Re: [MMUSIC] BUNDLE: no reason por payload type to be unique within bundled m= lines

Christer Holmberg <> Wed, 09 March 2016 11:40 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 4326C12DDC2 for <>; Wed, 9 Mar 2016 03:40:07 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -4.221
X-Spam-Status: No, score=-4.221 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id wybF81IGbTGK for <>; Wed, 9 Mar 2016 03:40:05 -0800 (PST)
Received: from ( []) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 8725812DFA7 for <>; Wed, 9 Mar 2016 03:40:04 -0800 (PST)
X-AuditID: c1b4fb2d-f79836d000006396-b3-56e00b92cad4
Received: from (Unknown_Domain []) by (Symantec Mail Security) with SMTP id C3.04.25494.29B00E65; Wed, 9 Mar 2016 12:40:02 +0100 (CET)
Received: from ([]) by ([]) with mapi id 14.03.0248.002; Wed, 9 Mar 2016 12:40:01 +0100
From: Christer Holmberg <>
To: =?utf-8?B?J0nDsWFraSBCYXogQ2FzdGlsbG8n?= <>
Thread-Topic: [MMUSIC] BUNDLE: no reason por payload type to be unique within bundled m= lines
Date: Wed, 9 Mar 2016 11:40:01 +0000
Message-ID: <>
References: <> <> <> <> <> <> <>
In-Reply-To: <>
Accept-Language: en-US
Content-Language: en-US
x-originating-ip: []
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64
MIME-Version: 1.0
X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmphkeLIzCtJLcpLzFFi42KZGbE9SncS94Mwg+VvxCym77OxmLr8MYsD k8e5hvfsHkuW/GQKYIrisklJzcksSy3St0vgylj9fBpLwT2+itVrmtkbGNfwdTFyckgImEgc 7XzPDGGLSVy4t56ti5GLQ0jgMKPE28YNTBDOYkaJdVMWsHYxcnCwCVhIdP/TBmkQEbCReD5x MSOIzSwQK/G25TFYibBAvMSTk9EQJQkS0179YoOwoyTeXb3HDFLCIqAi8aAxDCTMK+Ar8evU TKi155klvi99ygKS4BQIlFjSMZsVxGYEuu37qTVMEKvEJW49mc8EcbOAxJI956HuF5V4+fgf K4StKHF1+nImkF3MApoS63fpQ7QqSkzpfsgOsVdQ4uTMJywTGMVmIZk6C6FjFpKOWUg6FjCy rGIULU4tLs5NNzLWSy3KTC4uzs/Ty0st2cQIjJuDW37r7mBc/drxEKMAB6MSD29B5P0wIdbE suLK3EOMEhzMSiK8e7gehAnxpiRWVqUW5ccXleakFh9ilOZgURLnZft0OUxIID2xJDU7NbUg tQgmy8TBKdXAmNSrskqX426aj9CG26d0C1VeiF+87KV6QFfN4vK/SWqB61LqQpIOt51c+ycx YgKzOK9wH7vwJgH974fPmb08qj9T+qb+9rsM3k/C6jl//IrtZDbJzlBv4fF6GK//lEGi70vu Nj298ge9lcL/9TgvGNdle3c3mjClqXEyyM/J4b3xd//2v8ZKLMUZiYZazEXFiQBS46DGlwIA AA==
Archived-At: <>
Cc: Magnus Westerlund <>, "" <>
Subject: Re: [MMUSIC] BUNDLE: no reason por payload type to be unique within bundled m= lines
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 09 Mar 2016 11:40:07 -0000


>>    "For sendonly RTP streams, the payload type numbers indicate the value of the payload type field in RTP packets
>>    the offerer is planning to send for that codec."
>> ...followed by:
>>    "However, for sendonly and sendrecv streams, the answer might indicate
>>    different payload type numbers for the same codecs, in which case,
>>    the offerer MUST send with the payload type numbers from the answer."
>> So, for sendonly, the offerer can indicate the values it is "planning" to use, but the answerer will have the final say.
>OK. But what would happen when such a a=sendrecv becomes a=sendonly and later a=recvonly (due "hold" feature for example)? 
>Also note that, depending who sends the re-offer, payload types may have to change within the same RTP "session".

If I could decide, endpoints would always indicate what they want to receive - even if they don't intend to receive anything (in case of inactive or sendonly).

Then, when/if you change the direction, the negotiation is already done, and you can start send/receive based on what you previously negotiated.

But, to answer your question: I don't see what the problem is. If there is an O/A where you will start receiving media, you will simply indicate what PTs you want to receive.



Iñaki Baz Castillo