W3C home > Mailing lists > Public > public-media-capture@w3.org > December 2012

Re: Proposal for device "enumeration"

From: Martin Thomson <martin.thomson@gmail.com>
Date: Fri, 7 Dec 2012 09:42:15 -0800
Message-ID: <CABkgnnUpP4Y5uTSVmq3WxieWTum+0iALb=ZrURg1jjA4BAg3vQ@mail.gmail.com>
To: Adam Bergkvist <adam.bergkvist@ericsson.com>
Cc: "public-media-capture@w3.org" <public-media-capture@w3.org>
On 6 December 2012 21:51, Adam Bergkvist <adam.bergkvist@ericsson.com> wrote:
> Is the gain of enumerating the deviceIds that high that it's worth the
> finger printing surface?

The fingerprinting surface provided by this is exactly equivalent to
getNumDevices() as Travis proposed.  The advantages are that you can
build an application that has consistent behaviour over time.

> Couldn't you solve the use case of requesting a specific specific camera
> (you have used before and know works) by only exposing the deviceId on that
> source and having a constraint to request that particular device again with
> getUserMedia()?

That is the alternative, if you consider the idea that this amount of
increase in fingerprinting is unacceptable.  The only two options with
smaller fingerprinting area than this are:
 a) don't provide a way to discover if the user has devices of a given type
 b) provide a way to detect that devices of a given type exist, but not how many
Then we have:
 c) this proposal - let the application discover how many devices
exist for a given type
And if we consider fingerprinting to be a lost cause:
 d) let the application know about devices to some degree (facing, max
 e) let the application know everything

I don't believe that option (a) is tolerable for all the
aforementioned reasons.  (b) would enable re-acquisition of devices,
which I think I would be OK with*.  (e) is such a radical departure
from contemporary practice that I don't believe them to be even worth
considering.  (d) might actually be useful...

The thing that bothers me most about just knowing about the existence
of cameras (even with case (c)) is the first generation iPhone and
devices of its ilk.  These have one camera that faces away from the
user.  This camera is useless for communications applications.
Getting an indication that a camera exists is therefore insufficient
for those applications to know whether to offer video chat.  This is
where (d) starts to be tempting.  But I'm not there yet.
Received on Friday, 7 December 2012 17:42:44 UTC

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