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From eeb38d760d0748b14c4faed1bfd04efad9ed0806 Mon Sep 17 00:00:00 2001
From: John Stebbins <stebbins@jetheaddev.com>
Date: Sun, 19 Feb 2017 14:45:44 -0700
Subject: [PATCH] mov: fix edit list issue that can cause A/V desync
Only the first entry in the edit list was factored into the time_offset
of the first sample in a track. But when there is a delay (empty edit
entry) the mediatime from the second entry must also be factored into
the time_offset.
---
libavformat/isom.h | 2 ++
libavformat/mov.c | 30 ++++++++++++++++++++++--------
2 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/libavformat/isom.h b/libavformat/isom.h
index 8cc5ab7..7c345e9 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -125,6 +125,8 @@ typedef struct MOVStreamContext {
int *keyframes;
int time_scale;
int64_t time_offset; ///< time offset of the first edit list entry
+ int64_t time_offset_delay;
+ int64_t time_offset_skip;
int current_sample;
unsigned int bytes_per_frame;
unsigned int samples_per_frame;
diff --git a/libavformat/mov.c b/libavformat/mov.c
index 5c9f85c..1657647 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -2323,10 +2323,10 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
uint64_t stream_size = 0;
/* adjust first dts according to edit list */
- if (sc->time_offset && mov->time_scale > 0) {
- if (sc->time_offset < 0)
- sc->time_offset = av_rescale(sc->time_offset, sc->time_scale, mov->time_scale);
- current_dts = -sc->time_offset;
+ if (mov->time_scale > 0) {
+ sc->time_offset = av_rescale(sc->time_offset_delay, sc->time_scale,
+ mov->time_scale) - sc->time_offset_skip;
+ current_dts = sc->time_offset;
}
/* only use old uncompressed audio chunk demuxing when stts specifies it */
@@ -2999,6 +2999,10 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
sc = st->priv_data;
if (sc->pseudo_stream_id+1 != frag->stsd_id)
return 0;
+ if (c->time_scale > 0) {
+ sc->time_offset = av_rescale(sc->time_offset_delay, sc->time_scale,
+ c->time_scale) - sc->time_offset_skip;
+ }
avio_r8(pb); /* version */
flags = avio_rb24(pb);
entries = avio_rb32(pb);
@@ -3029,7 +3033,7 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
}
if (flags & MOV_TRUN_DATA_OFFSET) data_offset = avio_rb32(pb);
if (flags & MOV_TRUN_FIRST_SAMPLE_FLAGS) first_sample_flags = avio_rb32(pb);
- dts = sc->track_end - sc->time_offset;
+ dts = sc->track_end + sc->time_offset;
offset = frag->base_data_offset + data_offset;
distance = 0;
av_log(c->fc, AV_LOG_TRACE, "first sample flags 0x%x\n", first_sample_flags);
@@ -3069,7 +3073,7 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
return AVERROR_EOF;
frag->implicit_offset = offset;
- st->duration = sc->track_end = dts + sc->time_offset;
+ st->duration = sc->track_end = dts - sc->time_offset;
return 0;
}
@@ -3152,6 +3156,7 @@ static int mov_read_elst(MOVContext *c, AVIOContext *pb, MOVAtom atom)
{
MOVStreamContext *sc;
int i, edit_count, version;
+ int time_offset_done = 0;
if (c->fc->nb_streams < 1)
return 0;
@@ -3175,8 +3180,17 @@ static int mov_read_elst(MOVContext *c, AVIOContext *pb, MOVAtom atom)
time = (int32_t)avio_rb32(pb); /* media time */
}
avio_rb32(pb); /* Media rate */
- if (i == 0 && time >= -1) {
- sc->time_offset = time != -1 ? time : -duration;
+ if (!time_offset_done) {
+ if (time == -1) {
+ /* delay is in movie timescale */
+ sc->time_offset_delay += duration;
+ } else if (time >= 0) {
+ /* samples to skip is in track timescale */
+ sc->time_offset_skip = time;
+ time_offset_done = 1;
+ }
+ /* timescales may not be known yet, so we can not compute
+ * a single combined time_offset yet */
}
}
--
2.9.3
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