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Re: [rtcweb] SDP and ssrc-group,

"Makaraju, Maridi Raju (Raju)" <Raju.Makaraju@alcatel-lucent.com> Wed, 22 October 2014 22:05 UTC

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From: "Makaraju, Maridi Raju (Raju)" <Raju.Makaraju@alcatel-lucent.com>
To: Bernard Aboba <bernard.aboba@gmail.com>
Thread-Topic: [rtcweb] SDP and ssrc-group,
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Subject: Re: [rtcweb] SDP and ssrc-group,
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RFC 5576 makes it clear that partial rejection is not supported.
<Raju>
True, http://tools.ietf.org/html/rfc5576#section-8 did say that. Thanks for pointing it out.
Section 9 says the following; which still say there may be a need for explicit source descriptions are needed. The receiver does not understand this RFC 5576 so it would ignore unknown a=ssrc-group or rtx/apx payload. Then how does it know which ssrc (it does understand a=ssrc lines) is original?
9<http://tools.ietf.org/html/rfc5576#section-9>.  Backward Compatibility
   According to the definition of SDP, interpreters of SDP session
   descriptions ignore unknown attributes.  Thus, endpoints MUST be
   prepared that recipients of their RTP media session may not
   understand their explicit source descriptions, unless some external
   mechanism indicates that they were understood.  In some cases (such
   as RTP Retransmission [RFC4588<http://tools.ietf.org/html/rfc4588>]), this may constrain some choices
   about the bitstreams that are transmitted.

</Raju>

BR
Raju

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