Re: [rtcweb] m=section recycling and a=mid

Christer Holmberg <christer.holmberg@ericsson.com> Thu, 19 September 2013 16:36 UTC

From: Christer Holmberg <christer.holmberg@ericsson.com>
To: Suhas Nandakumar <suhasietf@gmail.com>, "rtcweb@ietf.org" <rtcweb@ietf.org>
Thread-Topic: [rtcweb] m=section recycling and a=mid
Thread-Index: AQHOtI5OlzgN5l68MU+Yf86f9mtTsJnNP/0ZgAADHRE=
Date: Thu, 19 Sep 2013 16:35:51 +0000
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Subject: Re: [rtcweb] m=section recycling and a=mid
Precedence: list

Hi,



Below is some suggested BUNDLE text:



6.4.5.  Moving A Media Description Out Of A BUNDLE Group

   When an Offerer generates an Offer, in which an "m=" line is moved
   out of a BUNDLE group, the Offerer MUST assign a unique address to
   the moved "m=" line.  In addition, the Offerer MUST NOT anymore
   include a mid value, representing the "m=" line, in the SDP
   group:BUNDLE attribute mid list associated with the BUNDLE group.

   Section 11.4 shows an example of an Offer used to move an "m=" line
   out of a BUNDLE group.



Regards,



Christer



________________________________
From: rtcweb-bounces@ietf.org [rtcweb-bounces@ietf.org] on behalf of Christer Holmberg [christer.holmberg@ericsson.com]
Sent: Thursday, 19 September 2013 7:24 PM
To: Suhas Nandakumar; rtcweb@ietf.org
Subject: Re: [rtcweb] m=section recycling and a=mid


Hi Suhas,



The mid attribute itself does not add an m- line to a BUNDLE group. The attribute value also needs to be listed in the group:BUNDLE attribute mid list.



So, if you want to re-use an m- line and mid attribute, but you don't want the m- line to be in the BUNDLE group, simply remove the mid from the mid list.



Regards,



Christer



________________________________
From: rtcweb-bounces@ietf.org [rtcweb-bounces@ietf.org] on behalf of Suhas Nandakumar [suhasietf@gmail.com]
Sent: Wednesday, 18 September 2013 7:44 PM
To: rtcweb@ietf.org
Subject: [rtcweb] m=section recycling and a=mid

After thinking about it a bit, I think there are some side effects associated with changing/not changing mid attribute of a re-cycled m= section and it being part of a BUNDLE group or not..

example

say , we have these video m=section part of BUNDLE group as below
a=group:BUNDLE 1, 2

m=video .....
a=mid:1
a=inactive

m=video .....
a=mid:2
a=sendrecv

Now If JS user adds a new video track and he wants it to be out of BUNDLE. If we recycle first video m=section and dont change mid attribute,  we end up BUNDLing even if the user dint want to

On the other hand, if we allowed mid value to be changed, we might end up UNBundling a video stream , when the user did want to BUNDLE them

So allowing a mid value to be changed or not should be tied to what the JS API is asking on behalf of the user


Any thoughts ?

Cheers
Suhas

[rtcweb] m=section recycling and a=mid Suhas Nandakumar
Re: [rtcweb] m=section recycling and a=mid Christer Holmberg
Re: [rtcweb] m=section recycling and a=mid Christer Holmberg
Re: [rtcweb] m=section recycling and a=mid Suhas Nandakumar
Re: [rtcweb] m=section recycling and a=mid Christer Holmberg
Re: [rtcweb] m=section recycling and a=mid Harald Alvestrand
Re: [rtcweb] m=section recycling and a=mid Suhas Nandakumar
Re: [rtcweb] m=section recycling and a=mid Christer Holmberg