Hi Yusuke,

On Wed, 22 Feb 2017, Yusuke Nakamura wrote:

2017-02-20 6:22 GMT+09:00 Martin Storsjö <[email protected]>:

In these cases, the CTTS flag is set, but no edit list is necessary.
---
 libavformat/movenc.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 713c145..f1c2253 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1811,8 +1811,7 @@ static int mov_write_trak_tag(AVIOContext *pb,
MOVMuxContext *mov,
     ffio_wfourcc(pb, "trak");
     mov_write_tkhd_tag(pb, mov, track, st);
     if (track->start_dts != AV_NOPTS_VALUE &&
-        (track->mode == MODE_PSP || track->flags & MOV_TRACK_CTTS ||
-        track->start_dts || is_clcp_track(track))) {
+        (track->mode == MODE_PSP || track->start_dts ||
is_clcp_track(track))) {
         if (mov->use_editlist)
             mov_write_edts_tag(pb, mov, track);  // PSP Movies require
edts box
         else if ((track->entry && track->cluster[0].dts) || track->mode
== MODE_PSP || is_clcp_track(track))
--
2.10.1 (Apple Git-78)

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I dislike this patch since an implicit one‐to‐one mapping of presentation
timeline and media timeline does not specify the relative rate. For
example, QuickTime plays a track at double rate relative to a corresponding
media if the media duration is twice as much as the track duration.

I don't really follow in which concrete case this patch would make a difference? With patch 1/3 applied, if one enables the negative_cts_offsets flag that I added, one will end up with an unnecessary edit list. As far as I can see right now, this is the only case where this patch (currently) would make any difference.

Is there any case where it's beneficial to write out an edit list even though it's with media_time = 0, and with the full duration of the track?

// Martin
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