Re: [MMUSIC] [rtcweb] Quick comments on draft-roach-rtcweb-glareless-add-00

[Bernard Aboba <[e-mail]>]

> On 5/10/13 2:37 AM, Stefan Håkansson LK wrote:
>> 
>> 
>> Just as an example, think about a conference scenario with a centralized
>> node. Now, one of the participants wants to mute her/his audio, and as a
>> result the audio m-line would go from sendrecv to recvonly. At roughly
>> the same time the server wants to disable the high res video and enable
>> the low res video (because this user will be moved, based e.g. on the
>> recent audio activity, from being displayed in the main video window to
>> be in a thumbnail on the screen of the other participants in the
>> conference), so it wants to manipulate the direction attribute of other
>> m-lines.
>> 
>> So there would be two offers sent at roughly the same time, which means
>> we would have glare.

There are implementations where no signalling is required for the mixer to go from high res to lower res. For example, if the receiver declares what it can receive and the mixer selects the simulcast stream for that receiver based on capabilities and conditions, with the stream properties declared in band.