From: Mengyang Yuan <manuely...@163.com>
In this case, the input video is of dynamic frame rate and we don't want to
duplicate or drop frames, but the output video duration calculated by DTS is
incorrect, I solved it by using PTS.
There are many UGC videos with dynamic frame rates, which are represented by
PTS jumps. After transcoding with ffmpeg -vsync 0 or -vsync 2, the output
video duration becomes longer.By reading the code of x264/encoder/encoder.c,
I found that in order to predict the B frame, x264 needs to ensure that there
are enough reference frames when DTS = 0, so the DTS of these reference frames
will subtract the cache time. However, the cache time includes the part of PTS
jumps, which results in the abnormal small DTS.
Signed-off-by: Mengyang Yuan <manuely...@163.com>
---
libavformat/movenc.c | 23 ++++++++++++++---------
libavformat/movenc.h | 2 ++
2 files changed, 16 insertions(+), 9 deletions(-)
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 715bec1c2f..206aa48d8c 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1015,7 +1015,7 @@ static int get_cluster_duration(MOVTrack *track, int
cluster_idx)
return 0;
if (cluster_idx + 1 == track->entry)
- next_dts = track->track_duration + track->start_dts;
+ next_dts = track->end_dts;
else
next_dts = track->cluster[cluster_idx + 1].dts;
@@ -5149,8 +5149,7 @@ static int mov_flush_fragment(AVFormatContext *s, int
force)
mov->mdat_size = 0;
for (i = 0; i < mov->nb_streams; i++) {
if (mov->tracks[i].entry)
- mov->tracks[i].frag_start += mov->tracks[i].start_dts +
- mov->tracks[i].track_duration -
+ mov->tracks[i].frag_start += mov->tracks[i].end_dts -
mov->tracks[i].cluster[0].dts;
mov->tracks[i].entry = 0;
mov->tracks[i].end_reliable = 0;
@@ -5208,7 +5207,7 @@ static int mov_flush_fragment(AVFormatContext *s, int
force)
int64_t duration = 0;
if (track->entry)
- duration = track->start_dts + track->track_duration -
+ duration = track->end_dts -
track->cluster[0].dts;
if (mov->flags & FF_MOV_FLAG_SEPARATE_MOOF) {
if (!track->mdat_buf)
@@ -5281,7 +5280,7 @@ static int check_pkt(AVFormatContext *s, AVPacket *pkt)
ref = trk->cluster[trk->entry - 1].dts;
} else if ( trk->start_dts != AV_NOPTS_VALUE
&& !trk->frag_discont) {
- ref = trk->start_dts + trk->track_duration;
+ ref = trk->end_dts;
} else
ref = pkt->dts; // Skip tests for the first packet
@@ -5494,7 +5493,7 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
* of the last packet of the previous fragment based on
track_duration,
* which might not exactly match our dts. Therefore adjust the dts
* of this packet to be what the previous packets duration
implies. */
- trk->cluster[trk->entry].dts = trk->start_dts +
trk->track_duration;
+ trk->cluster[trk->entry].dts = trk->end_dts;
/* We also may have written the pts and the corresponding duration
* in sidx/tfrf/tfxd tags; make sure the sidx pts and duration
match up with
* the next fragment. This means the cts of the first sample must
@@ -5546,13 +5545,17 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket
*pkt)
"this case.\n",
pkt->stream_index, pkt->dts);
}
- trk->track_duration = pkt->dts - trk->start_dts + pkt->duration;
- trk->last_sample_is_subtitle_end = 0;
-
if (pkt->pts == AV_NOPTS_VALUE) {
av_log(s, AV_LOG_WARNING, "pts has no value\n");
pkt->pts = pkt->dts;
}
+ if (trk->start_pts == AV_NOPTS_VALUE) {
+ trk->start_pts = pkt->pts;
+ }
+ trk->track_duration = FFMAX(pkt->pts - trk->start_pts + pkt->duration,
trk->track_duration);
+ trk->end_dts = pkt->dts + pkt->duration;
+ trk->last_sample_is_subtitle_end = 0;
+
if (pkt->dts != pkt->pts)
trk->flags |= MOV_TRACK_CTTS;
trk->cluster[trk->entry].cts = pkt->pts - pkt->dts;
@@ -6295,7 +6298,9 @@ static int mov_init(AVFormatContext *s)
* this is updated. */
track->hint_track = -1;
track->start_dts = AV_NOPTS_VALUE;
+ track->start_pts = AV_NOPTS_VALUE;
track->start_cts = AV_NOPTS_VALUE;
+ track->end_dts = AV_NOPTS_VALUE;
track->end_pts = AV_NOPTS_VALUE;
track->dts_shift = AV_NOPTS_VALUE;
if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
diff --git a/libavformat/movenc.h b/libavformat/movenc.h
index 68d6f23a5a..ddad2631d7 100644
--- a/libavformat/movenc.h
+++ b/libavformat/movenc.h
@@ -116,7 +116,9 @@ typedef struct MOVTrack {
uint32_t tref_tag;
int tref_id; ///< trackID of the referenced track
int64_t start_dts;
+ int64_t start_pts;
int64_t start_cts;
+ int64_t end_dts;
int64_t end_pts;
int end_reliable;
int64_t dts_shift;
--
2.17.2 (Apple Git-113)
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