[FFmpeg-user] h264_omx and non-existing PPS 0 referenced

[luke]

To clarify, ffplay does display any image, it just keep outputting the error message regarding missing PPS.

I had a look and someone mentioned -force_key_frames on video.stackexchange.com.


I tried this:


    ./ffmpeg -i /dev/video0 -c:v h264_omx -force_key_frames 'expr:gte(t,n_forced)' -f rtp rtp://192.168.0.101:1234


But ffplay is still not able to display anything if not started first.

If I dump the output into a file, I see that intermediate frames are generated:


  ./ffmpeg -i /dev/video0 -c:v h264_omx -force_key_frames 'expr:gte(t,n_forced)' -o file.avi

  ./ffprobe -i file.avi -select_streams v -show_frames -of csv -show_entries frame=pict_type

frame,I
frame,P
frame,P
frame,P
frame,P
frame,P
frame,P
frame,P
frame,P
frame,P
frame,P
frame,P
frame,I
frame,P
frame,P
frame,P

[...]


So why would ffplay not able to decode those frame? Is this a limitation of the rdp protocol somehow.


________________________________
De : ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> de la part de luke <skywal_l at hotmail.com>
Envoyé : jeudi 2 mars 2017 19:17
À : ffmpeg-user at ffmpeg.org
Objet : [FFmpeg-user] h264_omx and non-existing PPS 0 referenced

Trying to stream a webcam through rtp with a raspberry pi.


Cating the SDP file on my desktop, and launching ffplay:


    ffplay sdp.out



then streaming out this way:


    ffmpeg -i /dev/video0 -c:v h264_omx -f rtp rtp://192.168.0.101:1234



works perfectly. But If I launch ffmpeg first THEN ffplay, ffplay stutters some error message about missing PPS:

[h264 @ 0x7fd97c0008c0] decode_slice_header error
[h264 @ 0x7fd97c0008c0] no frame!
[h264 @ 0x7fd97c0008c0] non-existing PPS 0 referenced


After looking for a while I understand some intermediary frame might be missing. However, using the -g option this way does not change anything:


    ffmpeg -i /dev/video0 -c:v h264_omx -g 30 -f rtp rtp://192.168.0.101:1234


It is a problem for me because I am using the raspberry as a securiy camera. My desktop can be restarted from time to time and I need ffplay to be able to catch long after streaming is started.


Any help is appreciated.

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