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mpegtsdemux: Handle PTS/DTS wraparound with ignore-pcr=true

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The wraparound handling code assumes that the PCR gets updated regularly for
being able to detect wraparounds. With ignore-pcr=true that was not the case and
it stayed initialized at 1h forever.

To avoid this problem, update the fake PCR whenever the PTS advanced by more
than 5s, and also detect wraparounds in these fake PCRs.

Problem can be reproduced with

  $ gst-launch-1.0 videotestsrc pattern=black ! video/x-raw,framerate=1/5 ! \
    x264enc speed-preset=ultrafast tune=zerolatency ! mpegtsmux ! \
    tsdemux ignore-pcr=true ! fakesink

which restarts timestamps at 0 after around 26h30m.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7763>
This commit is contained in:
Sebastian Dröge 2024-09-30 15:51:04 +03:00 committed by GStreamer Marge Bot
parent 74cafe7b20
commit 2e4315ab5c
1 changed files with 18 additions and 4 deletions
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22
subprojects/gst-plugins-bad/gst/mpegtsdemux/mpegtspacketizer.c
View file

@ -2261,10 +2261,24 @@ mpegts_packetizer_pts_to_ts_internal (MpegTSPacketizer2 * packetizer,
PACKETIZER_GROUP_LOCK (packetizer);
pcrtable = get_pcr_table (packetizer, pcr_pid);
if (!GST_CLOCK_TIME_IS_VALID (pcrtable->base_time) && pcr_pid == 0x1fff &&
GST_CLOCK_TIME_IS_VALID (packetizer->last_in_time)) {
pcrtable->base_time = packetizer->last_in_time;
pcrtable->base_pcrtime = pts;
if (pcr_pid == 0x1fff && GST_CLOCK_TIME_IS_VALID (packetizer->last_in_time)) {
if (!GST_CLOCK_TIME_IS_VALID (pcrtable->base_time)) {
pcrtable->base_time = packetizer->last_in_time;
pcrtable->base_pcrtime = pts;
} else if (check_diff) {
/* Handle discont and wraparound */
guint64 tmp_pts = pts + pcrtable->pcroffset + packetizer->extra_shift;
if (pcrtable->base_pcrtime < tmp_pts
&& tmp_pts - pcrtable->base_pcrtime >= 5 * GST_SECOND) {
guint64 diff = tmp_pts - pcrtable->base_pcrtime - 2 * GST_SECOND;
pcrtable->base_time += diff;
pcrtable->base_pcrtime += diff;
} else if (pcrtable->base_pcrtime > tmp_pts
&& pcrtable->base_pcrtime > PCR_GST_MAX_VALUE / 2) {
pcrtable->pcroffset += PCR_GST_MAX_VALUE;
}
}
}
/* Use clock skew if present */