Re: [MMUSIC] Simulcast: Short timelines, draft impending

Suhas Nandakumar <suhasietf@gmail.com> Fri, 02 October 2015 22:48 UTC

Return-Path: <suhasietf@gmail.com>
X-Original-To: mmusic@ietfa.amsl.com
Delivered-To: mmusic@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 999561B31DA for <mmusic@ietfa.amsl.com>; Fri, 2 Oct 2015 15:48:10 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.999
X-Spam-Level:
X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, SPF_PASS=-0.001] autolearn=ham
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id e1o3FtiKssik for <mmusic@ietfa.amsl.com>; Fri, 2 Oct 2015 15:48:08 -0700 (PDT)
Received: from mail-vk0-x241.google.com (mail-vk0-x241.google.com [IPv6:2607:f8b0:400c:c05::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 08D6D1B31D7 for <mmusic@ietf.org>; Fri, 2 Oct 2015 15:48:08 -0700 (PDT)
Received: by vkgd64 with SMTP id d64so5610386vkg.0 for <mmusic@ietf.org>; Fri, 02 Oct 2015 15:48:07 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=Wjp3gt/t4Q2ktafx/aaDmW11u90I84Y+99IbIdzll3c=; b=WkFSDLxFK078ZhALJysMBE94bxhJNQBSl1o76UyLLlyIjrmO0ZV0AHuaWmjhngUnBf T+WZM8qO7yoZfRGXuZA5kF2XmJwVxVJMOmxr+9AuCydFdG9x0pNe6esNnpWOV7+fQjDX fa5zK2MilDWCVvtZzRNEvuzDksWfC1JVFQrEXJG4cfY4HMsaQOEUi2vwGrsM3tRkG9bO DVwqFQqxw2X2oFFBBUNa0pVO3WKUJl9KsYnCjtcXGDLH882mam7pUDydBJdUl/QC4lR4 a3Q/PHMyjfzYHnJkh8DJwBVLZ3v4CMLeEO2RbM3J9+zh4RMYO0vFBesRucRKX7MuE9uh sXmA==
MIME-Version: 1.0
X-Received: by 10.31.52.214 with SMTP id b205mr12073551vka.122.1443826086968; Fri, 02 Oct 2015 15:48:06 -0700 (PDT)
Received: by 10.31.172.151 with HTTP; Fri, 2 Oct 2015 15:48:06 -0700 (PDT)
In-Reply-To: <5604B29B.9070005@nostrum.com>
References: <5604B29B.9070005@nostrum.com>
Date: Fri, 2 Oct 2015 15:48:06 -0700
Message-ID: <CAMRcRGQngExyrL0doFidea19D8QAvCAgwjoaS=DO+upNGXxL0w@mail.gmail.com>
From: Suhas Nandakumar <suhasietf@gmail.com>
To: Adam Roach <adam@nostrum.com>
Content-Type: multipart/alternative; boundary=001a1143f932080578052126f51a
Archived-At: <http://mailarchive.ietf.org/arch/msg/mmusic/UErKhAyu52hX1zPYkX1sV1hY0xo>
Cc: "mmusic@ietf.org" <mmusic@ietf.org>
Subject: Re: [MMUSIC] Simulcast: Short timelines, draft impending
X-BeenThere: mmusic@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <mmusic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mmusic>, <mailto:mmusic-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/mmusic/>
List-Post: <mailto:mmusic@ietf.org>
List-Help: <mailto:mmusic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mmusic>, <mailto:mmusic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 02 Oct 2015 22:48:10 -0000

Hello All

   As indicated by Adam in his email , we have submitted the draft defining
"RID".

   The draft can be found here:
https://datatracker.ietf.org/doc/draft-pthatcher-mmusic-rid/?include_text=1

   Please provide your feedback on the same.

Thanks
Suhas

On Thu, Sep 24, 2015 at 7:34 PM, Adam Roach <adam@nostrum.com> wrote:

> At the W3C WebRTC interim meeting a couple of weeks ago, one of the issues
> that the group was not able to resolve was how to enable the use of
> simulcast for WebRTC browser implementations. A key point of contention was
> the use of unique payload types for each simulcast encoding in the current
> MMUSIC document (draft-ietf-mmusic-sdp-simulcast-01). Combined with the
> other features planned for WebRTC, there is concern that such an approach
> may lead to PT exhaustion within a session under certain reasonably
> expected circumstances.
>
>
> As important context: the WebRTC 1.0 specification is rapidly approaching
> finalization, and the working group hopes to leave the TPAC meeting at the
> end of October with all of the loose ends tied up. Simulcast is one of the
> more important and one of the most loose ends in the specification at the
> moment. As a result, we sincerely hope that we can come to consensus on a
> viable approach in MMUSIC over the next few weeks. To be explicit: the TPAC
> meeting is the week before the Yokohama IETF meeting, so we cannot afford
> to wait for the ordinary meeting-driven work schedule to push simulcast
> along. We hope to foster a useful and productive conversation on the
> mailing list well ahead of IETF 94.
>
>
> While there were some “hallway discussions” in Prague to discuss potential
> approaches that would address these concerns, none of these have yet been
> documented and shared with the mailing list.
>
>
> After significant conversations both at and after the interim WebRTC
> meeting, and considering information about the type of solutions that
> interested parties are likely to find acceptable, a number of the WebRTC
> participants have come up with a tentative proposal that we believe is
> likely to be simple, flexible, and satisfactory to everyone involved. At a
> high level:
>
>
>  *
>
>    The current behavior described in the MMUSIC simulcast draft remains
>    valid.
>
>  *
>
>    Additionally, we define a new attribute type (provisionally called
>    “RID”, for “RTP Stream ID”) that can be used to define additional
>    codec-independent constraints on PTs (e.g., max-fps, max-bps,
>    max-width, max-height).
>
>  *
>
>    RIDs can be defined to be unidirectional, so as to allow
>    implementations to signal the ability to send a different number of
>    encodings than they can receive.
>
>  *
>
>    The values for each constraint can be specified to be different in
>    each direction.
>
>  *
>
>    When used, the RID value is encoded as part of the RTP packet, in an
>    extension header.
>
>  *
>
>    The values (that is, identifiers) used for RID are proposed by the
>    offerer in a session, and are symmetric. The RID values in an answer
>    must be a subset of those present in the offer.
>
>  *
>
>    The parameters associated with a RID can be made more restrictive
>    (i.e., resolution decreased, bandwidth decreased), but not less
>    restrictive, in an answer.
>
>  *
>
>    For those sessions that use RIDs, the “a=simulcast” parameter is
>    enhanced to be able to carry RIDs instead of PTs.
>
>
> We hope to have an internet-draft that describes this approach in more
> detail by the end of next week.
>
> /a
>
> _______________________________________________
> mmusic mailing list
> mmusic@ietf.org
> https://www.ietf.org/mailman/listinfo/mmusic
>