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fix: handle AV_NOPTS_VALUE pts/dts in VideoStore 

Some cameras produce packets where both pts and dts are AV_NOPTS_VALUE.
Previously, video passthrough skipped timestamp processing for these,
write_packet set dts to -1 and never updated tracking state,
audio_first_dts could be set to AV_NOPTS_VALUE permanently, and the
reorder queue compared AV_NOPTS_VALUE values meaninglessly.

- Video passthrough: synthesize dts as last_dts+1 when both pts/dts
  are undefined, keeping monotonic ordering without colliding with the
  next valid packet's timestamp
- Audio: guard audio_first_dts from being set to AV_NOPTS_VALUE, and
  guard passthrough subtraction to avoid NOPTS arithmetic overflow
- write_packet: synthesize dts as last_dts+1 instead of reusing stale
  last_dts, fall back to 0 when no history exists, and always update
  tracking state (last_dts/next_dts/last_duration) regardless of
  which branch was taken
- Reorder queue: skip reordering when incoming dts is undefined and
  treat queued NOPTS packets as in-order

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
pull/4639/head^2
Isaac Connor 2026-02-23 17:55:18 -05:00
parent 635439eb5b
commit ce5fb82f08
1 changed files with 38 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
src/zm_videostore.cpp
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@ -1086,17 +1086,20 @@ int VideoStore::writePacket(const std::shared_ptr<ZMPacket> zm_pkt) {
bool have_out_of_order = false;
auto rit = queue.rbegin();
// Find the previous packet for the stream, and check dts
while (rit != queue.rend()) {
AVPacket *p = ((*rit)->packet).get();
if (p->dts <= av_pkt->dts) {
Debug(1, "Found in order packet");
// packets are in order, everything is fine
break;
} else {
have_out_of_order = true;
}
rit++;
} // end while
// Skip reordering when incoming dts is undefined — can't compare meaningfully
if (av_pkt->dts != AV_NOPTS_VALUE) {
while (rit != queue.rend()) {
AVPacket *p = ((*rit)->packet).get();
if (p->dts == AV_NOPTS_VALUE || p->dts <= av_pkt->dts) {
Debug(1, "Found in order packet");
// packets are in order, everything is fine
break;
} else {
have_out_of_order = true;
}
rit++;
} // end while
}
if (have_out_of_order) {
if (rit == queue.rend()) {
@ -1364,6 +1367,15 @@ int VideoStore::writeVideoFramePacket(const std::shared_ptr<ZMPacket> zm_packet)
}
if ((ipkt->pts != AV_NOPTS_VALUE) and (ipkt->dts != AV_NOPTS_VALUE)) {
av_packet_rescale_ts(opkt.get(), video_in_stream->time_base, video_out_stream->time_base);
} else if ((ipkt->pts == AV_NOPTS_VALUE) and (ipkt->dts == AV_NOPTS_VALUE)) {
// Both undefined — use last_dts+1 as minimal monotonic increment
if (last_dts[video_out_stream->index] != AV_NOPTS_VALUE) {
opkt->dts = last_dts[video_out_stream->index] + 1;
} else {
opkt->dts = 0;
}
opkt->pts = opkt->dts;
Debug(2, "No pts/dts, synthesized dts %" PRId64 " from last_dts", opkt->dts);
}
} // end if wallclock or not
write_packet(opkt.get(), video_out_stream);
@ -1384,7 +1396,7 @@ int VideoStore::writeAudioFramePacket(const std::shared_ptr<ZMPacket> zm_packet)
ipkt->dts, ts, FPSeconds(zm_packet->timestamp.time_since_epoch()).count());
}
if (audio_first_dts == AV_NOPTS_VALUE) {
if (audio_first_dts == AV_NOPTS_VALUE && ipkt->dts != AV_NOPTS_VALUE) {
audio_first_dts = ipkt->dts;
audio_next_pts = audio_out_ctx->frame_size;
Debug(3, "audio first_dts to %" PRId64, audio_first_dts);
@ -1441,8 +1453,8 @@ int VideoStore::writeAudioFramePacket(const std::shared_ptr<ZMPacket> zm_packet)
opkt->flags = ipkt->flags;
opkt->duration = ipkt->duration;
if (audio_first_dts != AV_NOPTS_VALUE) {
opkt->pts = ipkt->pts - audio_first_dts;
opkt->dts = ipkt->dts - audio_first_dts;
opkt->pts = (ipkt->pts != AV_NOPTS_VALUE) ? ipkt->pts - audio_first_dts : AV_NOPTS_VALUE;
opkt->dts = (ipkt->dts != AV_NOPTS_VALUE) ? ipkt->dts - audio_first_dts : AV_NOPTS_VALUE;
} else {
opkt->pts = ipkt->pts;
opkt->dts = ipkt->dts;
@ -1465,11 +1477,14 @@ int VideoStore::write_packet(AVPacket *pkt, AVStream *stream) {
ZM_DUMP_PACKET(pkt, "packet in write_packet");
if (pkt->dts == AV_NOPTS_VALUE) {
Debug(1, "undef dts, fixing by setting to stream last_dts %" PRId64, last_dts[stream->index]);
if (last_dts[stream->index] == AV_NOPTS_VALUE) {
last_dts[stream->index] = -1;
}
pkt->dts = last_dts[stream->index];
if (last_dts[stream->index] != AV_NOPTS_VALUE) {
pkt->dts = last_dts[stream->index] + 1;
Debug(1, "undef dts, synthesized %" PRId64 " from last_dts %" PRId64 " + 1",
pkt->dts, last_dts[stream->index]);
} else {
pkt->dts = 0;
Debug(1, "undef dts and no last_dts, setting to 0");
}
} else {
if (last_dts[stream->index] != AV_NOPTS_VALUE) {
if (pkt->dts < last_dts[stream->index]) {
@ -1486,10 +1501,11 @@ int VideoStore::write_packet(AVPacket *pkt, AVStream *stream) {
if (pkt->dts > pkt->pts) pkt->pts = pkt->dts; // Do it here to avoid warning below
}
}
next_dts[stream->index] = pkt->dts + pkt->duration;
last_dts[stream->index] = pkt->dts;
last_duration[stream->index] = pkt->duration;
}
// Always update tracking now that dts has a valid value
next_dts[stream->index] = pkt->dts + pkt->duration;
last_dts[stream->index] = pkt->dts;
last_duration[stream->index] = pkt->duration;
if (pkt->pts == AV_NOPTS_VALUE) {
pkt->pts = pkt->dts;