sysutils/ffmpeg
1
0
Fork 0
mirror of https://git.ffmpeg.org/ffmpeg.git synced 2026-10-24 02:09:03 +03:00
Code Activity

avformat/hls: rebase seek discard threshold to each playlist's DTS baseline

Browse Source 
After a seek, hls_read_packet drops packets until each playlist reaches
seek_timestamp. That threshold lives on c->first_timestamp's baseline,
i.e. the DTS of whichever stream produced the very first packet. Streams
can have different DTS baselines though. So comparing one stream's
threshold against another stream's DTS is wrong. A stream whose first
keyframe precedes the global baseline gets its segment keyframe dropped
and resumes a segment (or more) late.

Track the first DTS per playlist and rebase the threshold onto each
playlist's own baseline. Since HLS segments are presentation-aligned
across renditions, every stream then resumes at the same presentation
time. seek_timestamp keeps its meaning on the global timeline, only the
per-playlist comparison value is translated.

This fixes playlists that would be unable to play from the start, and
instead skip one or more segments, before data is output.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
This commit is contained in:
Kacper Michajłow
2026-06-17 07:00:42 +02:00
parent caa3fa6af0
commit e27ad5760c
2 changed files with 41 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

44
libavformat/hls.c
View File

@@ -159,6 +159,9 @@ struct playlist {
HLSAudioSetupInfo audio_setup_info;
/* Constant offset of this playlist's DTS baseline relative to
* c->first_timestamp. */
int64_t ts_offset;
int64_t seek_timestamp;
int seek_flags;
int seek_stream_index; /* into subdemuxer stream array */
@@ -349,6 +352,7 @@ static struct playlist *new_playlist(HLSContext *c, const char *url,
return NULL;
}
av_strlcpy(pls->url, abs_url, sizeof(pls->url));
pls->ts_offset = AV_NOPTS_VALUE;
pls->seek_timestamp = AV_NOPTS_VALUE;
pls->is_id3_timestamped = -1;
@@ -2582,7 +2586,8 @@ static int recheck_discard_flags(AVFormatContext *s, int first)
pls->pb.pub.eof_reached = 0;
if (c->cur_timestamp != AV_NOPTS_VALUE) {
/* catch up */
pls->seek_timestamp = c->cur_timestamp;
pls->seek_timestamp = c->cur_timestamp +
(pls->ts_offset != AV_NOPTS_VALUE ? pls->ts_offset : 0);
pls->seek_flags = AVSEEK_FLAG_ANY;
pls->seek_stream_index = -1;
}
@@ -2700,24 +2705,29 @@ static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
fill_timing_for_id3_timestamped_stream(pls);
}
if (c->first_timestamp == AV_NOPTS_VALUE &&
pls->pkt->dts != AV_NOPTS_VALUE) {
if (pls->ts_offset == AV_NOPTS_VALUE &&
pls->pkt->dts != AV_NOPTS_VALUE) {
int64_t seg_idx = pls->cur_seq_no - pls->start_seq_no;
c->first_timestamp = av_rescale_q(pls->pkt->dts,
int64_t ts = av_rescale_q(pls->pkt->dts,
get_timebase(pls), AV_TIME_BASE_Q);
/* EVENT playlists preserve all segments from the start */
if (pls->type == PLS_TYPE_EVENT) {
if (pls->type == PLS_TYPE_EVENT)
for (int64_t k = 0; k < seg_idx && k < pls->n_segments; k++)
c->first_timestamp -= pls->segments[k]->duration;
ts -= pls->segments[k]->duration;
for (unsigned k = 0; k < s->nb_streams; k++) {
AVStream *st = s->streams[k];
if (st->start_time == AV_NOPTS_VALUE)
st->start_time = av_rescale_q(c->first_timestamp,
AV_TIME_BASE_Q, st->time_base);
}
if (c->first_timestamp == AV_NOPTS_VALUE) {
c->first_timestamp = ts;
if (pls->type == PLS_TYPE_EVENT)
for (unsigned k = 0; k < s->nb_streams; k++) {
AVStream *st = s->streams[k];
if (st->start_time == AV_NOPTS_VALUE)
st->start_time = av_rescale_q(ts,
AV_TIME_BASE_Q, st->time_base);
}
}
pls->ts_offset = ts - c->first_timestamp;
}
}
@@ -2934,7 +2944,15 @@ static int hls_read_seek(AVFormatContext *s, int stream_index,
/* Reset the init segment so it's re-fetched and served appropriately */
pls->cur_init_section = NULL;
pls->seek_timestamp = seek_timestamp;
/* The discard in hls_read_packet compares this playlist's packet DTS
* against seek_timestamp, but seek_timestamp is on c->first_timestamp's
* baseline (whichever stream produced the first packet). Streams can
* have different DTS baselines, so translate the threshold onto this
* playlist's own baseline using its captured offset. */
if (pls->ts_offset != AV_NOPTS_VALUE)
pls->seek_timestamp = seek_timestamp + pls->ts_offset;
else
pls->seek_timestamp = seek_timestamp;
pls->seek_flags = flags;
if (pls != seek_pls) {

