[Live-devel] RTCP SR clock sync diff

[Mike Frantzen]

I had a problem when using VLC to transcode from an AXIS camera into an RTP
stream. In the RTCP Sender Report the AXIS camera is deriving its NTP time
from the monotonic uptime instead of the wall clock. Then it converts it
from unix epoch time into NTP time.

The real issue is that VLC/live555 start issuing timestamps based on the
local wall clock.  Then several seconds later the RTCP SR includes a
timestamp which significantly alters the timestamps in the name of
synchronization.  Then VLC starts rejecting the new timestamps since they
appear to be in the past.

The attached diff will only synchronize the timestamp if: the timestamp has
never been set; or the sender's and receiver's clocks appear to be on the
same time reference. It determines the latter if they are less than five
seconds apart.

.mike
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