;
+    if (!supports_edts(mov)) {
+        if (trk->dts_shift == AV_NOPTS_VALUE)
+            trk->dts_shift = pkt->dts;
+        trk->cluster[trk->entry].cts += trk->dts_shift;
+    }
     trk->cluster[trk->entry].flags = 0;
     if (enc->codec_id == AV_CODEC_ID_VC1) {
         mov_parse_vc1_frame(pkt, trk, mov->fragments);
@@ -3512,6 +3524,7 @@ static int mov_write_header(AVFormatContext *s)
          * this is updated. */
         track->hint_track = -1;
         track->start_dts = AV_NOPTS_VALUE;
+        track->dts_shift = AV_NOPTS_VALUE;
         if(st->codec->codec_type == AVMEDIA_TYPE_VIDEO){
             if (track->tag == MKTAG('m','x','3','p') || track->tag == MKTAG('m','x','3','n') ||
                 track->tag == MKTAG('m','x','4','p') || track->tag == MKTAG('m','x','4','n') ||
diff --git a/libavformat/movenc.h b/libavformat/movenc.h
index da6f19b..cc718de 100644
--- a/libavformat/movenc.h
+++ b/libavformat/movenc.h
@@ -106,6 +106,7 @@ typedef struct MOVIndex {
     uint32_t    tref_tag;
     int         tref_id; ///< trackID of the referenced track
     int64_t     start_dts;
+    int64_t     dts_shift;
 
     int         hint_track;   ///< the track that hints this track, -1 if no hint track is set
     int         src_track;    ///< the track that this hint (or tmcd) track describes
@@ -165,6 +166,8 @@ typedef struct MOVMuxContext {
     int max_fragment_size;
     int ism_lookahead;
     AVIOContext *mdat_buf;
+
+    int use_editlist;
 } MOVMuxContext;
 
 #define FF_MOV_FLAG_RTP_HINT 1
-- 
1.7.9.5