[Live-devel] RTP timestamp vs presentation timestamp in MPEG2 elementary streams

[Florian Winter]

hi

this is a general question about MPEG2 and RTP. sorry for offtopic, but 
perhaps someone on this
mailing list can help.

the RFC says that the RTP timestamp of an MPEG2 RTP packet is *not* the 
presentation timestamp (PTS)
of the contained video frame, but the transmission time of the first 
byte of the packet.
further on the RFC seems to contradict itself by stating that the 
timestamp field of the fixed RTP header
carries the presentation time (PTS). did I misinterpreted the RFC here?

also, since MPEG2 elementary streams are directly encapsulated into RTP 
packets, they contain the actual
presentation timestamps as well, and these may be different from the RTP 
timestamps. is this correct?
(it is then the job of the video decoder on the receiver side to parse 
the presentation timestamp in the MPEG2
elementary stream, whereas the RTP timestamp is not used by the 
receiving application).

i tried to find answers with google, but only found the RFC, which 
started the confusion ;)
thanks in advance for any help

fw