[Live-devel] normalization of frame presentation time in live555ProxyServer

[Ross Finlayson]

> I cannot exactly understand what is the purpose of the PresentationTimeSessionNormalizer used in live555ProxyServer.

The issue here was that our RTSP *server* implementation (code) depends on the presentation times for outgoing frames (transmitted by the server) being aligned with the server's ‘wall clock’ time (in order for the server’s outgoing RTCP “Sender Reports” to be correct).

Therefore, when our ‘server’ is actually a proxy server (which takes its input from some other, ‘back-end’ server, not necessarily implemented by us), we can’t just use the presentation times that came from the ‘back-end’ server ‘as is’.  Instead, we need to adjust them so that they’re aligned with the proxy server’s ‘wall clock’ time.  That’s what “PresentationTimeSessionNormalizer” (and “PresentationTimeSubsessionNormalizer”) does.

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