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avformat/mux: Peek into the muxing queue for avoid_negative_ts 

Peeking into the muxing queue can improve the estimate of
the lowest timestamp needed for avoid_negative_ts in case
the lowest timestamp is in a packet other than the first packet
to be muxed.
This fixes tickets #4536 and #5784 as well as the output from
the matroska-avoid-negative-ts FATE-test.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2022-01-18 22:55:27 +01:00
parent c602deb138
commit c24ee7c275
4 changed files with 21 additions and 6 deletions
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2
libavformat/avformat.h
View File

@ -1527,7 +1527,7 @@ typedef struct AVFormatContext {
/**
* Avoid negative timestamps during muxing.
* Any value of the AVFMT_AVOID_NEG_TS_* constants.
* Note, this only works when using av_interleaved_write_frame. (interleave_packet_per_dts is in use)
* Note, this works better when using av_interleaved_write_frame().
* - muxing: Set by user
* - demuxing: unused
*/

21
libavformat/mux.c
View File

@ -655,16 +655,33 @@ static void handle_avoid_negative_ts(FFFormatContext *si, FFStream *sti,
if (si->avoid_negative_ts_status == AVOID_NEGATIVE_TS_UNKNOWN) {
int use_pts = si->avoid_negative_ts_use_pts;
int64_t ts = use_pts ? pkt->pts : pkt->dts;
AVRational tb = sti->pub.time_base;
if (ts == AV_NOPTS_VALUE)
return;
/* Peek into the muxing queue to improve our estimate
* of the lowest timestamp if av_interleaved_write_frame() is used. */
for (const PacketListEntry *pktl = si->packet_buffer.head;
pktl; pktl = pktl->next) {
AVRational cmp_tb = s->streams[pktl->pkt.stream_index]->time_base;
int64_t cmp_ts = use_pts ? pktl->pkt.pts : pktl->pkt.dts;
if (cmp_ts == AV_NOPTS_VALUE)
continue;
if (s->output_ts_offset)
cmp_ts += av_rescale_q(s->output_ts_offset, AV_TIME_BASE_Q, cmp_tb);
if (av_compare_ts(cmp_ts, cmp_tb, ts, tb) < 0) {
ts = cmp_ts;
tb = cmp_tb;
}
}
if (ts < 0 ||
ts > 0 && s->avoid_negative_ts == AVFMT_AVOID_NEG_TS_MAKE_ZERO) {
for (unsigned i = 0; i < s->nb_streams; i++) {
AVStream *const st2 = s->streams[i];
FFStream *const sti2 = ffstream(st2);
sti2->mux_ts_offset = av_rescale_q_rnd(-ts,
sti->pub.time_base,
sti2->mux_ts_offset = av_rescale_q_rnd(-ts, tb,
st2->time_base,
AV_ROUND_UP);
}

2
tests/fate/matroska.mak
View File

@ -101,8 +101,6 @@ fate-matroska-dovi-write-config8: CMD = transcode mov $(TARGET_SAMPLES)/hevc/dv8
# the first packet (with the overall lowest dts) is a video packet,
# whereas an audio packet to be muxed later has the overall lowest pts
# which happens to be negative and therefore needs to be shifted.
# This is currently buggy (the timestamps are not shifted properly:
# the first audio packet has negative pts).
# (-ss 1.09 ensures that a video frame has the lowest dts of all packets;
# yet there is an audio packet with the overall lowest pts. output_ts_offset
# makes the pts of the audio packet, but not the leading video packet negative

2
tests/ref/fate/matroska-avoid-negative-ts
View File

@ -1,4 +1,4 @@
90cf5a330659140d47ec11208f525908 *tests/data/fate/matroska-avoid-negative-ts.matroska
804842437b2be0a1604ce33c6b08c800 *tests/data/fate/matroska-avoid-negative-ts.matroska
973070 tests/data/fate/matroska-avoid-negative-ts.matroska
#extradata 0: 22, 0x2885037c
#tb 0: 1/1000