W3C home > Mailing lists > Public > public-media-capture@w3.org > May 2015

Re: Filtering of enumerateDevices() results

From: Joe Berkovitz <joe@noteflight.com>
Date: Wed, 20 May 2015 09:00:33 -0700
Message-ID: <CA+ojG-Z49t2FhOwwG_j-2sM+4onGXCByToDVQNpKVFDX0a9GFQ@mail.gmail.com>
To: Harald Alvestrand <harald@alvestrand.no>
Cc: public-media-capture@w3.org, Stefan HÃ¥kansson <stefan.lk.hakansson@ericsson.com>, Audio Working Group <public-audio@w3.org>
> > 1. For audio devices, channel count and a binaural (essentially,
> > speaker-vs-headphone) flag are important attributes.
> Query - are these distinct attributes or points on the same continuum?
> ie will a monaural device always have channel count 1? Or is the
> "binaural" flag specifically for the headphone case, with "each ear of
> the listener hears one and only one channel"?

These are distinct attributes.  "Binaural" means the device delivers a
signal to each ear of the listener separately, as in headphones.

Although it seems this might be restricted to the 2-channel case, perhaps
it's better not to legislate that. The species might evolve :-)

> 2. How would the WG feel about including more "filtered" information in
> > the MediaDeviceInfos returned by enumerateDevices(), other than the
> > device label -- information that the application can use to restrict or
> > augment the list of devices displayed to a user (since constraints are
> > not accepted by enumerateDevices())? Ideally channel count, binaural,
> > sample rate and other attributes such as width and height could be
> > exposed here.
> Query - do you think of these things as singular attributes or as a
> range of possible values? IE some devices are capable of being
> configured into multiple sample rates - what info would you want?

Hmmm, I hadn't considered. If the information is returned in each
MediaDeviceInfo object then perhaps a range would be necessary. In which
case the approach of submitting constraints to enumerateDevices() (to be
ignored if filtering is in effect) might be superior.

> Also - what do you think of when you say "width" and "height" here? Are
> you thinking of video sources, or is there something new here?

I was thinking of video sources.

> If we don't care about fingerprinting, exposing the result of calling
> getCapabilities() on a device might be OK. Or not....

I think that may not  work for this purpose because one would have to call
getUserMedia() for every device in the enumerated list... with lots of
permission grant interactions with the user.

.            .       .    .  . ...Joe
Received on Wednesday, 20 May 2015 16:01:02 UTC

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