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ffmpeg.wasm-core
Commit 4abfa387 authored by Yusuke Nakamura's avatar Yusuke Nakamura Committed by Martin Storsjö
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mov: Change DTS-based seek into CTS-based seek. 

CTS-based seek is reasonable since player requests frames in output order
not coded order.

This change fixes seek to a keyframe within consecutive keyframes.
Let's say P[0|-1] and P[1|0], here x and y inside [x|y] are PTS and DTS
respectively, and both two frames are a keyframe. If you try to seek on
PTS=0, i.e. P[0|-1], you'll get P[1|0] if the demuxer is DTS based. This
is obviously undesirable.
Signed-off-by: 's avatarMartin Storsjö <martin@martin.st>
parent 51ca3cb6
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Inline Side-by-side
Showing with 29 additions and 15 deletions
libavformat/mov.c
View file @ 4abfa387
......@@ -2099,6 +2099,7 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
int64_t current_offset;
int64_t current_dts = 0;
unsigned int stts_index = 0;
unsigned int ctts_index = 0;
unsigned int stsc_index = 0;
unsigned int stss_index = 0;
unsigned int stps_index = 0;
......@@ -2124,6 +2125,7 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
sc->stts_count == 1 && sc->stts_data[0].duration == 1)) {
unsigned int current_sample = 0;
unsigned int stts_sample = 0;
unsigned int ctts_sample = 0;
unsigned int sample_size;
unsigned int distance = 0;
unsigned int rap_group_index = 0;
......@@ -2131,8 +2133,6 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
int rap_group_present = sc->rap_group_count && sc->rap_group;
int key_off = (sc->keyframes && sc->keyframes[0] > 0) || (sc->stps_data && sc->stps_data[0] > 0);
current_dts -= sc->dts_shift;
if (!sc->sample_count)
return;
if (sc->sample_count >= UINT_MAX / sizeof(*st->index_entries) - st->nb_index_entries)
......@@ -2180,14 +2180,15 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
if (sc->pseudo_stream_id == -1 ||
sc->stsc_data[stsc_index].id - 1 == sc->pseudo_stream_id) {
AVIndexEntry *e = &st->index_entries[st->nb_index_entries++];
int64_t current_cts = current_dts + (sc->ctts_data ? sc->ctts_data[ctts_index].duration : 0);
e->pos = current_offset;
e->timestamp = current_dts;
e->timestamp = current_cts;
e->size = sample_size;
e->min_distance = distance;
e->flags = keyframe ? AVINDEX_KEYFRAME : 0;
av_dlog(mov->fc, "AVIndex stream %d, sample %d, offset %"PRIx64", dts %"PRId64", "
av_dlog(mov->fc, "AVIndex stream %d, sample %d, offset %"PRIx64", cts %"PRId64", "
"size %d, distance %d, keyframe %d\n", st->index, current_sample,
current_offset, current_dts, sample_size, distance, keyframe);
current_offset, current_cts, sample_size, distance, keyframe);
}
current_offset += sample_size;
......@@ -2195,11 +2196,16 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
current_dts += sc->stts_data[stts_index].duration;
distance++;
stts_sample++;
ctts_sample++;
current_sample++;
if (stts_index + 1 < sc->stts_count && stts_sample == sc->stts_data[stts_index].count) {
stts_sample = 0;
stts_index++;
}
if (ctts_index + 1 < sc->ctts_count && ctts_sample == sc->ctts_data[ctts_index].count) {
ctts_sample = 0;
ctts_index++;
}
}
}
if (st->duration > 0)
......@@ -2789,13 +2795,16 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
int sample_flags = i ? frag->flags : first_sample_flags;
unsigned sample_duration = frag->duration;
int keyframe = 0;
int sample_cts = 0;
int64_t cts;
if (flags & MOV_TRUN_SAMPLE_DURATION) sample_duration = avio_rb32(pb);
if (flags & MOV_TRUN_SAMPLE_SIZE) sample_size = avio_rb32(pb);
if (flags & MOV_TRUN_SAMPLE_FLAGS) sample_flags = avio_rb32(pb);
sc->ctts_data[sc->ctts_count].count = 1;
sc->ctts_data[sc->ctts_count].duration = (flags & MOV_TRUN_SAMPLE_CTS) ?
