Sorry, I should have been more clear in my question...
I'm specifically trying to work out how to create the "RTP-Info" header
in a RTSP/PLAY-Response.
It looks quite simple. Grab the RTP-Time & SeqNum of the first RTP
packet sent on each stream to the client, format it correctly and we're
done. Unfortunately, this causes low-powered clients (like cell-phones)
to have terrible A/V sync.
If you look at the example I posted below, the first RTP packets going
to the client for each stream (packets 922 & 926) have details like
this:
922: RTP/3456 to CLIENT
Seq: 39932
RTP: 383841717
926: RTP/3458 to CLIENT
Seq: 59095
RTP: 671369087
But the RTSP/PLAY-Response looks like this:
925: RTSP/PLAY-Response to CLIENT
RTP-Info:
url=rtsp://172.28.15.239/rtpencoder/Blah.sdp/streamid=1;seq=39932;rtptim
e=383841717,
url=rtsp://172.28.15.239/rtpencoder/Blah.sdp/streamid=0;seq=59095;rtptim
e=671239890
There is a delta of -129197 in the RTP-Time specified in the "RTP-Info"
header and the RTP-Time in the packet with SeqNum==59095. How is this
delta calculated? Anyone know?
Cheers,
ChrisB
Chris Burns
M: +64 21 391 286
[EMAIL PROTECTED]
Sent: Thursday, 07 August 2008 22:32
To: [EMAIL PROTECTED]
Subject: [Live-devel] Calculating rtptime for RTSP/PLAY-Response
"RTP-Info"header
Hi all,
I'm trying to figure out how to calculate the RTPTime values in
the RTSP/PLAY-Response "RTP-Info" header, based on an incoming live
RTP/RTCP stream(s) from a live encoder.
I've pulled apart an HUSM packet dump and the critical section
looks something like this:
769: RTCP-SR/9301 from LENC
NTP: MSW: 3403825895 (0xcae242e7); LSW: 133143986
(0x07ef9db2) ==> Nov 12, 2007 03:11:35.0310 UTC
RTP: 670943030
803: RTCP-SR/9303 from LENC
NTP: MSW: 3403825896 (0xcae242e8); LSW: 64424509
(0x03d70a3d) ==> Nov 12, 2007 03:11:36.0150 UTC
RTP: 383790848
840: RTCP-SR/9301 from LENC
NTP: MSW: 3403825897 (0xcae242e9); LSW: 64424509
(0x03d70a3d) ==> Nov 12, 2007 03:11:37.0150 UTC
RTP: 671123120
871: RTSP/PLAY-Request from CLIENT
881: RTCP-SR/9303 from LENC
NTP: MSW: 3403825898 (0xcae242ea); LSW: 64424509
(0x03d70a3d) ==> Nov 12, 2007 03:11:38.0150 UTC
RTP: 383834926
882: RTCP-SR/3457 to CLIENT
Same as 881
906: RTCP-RR/3457 from CLIENT
919: RTCP-SR/9301 from LENC
NTP: MSW: 3403825899 (0xcae242eb); LSW: 133143986
(0x07ef9db2) ==> Nov 12, 2007 03:11:39.0310 UTC
RTP: 671303570
920: RTCP-SR/9301 to CLIENT
Same as 919
921: RTP/9302 from LENC
Seq: 39932
RTP: 383841717
922: RTP/3456 to CLIENT
Same as 921
923: RTP/9300 from LENC
Seq: 59095
RTP: 671369087
924: RTP/9302 from LENC
Seq: 39933
RTP: 383842741
925: RTSP/PLAY-Response to CLIENT
RTP-Info:
url=rtsp://172.28.15.239/rtpencoder/Blah.sdp/streamid=1;seq=39932;rtptim
e=383841717,
url=rtsp://172.28.15.239/rtpencoder/Blah.sdp/streamid=0;seq=59095;rtptim
e=671239890
926: RTP/3458 to CLIENT
Seq: 59095
RTP: 671369087
927: RTP/3456 to CLIENT
Seq: 39933
RTP: 383842741
How in the world did HUSM come up with "rtptime=671239890"?????
Is there any reference or commonly cited material about how
these values are calculated?
Thanks in advance,
ChrisB
Chris Burns
M: +64 21 391 286
[EMAIL PROTECTED]
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