[FFmpeg-trac] #6682(undetermined:new): hstack repeats input frames

[FFmpeg]

#6682: hstack repeats input frames
-------------------------------------+-------------------------------------
             Reporter:  damonmaria   |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  git-master   |  undetermined
             Keywords:  hstack       |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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Comment (by damonmaria):

 OK. Looking through the code for `rtpdec.c` would this be the reason my
 streams are not syncing:
 {{{
 static void finalize_packet(RTPDemuxContext *s, AVPacket *pkt, uint32_t
 timestamp)
 {
     ...
     if (s->last_rtcp_ntp_time != AV_NOPTS_VALUE && s->ic->nb_streams > 1)
 {
         ...
 }}}

 The code inside that `if` is the only place the NTP timestamp from the RTP
 stream is used. But if the `RTPDemuxContext`'s `ic` (the
 `AVFormatContext`) is not shared with the other RTSP inputs then
 `nb_streams` will be 1 (each RTSP input only has a single video stream).
 And so the multiple RTSP inputs cannot be synced with each other even tho
 they are using the same NTP timestamps.

 From here:
 https://github.com/FFmpeg/FFmpeg/blob/01718dc0df572d2f5eebd5212e93368f2b90b89a/libavformat/rtpdec.c#L583

 By employing various ffmpeg options I've managed to solve all other issues
 above except for the actual syncing of the inputs.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6682#comment:20>
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