20
tests/ref/seek/hls
View File

@@ -2,19 +2,19 @@ ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st:-1 flags:0 ts:-1.000000
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st:-1 flags:1 ts:-0.105833
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 0 flags:0 ts: 0.788333
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 0 flags:1 ts: 1.682500
ret: 0 st: 0 flags:1 dts: 1.698078 pts: 1.698078 pos: 11092 size: 1253
ret: 0 st: 1 flags:0 dts: 1.600000 pts: 1.600000 pos: 8836 size: 2330
ret: 0 st: 1 flags:0 ts: 2.576667
ret: 0 st: 0 flags:1 dts: 2.586233 pts: 2.586233 pos: 55836 size: 1254
ret: 0 st: 1 flags:1 ts: 3.470833
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st:-1 flags:0 ts: 4.365002
ret: 0 st: 0 flags:1 dts: 4.388689 pts: 4.388689 pos: 45308 size: 1254
ret: 0 st:-1 flags:1 ts:-0.740831
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 0 flags:0 ts: 0.153333
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 0 flags:1 ts: 1.047500
@@ -22,7 +22,7 @@ ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 1 flags:0 ts: 1.941667
ret: 0 st: 0 flags:1 dts: 1.959300 pts: 1.959300 pos: 24252 size: 1254
ret: 0 st: 1 flags:1 ts: 2.835833
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st:-1 flags:0 ts: 3.730004
ret: 0 st: 0 flags:1 dts: 3.735622 pts: 3.735622 pos: -1 size: 1254
ret: 0 st:-1 flags:1 ts: 4.624171
@@ -34,20 +34,20 @@ ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 1 flags:0 ts: 1.306667
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 1 flags:1 ts: 2.200844
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st:-1 flags:0 ts: 3.095006
ret: 0 st: 0 flags:1 dts: 3.108689 pts: 3.108689 pos: 82156 size: 1254
ret: 0 st:-1 flags:1 ts: 3.989173
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 0 flags:0 ts: 4.883344
ret: 0 st: 0 flags:1 dts: 4.885011 pts: 4.885011 pos: -1 size: 1253
ret: 0 st: 1 flags:0 dts: 4.800000 pts: 5.100000 pos: 20492 size: 3860
ret: 0 st: 0 flags:1 ts:-0.222489
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 1 flags:0 ts: 0.671678
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st: 1 flags:1 ts: 1.565844
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913
ret: 0 st:-1 flags:0 ts: 2.460008
ret: 0 st: 0 flags:1 dts: 2.481744 pts: 2.481744 pos: 50572 size: 1254
ret: 0 st:-1 flags:1 ts: 3.354175
ret: 0 st: 0 flags:1 dts: 1.515211 pts: 1.515211 pos: -1 size: 1254
ret: 0 st: 1 flags:1 dts: 1.400000 pts: 1.500000 pos: 564 size: 3913