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Re: [rtcweb] Proposal for dealing with CNAMEs and MSIDs for synchronization

Jim Barnett <Jim.Barnett@genesyslab.com> Thu, 07 February 2013 19:27 UTC

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From: Jim Barnett <Jim.Barnett@genesyslab.com>
To: Eric Rescorla <ekr@rtfm.com>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Thread-Topic: [rtcweb] Proposal for dealing with CNAMEs and MSIDs for synchronization
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Date: Thu, 07 Feb 2013 19:27:03 +0000
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Subject: Re: [rtcweb] Proposal for dealing with CNAMEs and MSIDs for synchronization
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On point 2,  do you mean "same MediaStream"?


-          Jim

From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On Behalf Of Eric Rescorla
Sent: Thursday, February 07, 2013 2:22 PM
To: rtcweb@ietf.org
Subject: [rtcweb] Proposal for dealing with CNAMEs and MSIDs for synchronization

Here's what I was trying to say at the microphone.

1. When two MSTracks are in the same MediaStream on the sending side:
 They must generate the same MSID in SDP and the same CNAME in RTP.

2. One the receiving side, any two tracks with the same MSID will appear in
the same MediaStreamTrack.

3. On the receiving side, any two RTP streams with the same CNAME will
be synchronized.

4. There are two ways for MSID and CNAME to be inconsistent.
- If MSID indicates synchronization but different CNAMEs are provided,
  synchronization is not attempted.
- If MSID indicates no synchronization but the same CNAME is used,
  then the tracks shall be synchronized, even though they appear in
  different MediaStreams.

-Ekr

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