Re: [MMUSIC] [rtcweb] Translating Plan A into No Plan (Was: No Plan)

Eric Rescorla <ekr@rtfm.com> Mon, 03 June 2013 21:13 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Mon, 3 Jun 2013 14:07:02 -0700
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To: Emil Ivov <emcho@jitsi.org>
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Cc: "Cullen Jennings \(fluffy\)" <fluffy@cisco.com>, MMUSIC IETF WG <mmusic@ietf.org>
Subject: Re: [MMUSIC] [rtcweb] Translating Plan A into No Plan (Was: No Plan)
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On Mon, Jun 3, 2013 at 2:01 PM, Emil Ivov <emcho@jitsi.org> wrote:

> (moving from rtcweb)
>
> Hey Eric,
>
>
> On 03.06.13, 21:33, Eric Rescorla wrote:
>
>>
>> On Mon, Jun 3, 2013 at 10:28 AM, Emil Ivov <emcho@jitsi.org
>> <mailto:emcho@jitsi.org>> wrote:
>> [...]
>>
>>     III. Talking to other WebRTC applications
>>
>>     This is the fun case and the one we should be most concerned with.
>>     Let's imagine that the answerer needs to add a fourth video stream.
>>     To make this work endpoints would need to do the following:
>>
>>     a) with Plan A and draft-roach-rtcweb-glareless-_**_add:
>>
>>         - send application specific signalling to the offerer
>>         - have a new O/A exchange
>>
>>     b) with Plan A:
>>         - have a new O/A exchange
>>         - potentially risk glare with some impact on user experience
>>
>>     c) with No Plan:
>>         ... nothing
>>
>>
>> I'm really not following how this works in "No Plan". Ignoring Plan A
>> and Plan B, can you just
>> walk through a complete example of what happens in your plan? I.e., how
>> does browser
>> B learn learn that Browser A wants to send 3 streams instead of one?
>>
>
> It just gets three streams instead of one. It sees three new SSRCs and it
> generates three new MediaStreams.
>

So, just for clarity: you mean that A advertises one m-lin, B accepts,
and then A sends some arbitrary number of media flows, identified
by SSRC? If so, I've got some questions:

- If B can only display one video stream, how does it say so?
- How does B tell A not to send various streams?
- How does B tell A to send one stream big and another stream small?

-Ekr