[Live-devel] RTT Calculation (clarification)

Dixon Siu dixonsiu at mediaglue.co.jp
Thu Apr 15 11:17:48 PDT 2004

Hi Ross and Cavalera,

RTT is indeed round trip time. I want to use RTCP to provide the RTT. So I
saw that in the file "RTPSink.cpp" in liveMedia folder, the procedure
noteIncomingRR does print out the estimated RTT (the calculation is
according to the suggestion from RFC3550). So I assume the result is
correct. And I don't want to use ping because my application should simply
get the RTT from RTCP Receiver Reports and then dynamically adjusts the
streaming bit rate.

The funny thing is that if my receiver uses Windows Media Player, the RTT is
correct. It only provides wrong RTT when the receiver uses Quick Time Player
to view the RTSP stream. Moreover, when Quick Time Player is used, the
streaming server usually prompts for unrecognisable RTCP packet. So I was
wondering if Quick Time Player sent non-standard RR.

Anyway, my receivers will always use Windows Media Player to view the
stream. So I should have no problem.


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