[Live-devel] Request to Fix inconsistent timestamps in openrtsp

[Keith Page]

We currently use live555 as a module for vlc to record two camera 
streams and one audio onto a mosaic canvas. All media sources are ntp 
synced so the time stamps coming are in lock step, our video streams are 
able to stay in perfect sync, our audio however is always off by 4 - 8 
seconds.

The beginning of the muxing in vlc suffers from starts and stops while 
RTCP occurs. The time stamps being fed into vlc from openRTSP starts as 
actual unix time stamps, once a RTCP is received from the media source 
openRTSP changes to an arbitrarily number, this inconsistency ( going 
from normal unix epoch time stamp to a random one )  causes vlc to reset 
it's PTS gap and it throw out frames until it detect the problem and 
reset its PTS gap.

I read somewhere in the forums that this was a known issue and a better 
way would be for openRTSP to pick an arbitrary seed for all streams at 
start and determine a proper offset for each stream from that one seed. 
This would ensure we're counting in a consistent fashion from the 
initial setup and through the first RCTP sync from the media source.

It's my understanding that by fixing this here in openRTSP this will fix 
our problem in vlc and will create a better library for other media 
players using openRTSP. I could very well be mistaken. However if upon 
review of our problem and what we're trying to accomplish this proves to 
be correct our company would pay to have this fixed properly for the 
benefit of everyone.

Our goal is to end up with a library that allows us to take these two 
video streams and one audio stream, which are all time stamped properly 
themselves and have them stay in sync after the mux.

Please let me know if you have any further questions and if you can help.
Keith