Re: [rtcweb] Mute implementations (Re: More Comments ondraft-ietf-rtcweb-use-cases-and-requirements-07)

Harald,
  Your description below makes me nervous:  with getUserMedia, the user
grants permission to _specific_ media streams (for example audio, or
front camera, but not rear).  If the system wants " to change the source
of a video stream after its creation", shouldn't it be required to ask
permission again?  In this case,  common sense says that it's not
necessary, but that's because we're not changing to an arbitrary
alternative the source (e.g., suddenly switching on the rear camera) but
rather substituting some sort of 'null' or 'dummy' source.  Can we think
of a different way to phrase it?

- Jim

-----Original Message-----
From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On Behalf
Of Harald Alvestrand
Sent: Saturday, June 16, 2012 3:56 PM
To: rtcweb@ietf.org
Subject: Re: [rtcweb] Mute implementations (Re: More Comments
ondraft-ietf-rtcweb-use-cases-and-requirements-07)

On 06/15/2012 11:18 PM, Randell Jesup wrote:
> On 6/15/2012 4:49 PM, Martin Thomson wrote:
>> On 15 June 2012 13:42, Randell Jesup<randell-ietf@jesup.org>  wrote:
>>> I would also suggest that for video-mute that instead of stopping 
>>> video or sending black, the application should send a "mute image".
>>
>> The question I have is whether there is: a) a fixed image/video that 
>> is serialized to RTP b) video "comfort noise", or c) local mute 
>> image/video playback.  If it can't be c, then you might need to 
>> explain yourself.
>
> Either we build it into the system (which I dislike - SetMuteImage() 
> or whathaveyou, though we could), or we put it in the application 
> domain and suggest or assist implementation.
>
> The simple way to handle Mute is to revector the input to a "mute" or 
> "hold" source, and they may not be the same (hold would have "Please 
> Hold" and music, perhaps; mute would have silence and "Muted" or a 
> camera with a circle/slash, etc).  You can also signal that out of 
> band to let the other end take smart action (remove muted video image,

> display "muted" next to a name, etc).  This can be done via 
> DataChannels, for example.  You may then reinvite for Hold to make it 
> one-way, but that's mostly optional.
The resulting requirements seem to me to be:

1) To be able to use a still image as source for a video stream
2) To be able to change the source of a video stream after its creation

Both are requirements on the GetUserMedia API. Can we link these to a
specific use case, or do we need to modify the use case document so that
the requirements are clear?

              Harald

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