[Live-devel] RTP timestamp issue after RTCP synchronization

[Ross Finlayson]

> I’m still searching why RTCP create this gap.  The issue is not the timestamp gap in one stream, but the difference between the synchronized timestamps of the two streams.
> The issue can be reproduced with an unmodified “live555ProxyServer”.

For RTCP-based a/v synchronization to work properly for streams that are sent by the LIVE555 RTSP server implementation, two things have to be true:
1/ The presentation times for each frame have to be accurate (obviously), and
2/ The presentation times have to be aligned with 'wall-clock' time - i.e., times that would be generated by calling "gettimeofday()".

This is also true for the proxy server (because it has a RTSP server inside it).

So I think you have exposed a deficiency (bug) in the proxy server code - it is not ensuring that conditions 1/ and 2/ are true when it retransmits (i.e., relays) incoming frames.  This is something that I'll need to fix.

(Out of curiosity, does VLC play the stream OK (i.e., without any a/v sync problems) if you try playing it directly from the network camera (i.e., not through a proxy)?)


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/

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