[Live-devel] UDP packets appear to be empty, forcing switch to TCP in VLC

[Dave McMordie]

Okay, I think I have made some progress.  I found two issues:


   1. In-line with your firewall hypothesis, the server was announcing a
   169.254.X.Y address, but I was playing from rtsp://127.0.0.1:5640/.
   When I pointed my rtsp URL to 169.254.X.Y instead of 127.0.0.1, the UDP
   packets started arriving and both openRTSP and VLC can play the stream
   after a couple seconds of buffering. We were getting the datagrams, but
   code inside GroupSock.cpp line 314 was checking that the address matched
   the advertised address, and returning with bytesRead still equal to zero,
   despite a successful read.  If other readers this works-on-TCP-but-not-UDP
   issue, I suggest looking at whether datagrams are arriving in this layer or
   one level up in RTPInterface.cpp.
   2. After digging some more into the framing issue, it became clear that
   the code I was using to split the stream into discrete NALs was not working
   properly.  The clue was that I was seeing frame lengths of > 1000 bytes in
   the saveCopyOfSPS() method.  Since the SPS is typically less than a dozen
   bytes, this was crazy.  It might be worth erroring out in there to keep
   other users from doing something so bone-headed.

QuickTime still does not play the stream and neither does the flash player
that I need to get working (
https://github.com/AxisCommunications/locomote-video-player).  However,
with the change to the framing, the flash player now appears to get much
further along.  I know neither of these are anything to do with you, but if
you think QuickTime *should* work, please let me know as it suggests there
are other bugs in my server instance (possibly still to do with framing).

ffprobe complains that the VUI is truncated.  Not sure if or how to chase
this down, but I certainly welcome any other suggestions for validating
that by SDP and stream are 100% compliant.

Thanks again,

Dave
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