[FFmpeg-devel] Timestamp issues in live RTP->mpegts bridges

Alexandre Ferrieux alexandre.ferrieux
Mon Jan 19 16:39:27 CET 2009


Thanks to your help guys, I'm now receiving live H263/RTP flow from a 
mobile phone and the result can be converted to whatever output codec 
and encapsulation is wanted. Fine !

Now, I still have a small issue with the timing of the produced output:

If I instruct to transcode to mpeg2video encapsulated in mpegts, and 
save this to a flat ".ts" file, then when playing back the file (with 
mplayer or ffplay) I see it is playing at 30fps, regardless of the input 
fps which is 15fps. So it is twice too fast in that case. If instead of 
writing to a file I send over UDP, I see bursts of images (of course) 
because of this time scale mismatch...

Question: how are the input RTP stamps supposed to reach the other end ? 
I'm ready to add some code to rtpdec.c or to my H263-specific dynamic 
depayloader, but I just need a bit of guidance.



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