[FFmpeg-devel] How ffplay resolves bad timestamps?
Wed Dec 22 12:42:07 CET 2010
I've got some unfinished code for emitting timestamps from the beginning,
> if the server sends the start RTP timestamp with a RTP-Info header in
> response to the PLAY request. Do your servers send RTP-Info headers?
Yes, for example:
PLAY rtsp://192.168.253.153/ch0_unicast_firststream/ RTSP/1.0
RTSP/1.0 200 OK
Date: Wed, Dec 22 2010 10:32:24 GMT
if you provide me with the patch, I will be happy to test it.
> I guess the RTSP demuxer could output some kind of timestamp from the very
> beginning, too, (by setting the first received packet to pts=0 in each
> stream), but that might also result in non-monotone timestamps for some
> streams once they're synced properly at the first RTCP packet. (On the
> other hand, there's always the risk for non-monotone timestamps whenever
> the sync is adjusted when a RTCP packet is received, regardless of which
> way the initial sync is achieved.)
As majority of servers (in my experience at least) send the RTP-Info header,
I think that using it should cover most of cases out there. The minority
left, might handled via the method I do (i.e. dropping anything up to first
good key-frame timestamp).
Recovering from non-monotone is quite difficult, and I think that adding
more possible causes is not an optimal solution :).
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