avio_rb32(pb) : 0;
if (flags & MOV_TRUN_SAMPLE_CTS) sample_cts = avio_rb32(pb);
sc->ctts_data[sc->ctts_count].count = 1;
sc->ctts_data[sc->ctts_count].duration = sample_cts;
cts = dts + sample_cts;
sc->ctts_count++;
if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
keyframe = 1;
......@@ -2805,11 +2814,11 @@ static int mov_read_trun(MOVContext *c, AVIOContext *pb, MOVAtom atom)
MOV_FRAG_SAMPLE_FLAG_DEPENDS_YES));
if (keyframe)
distance = 0;
av_add_index_entry(st, offset, dts, sample_size, distance,
av_add_index_entry(st, offset, cts, sample_size, distance,
keyframe ? AVINDEX_KEYFRAME : 0);
av_dlog(c->fc, "AVIndex stream %d, sample %d, offset %"PRIx64", dts %"PRId64", "
av_dlog(c->fc, "AVIndex stream %d, sample %d, offset %"PRIx64", cts %"PRId64", "
"size %d, distance %d, keyframe %d\n", st->index, sc->sample_count+i,
offset, dts, sample_size, distance, keyframe);
offset, cts, sample_size, distance, keyframe);
distance++;
dts += sample_duration;
offset += sample_size;
......@@ -3335,7 +3344,12 @@ static AVIndexEntry *mov_find_next_sample(AVFormatContext *s, AVStream **st)
MOVStreamContext *msc = avst->priv_data;
if (msc->pb && msc->current_sample < avst->nb_index_entries) {
AVIndexEntry *current_sample = &avst->index_entries[msc->current_sample];
int64_t dts = av_rescale(current_sample->timestamp, AV_TIME_BASE, msc->time_scale);
int64_t dts;
if (msc->ctts_data)
dts = av_rescale(current_sample->timestamp - msc->dts_shift - msc->ctts_data[msc->ctts_index].duration,
AV_TIME_BASE, msc->time_scale);
else
dts = av_rescale(current_sample->timestamp, AV_TIME_BASE, msc->time_scale);
av_dlog(s, "stream %d, sample %d, dts %"PRId64"\n", i, msc->current_sample, dts);
if (!sample || (!s->pb->seekable && current_sample->pos < sample->pos) ||
(s->pb->seekable &&
......@@ -3409,9 +3423,9 @@ static int mov_read_packet(AVFormatContext *s, AVPacket *pkt)
}
pkt->stream_index = sc->ffindex;
pkt->dts = sample->timestamp;
pkt->pts = sample->timestamp;
if (sc->ctts_data && sc->ctts_index < sc->ctts_count) {
pkt->pts = pkt->dts + sc->dts_shift + sc->ctts_data[sc->ctts_index].duration;
pkt->dts = pkt->pts - sc->dts_shift - sc->ctts_data[sc->ctts_index].duration;
/* update ctts context */
sc->ctts_sample++;
if (sc->ctts_index < sc->ctts_count &&
......@@ -3424,8 +3438,8 @@ static int mov_read_packet(AVFormatContext *s, AVPacket *pkt)
} else {
int64_t next_dts = (sc->current_sample < st->nb_index_entries) ?
st->index_entries[sc->current_sample].timestamp : st->duration;
pkt->dts = pkt->pts;
pkt->duration = next_dts - pkt->dts;
pkt->pts = pkt->dts;
}
if (st->discard == AVDISCARD_ALL)
goto retry;
......
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