[FFmpeg-devel] Additional RTSP issues
Tue Jul 14 17:45:13 CEST 2009
Stas Oskin wrote:
> In addition to the SEQ problem that I'm working on right now, I have other 2
> issues which I might be able to tinker:
> 1) There is a delay between the moment initial connection to RTSP is done
> ,and before the read__packet() returns the first packet. The delay is about
> 2-3 seconds, and then all the packets for these seconds are returned at once
> (one after another), with AV_NOPTS_VALUE for their PTS/DTS value.
This should only happen if you receive a stream that has been started before
the player (basically, you cannot receive reliable timestamps until the first
RTCP SR packet has been received).
> Other RTSP implementation don't seem to have this issue.
Some players return fake timestamps until the first RTCP SR packet is received
(for example, if receiving a multicast stream with "vlc file.sdp" you can see
a discontinuity in the audio or in the video after few seconds).
> Any idea if it's as intended, and there any setting which controls it? If
> not, is it a know issue, which can be solved?
If you are playing an "rtsp://" URL, ensure that the server sends an RTCP SR
packet as soon as the player starts playing the stream.
> 2) It seems that current RTSP implementation doesn't send keep-alive signals
Not sure what a "keep-alive" signal is... Where is it described in the standard?
For sure, the RTCP RR packets sent by libavformat contain unreliable information,
but this seems to be by design.
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