Re: [MMUSIC] Simulcast draft feedback
"Mo Zanaty (mzanaty)" <mzanaty@cisco.com> Mon, 19 October 2015 22:40 UTC
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From: "Mo Zanaty (mzanaty)" <mzanaty@cisco.com>
To: Byron Campen <docfaraday@gmail.com>
Thread-Topic: [MMUSIC] Simulcast draft feedback
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Date: Mon, 19 Oct 2015 22:40:04 +0000
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Cc: "mmusic@ietf.org" <mmusic@ietf.org>
Subject: Re: [MMUSIC] Simulcast draft feedback
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The convention for existing SDP attributes is to refer to local media formats (PT for RTP media sections). If the answer uses different PTs for the same format, this can lead to complex format matching rules for local vs remote SDP. While I think everyone dislikes this complexity for the limited benefit of supporting asymmetry in PTs, I think simulcast and rid should just stick with the convention. It would be even greater complexity to have an SDP body refer to local PTs in most areas but remote PTs in a few others (rid and simulcast attributes). If we really want to avoid this complexity we need a new attribute like a=symmetric-pt-only independent of simulcast or rid. The complexity is unavoidable without this, because it is a basic thing even in single stream cases which obviously must be supported. There is no way simulcast or rid can avoid this complexity within their own specs. Mo On Oct 19, 2015, at 6:10 PM, Byron Campen <docfaraday@gmail.com> wrote: > On 10/19/15 5:07 PM, Paul Kyzivat wrote: >> On 10/19/15 4:22 PM, Byron Campen wrote: >> >> **** Payload type asymmetry confusion **** >> >> Consider the following simulcast offer/answer exchange, where the >> answerer removes a simulcast version and changes payload types: >> >> offer: >> a=rtpmap:96 VP8/90000 >> a=rtpmap:97 VP8/90000 >> a=rtpmap:98 VP8/90000 >> // a=fmtp that differ for the above three >> a=simulcast: send pt=96;97;98 >> >> answer: >> a=simulcast: recv pt=42;101 > > I don't understand. I think you need to provide more info. Did it change PTs in the m-line of the answer for codec configs the offerer called 96,97,98? Did it add more PTs not mentioned in the offer? It changed the payload types that were present in the offer (same m-section). Best regards, Byron Campen _______________________________________________ mmusic mailing list mmusic@ietf.org https://www.ietf.org/mailman/listinfo/mmusic
- Re: [MMUSIC] Simulcast draft feedback Paul Kyzivat
- [MMUSIC] Simulcast draft feedback Byron Campen
- Re: [MMUSIC] Simulcast draft feedback Byron Campen
- Re: [MMUSIC] Simulcast draft feedback Mo Zanaty (mzanaty)