[AVT] Computing audio/video skew using RTP/RTCP timestamp
"Amit Danziger" <amitdanz@hotmail.com> Wed, 04 June 2003 18:48 UTC
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From: Amit Danziger <amitdanz@hotmail.com>
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Subject: [AVT] Computing audio/video skew using RTP/RTCP timestamp
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Hi, I'm trying to figure out how to compute RTP audio/video streams skew at the receiver side. Here's what I know: Audio clock - Ca (8000Hz) Video clock - Cv (90000Hz) RTCP SR info: Audio NTP timestamp - Na, Video NTP timestamp - Nv Audio RTP timestamp - Ra, Video RTP timestamp - Rv If I understand correctly I should calculate delta between streams (audio - video)as: D = (Ra / Ca - Rv / Cv) - (Na - Nv) Now, in order to compute the skew between two received RTP packets (assuming they were received simultaneously): Audio timestamp - Ta, Video timestamp - Tv Skew = (Ta / Ca - Tv / Cv) + D I'm not sure why, BUT somewhere along the way I'm mistaken. The numbers just don't make sense. I'd be glad to hear any ideas. Thanks, Ami Tdanz _________________________________________________________________ MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. http://join.msn.com/?page=features/virus _______________________________________________ Audio/Video Transport Working Group avt@ietf.org https://www1.ietf.org/mailman/listinfo/avt
- [AVT] Computing audio/video skew using RTP/RTCP t… Amit Danziger