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RE: Should we enable pre-view images for gUM?

From: Mathieu Hofman <Mathieu.Hofman@citrix.com>
Date: Thu, 28 Jan 2016 19:17:37 +0000
To: Iñaki Baz Castillo <ibc@aliax.net>, Martin Thomson <martin.thomson@gmail.com>, Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
CC: Harald Alvestrand <harald@alvestrand.no>, "public-media-capture@w3.org" <public-media-capture@w3.org>
Message-ID: <3CD080DCDA030D47B8ED720F6B99FC810D66F509@SJCPEX01CL02.citrite.net>
> 2016-01-28 5:06 GMT+01:00 Martin Thomson <martin.thomson@gmail.com>:
> > On 28 January 2016 at 09:23, Iñaki Baz Castillo <ibc@aliax.net> wrote:
> >> My opinion is that if such a feature is *already* feasible within
> >> each web application then it is not needed as a browser built-in feature.
> >
> > But it isn't feasible.  Unless you are making some presumptions about
> > the access control that don't hold in the general case.
> > 
> > I haven't done this, and it's not likely that I'll get to it in the
> > short term, but I believe that this feature can be accomplished almost
> > trivially with a little SVG programming.  An SVG should be able to
> > show video, or audio level meters.  And I think that I can address all
> > of Harald's concerns with some other small tweaks.
> >
> > Maybe I need to do some work and come back with a demonstration.
> -----Original Message-----
> From: Stefan Håkansson LK [mailto:stefan.lk.hakansson@ericsson.com]
> Sent: Wednesday, January 27, 2016 22:23
> That would be interesting to see!
> But, my main concern is that it not clear what issue(s) it would solve.
> For example, the filer of Issue 304 [1] indicated that this kind of pre-view
> would not address the core of that issue.

The issue as reported is that the spec allows User Agents to prompt for permissions when a new device is selected, even if the app already had access to another device of the same class.
This is mostly a concern when the enumerateDevices() API is used to provide a device selection feature built-in the app.
I originally created the issue on Mozilla's bugbase to change the permission behavior (which is within spec) and more closely resemble Chrome's behavior (which is mostly within spec). Mozilla however doesn't want to change its behavior, so what’s allowed by the spec cannot be restricted, and issue [1] cannot be fixed as filed.

Now this doesn't mean the use case the issue is referencing cannot be worked on. As an application implementor, I believe Martin's proposal might help supporting better in-app device selection UIs.
I do have concerns with the proposal, that I detailed in a previous message, but a proof-of-concept might go a long way alleviating those.

> [1] https://github.com/w3c/mediacapture-main/issues/304

> -----Original Message-----
> From: Iñaki Baz Castillo [mailto:ibc@aliax.net]
> Sent: Thursday, January 28, 2016 3:04
> So, this feature is about displaying a video preview(s) within the
> getUserMedia permission prompt? Not sure what that tries to solve, but I
> agree with Harald:
> - No web developer will like how it looks.
> - I would feel terrified if a website captures and displays my webcam even
> before I grant it.

No, this proposal is about providing in-app previews for all devices, webcam and microphones, before the app makes a getUserMedia call.
The idea is that developers would be able to show the preview embedded in their application's UI, so they might prefer it to a browser controlled UI (which is allowed by the current spec, but within the realm of browsers to implement)

The perception by the user that the application seem to have access to the devices without any permission grant is also one of my concern. However, this is only a perception problem as the application wouldn't be able to extract any information from the preview.

Received on Thursday, 28 January 2016 19:18:04 UTC

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