[vlc-devel] RTP stream packet loss error recovery

John Zavgren john at zavgren.com
Thu Jan 26 15:56:56 CET 2012


I have a situation where a received RTP stream hangs when a packet is lost.
(See the "clipping" that follows this note.) The transmitter keeps
ratcheting forward in sequence number space, but the receive processing, in
the live555 RTP plugin, waits for a missing packet, indefinitely... And, it
never arrives... And, the video decoding is frozen. Frame resequencing
seems to work flawlessly, but a packet loss event seems "fatal".

Where is the packet loss error recovery mechanism?

I assume there must be a "watch dog" timer somewhere that will cause the
RTP receive processing to give up on the lost frame and move forward.

John Zavgren

------ previous posting ---------

I'm using the live555 RTP plugin in VLC. I'm feeding an RTP stream to it
(generated by an RTSP session) that is being carried via multiple CDMA data
cards... each network path has unknown and changing delay
characteristics... packets arrive out of order, and sometimes they are lost.

I instrumented the RTP code so that it tells me the history of the RTP
sequence numbers at the receiver.

It appears that whenever a packet is lost, the receive "hangs"...
presumably because it's patiently waiting for an arrival that will never

I refuse to believe that corporations are actually people until the state
of Texas executes one.

John Zavgren
603-371-0513 (home)
603-801-2094 (cell)
johnzavgren (skype)
603-821-0904 (skype)
john at zavgren.com
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