Re: [rtcweb] #21: Section 4.1: max-ssrc

Magnus Westerlund <> Mon, 26 August 2013 06:18 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id BC94511E8160 for <>; Sun, 25 Aug 2013 23:18:59 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -105.397
X-Spam-Status: No, score=-105.397 tagged_above=-999 required=5 tests=[AWL=0.852, BAYES_00=-2.599, HELO_EQ_SE=0.35, RCVD_IN_DNSWL_MED=-4, USER_IN_WHITELIST=-100]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id kcMcl0W-0ml8 for <>; Sun, 25 Aug 2013 23:18:53 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id 0DED211E815E for <>; Sun, 25 Aug 2013 23:18:52 -0700 (PDT)
X-AuditID: c1b4fb25-b7eff8e000000eda-92-521af34b833b
Received: from (Unknown_Domain []) by (Symantec Mail Security) with SMTP id 9B.27.03802.B43FA125; Mon, 26 Aug 2013 08:18:51 +0200 (CEST)
Received: from [] ( by ( with Microsoft SMTP Server id 14.2.328.9; Mon, 26 Aug 2013 08:18:51 +0200
Message-ID: <>
Date: Mon, 26 Aug 2013 08:20:01 +0200
From: Magnus Westerlund <>
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130801 Thunderbird/17.0.8
MIME-Version: 1.0
To: rtcweb issue tracker <>
References: <>
In-Reply-To: <>
X-Enigmail-Version: 1.5.2
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8bit
X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrMLMWRmVeSWpSXmKPExsUyM+Jvja73Z6kgg0+vVCz2L7nMbDG/q5XV Yu2/dnaL+zvLHVg8HvecYfNYsuQnk8eXy5/ZPH7u2cwawBLFZZOSmpNZllqkb5fAlXHy9Cb2 gs0CFf9W9LA1MC7h7WLk5JAQMJFomLqPBcIWk7hwbz1bFyMXh5DAYUaJA49/sEM4yxglHv2d ztTFyMHBK6Ap0bu/GKSBRUBVonftW0YQm03AQuLmj0Y2EFtUIFiifftXMJtXQFDi5MwnYAtE BKwkrlyeCBZnFkiS2L7oNBOILSxgIHHp+EkwW0jATaLjZT9YDaeAu8TmGzsYIY6TlNi26Bg7 RK+mROv231C2vETz1tnMEL3aEg1NHawTGIVmIVk9C0nLLCQtCxiZVzGy5yZm5qSXG21iBAb0 wS2/VXcw3jkncohRmoNFSZx3s96ZQCGB9MSS1OzU1ILUovii0pzU4kOMTBycUg2Miw28F9e0 RqxxPcv15JiW3V++4z2NjN8TGXmnPfgp2xFqecXLfQ0z78kNBwzfcwqbtPPV1ZzLmpPKapJQ 43FDcJaa7O1ZJo8qYk4qf7zUz5jJZ3jtXM+EiHMzpjYd2yljt7lh5nF32TzTg37X7i6dnfHJ y2Zec61W+qSAZ6en8X2U3hK07YueEktxRqKhFnNRcSIAZ04sLTYCAAA=
Subject: Re: [rtcweb] #21: Section 4.1: max-ssrc
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 26 Aug 2013 06:18:59 -0000

On 2013-08-26 00:20, rtcweb issue tracker wrote:
> #21: Section 4.1: max-ssrc
>  (tbd: is draft-westerlund-mmusic-max-ssrc-01 needed?)
>  [BA] I am not a fan of max-ssrc.  Within layered coding it is possible to
>  send multiple layers either with the same SSRC or with different SSRCs.
>  In such a case the maximum number of layers that can be sent or received,
>  and the number of maximum number of SRCNAMEs, is more relevant that the
>  maximum number of SSRCs.  Therefore I would prefer not to see max-ssrc
>  used in WebRTC (or anything else, for that matter).

I find this comment intriguing and I think important to understand for
the usage of SVC in context of a single RTP session. So you are saying
that you intended to use multi-stream transmission of SVC within a
single RTP session. Could you please expand on the motivation for this
as it will be a requirement effecting signalling requirements. I would
note that SVC MST media streams with multiple media sources in a single
RTP stream may have issues being correctly associated.

Regarding Max-SSRC signalling:
Okay, let me reformulate this question from SSRCs to media decoders.
This as the max-ssrc is designed to be able to express limitations on
number of simultaneous decoders for different codecs a receiver can
handle through the usage of the SSRC and PT combination. Other designs
for this type of signaling is possible.

Are there interest in the WG to be able to indicate the limitations of a
receiver in how many simultaneous media streams a receiver can decode
and thus makes sense to transmit to it?


Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVM
Ericsson AB                | Phone  +46 10 7148287
Färögatan 6                | Mobile +46 73 0949079
SE-164 80 Stockholm, Sweden| mailto: