scottlamb
commented
5 years ago Here's the offending ffmpeg code, in libavformat/rtpdec.c:
if (s->last_rtcp_ntp_time != AV_NOPTS_VALUE && s->ic->nb_streams > 1) {
int64_t addend;
int delta_timestamp;
/* compute pts from timestamp with received ntp_time */
delta_timestamp = timestamp - s->last_rtcp_timestamp;
/* convert to the PTS timebase */
addend = av_rescale(s->last_rtcp_ntp_time - s->first_rtcp_ntp_time,
s->st->time_base.den,
(uint64_t) s->st->time_base.num << 32);
pkt->pts = s->range_start_offset + s->rtcp_ts_offset + addend +
delta_timestamp;
return;
}
jlpoolen
There's an ffmpeg bug when a camera has audio enabled. I'll quote the troubleshooting guide below. Either we need this ffmpeg bug fixed (and the fixed version bundled with Moonfire NVR) or we need to switch RTSP libraries.
Error: pts not monotonically increasing; got 26615520 then 26539470If your streams cut out with an error message like this one, there are a couple possibilities.
One is that your camera outputs B frames. If you believe this is the case, file a feature request; Moonfire NVR currently doesn't support B frames. You may be able to configure your camera to disable B frames in the meantime.
A more subtle problem occurs in cameras such as the Dahua Starlight series when the following is true:
Moonfire NVR currently uses the ffmpeg library to talk to the cameras. ffmpeg doesn't properly support this situation. It uses the NTP time to adjust the PTS and DTS, and thus experiences jumps forward and backward. The forward jumps cause one frame to be artificially lengthened. The backward jumps create an impossible situation which causes Moonfire NVR to abort the session and retry.
In the long term, Moonfire NVR will likely implement its own RTSP support.
In the short term, you can use either of two workarounds: