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Re: Simulcast V1

From: Peter Thatcher <pthatcher@google.com>
Date: Thu, 20 Aug 2015 09:46:49 -0700
Message-ID: <CAJrXDUEPcMpN=F-N-aP1hUUf+oppApCaxpfs-e2bdKFLOV3vVA@mail.gmail.com>
To: Adam Roach <adam@nostrum.com>
Cc: Byron Campen <docfaraday@gmail.com>, Harald Alvestrand <harald@alvestrand.no>, "public-webrtc@w3.org" <public-webrtc@w3.org>, Bernard Aboba <Bernard.Aboba@microsoft.com>
On Thu, Aug 20, 2015 at 7:50 AM, Adam Roach <adam@nostrum.com> wrote:

> On 8/20/15 09:02, docfaraday@gmail.com wrote:
> [I]t now sounds like we have disagreements on how simulcast should be
> signaled in SDP.
> Let's be clear here.
> The way things are encoded and go on the wire is in the purview of the
> IETF, not the W3C. The format of SDP is in the purview of the IETF, not the
> W3C.
> MMUSIC has a charter item and an adopted draft that details how simulcast
> works.

​But that draft has a long way to go before being finished, so it's
probably not good to rely on it yet.  Right now, at best, we can say "it
will be possible to represent simulcast in SDP someday, in some way".​

> *It is not in charter for any W3C working group or community group to
> define a competing specification for how simulcast works.* If we're doing
> simulcast, the SDP and media will track whatever MMUSIC defines.

​Which means that all the API surface you need is already there.  Pass down
the right SDP from JS, and you're done.  Just like codec selection,
bandwidth caps, resolutions, and just about everything else.​  We don't
need to add anything in the W3C.

> Anyone who cares about how this is signaled in JSEP or how it is encoded
> in RTP and RTCP needs to have a conversation, in MMUSIC, about the contents
> of the existing adopted simulcast working group draft.
> What *this* working group can consider is what the JavaScript API looks
> like for controlling the IETF-defined simulcast mechanisms, and that's the
> conversation I was trying to have.

> /a
Received on Thursday, 20 August 2015 16:47:57 UTC

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