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

Re: Implementation suggestions

From: Stefan Hakansson LK <stefan.lk.hakansson@ericsson.com>
Date: Wed, 6 Jun 2012 08:45:38 +0200
Message-ID: <4FCEFC92.6040400@ericsson.com>
To: public-media-capture@w3.org
On 06/06/2012 06:36 AM, Anant Narayanan wrote:
> Hi Group,
> I have added a new non-normative section titled "Implementation
> Suggestions". The first two pieces of content that the section includes
> are two issued that we brought up at the last telco. I hope we will add
> more content such as UI guidelines for browsers, and expected usage
> patterns for getUserMedia in the future.
> - Resource reservation: how devices are generally expected to be
> reserved, and recommending that the user be allowed to terminate running
> sessions in favor of providing a stream to the current page.
> - Multiple streams: Suggesting that multiple calls to getUserMedia from
> the same page be allowed and handled in a sane manner in order to allow
> the page to get independent video or audio streams.
> Please review the latest draft at
> http://dev.w3.org/2011/webrtc/editor/getusermedia.html (section 3.5) and
> send your feedback to the list!

I think this looks generally good. I have a couple of questions and 

Resource reservation:

* It is said that resources that are allocated already as a result of 
earlier calls to getUserMedia should be presented as busy (with the 
option to terminate that stream and allow use for the current 
getUserMedia instead. My question: what about resources that are taken 
by other native apps than the browser? Could this be detected, and could 
any understandable info be presented to the user?

* On the same theme: it is said that if the user selects to allocate a 
resource that is already taken by an earlier call to getUserMedia, the 
existing LocalMediaStream should be stopped. However, perhaps the 
conflict is only for one of several tracks in the existing 
LocalMediaStream. An alternative approach could be that only the 
relevant tracks of the existing LocalMediaStream are ended (and the 
stream ended only if all tracks are "taken").

* It is said that "the user be allowed to select any available hardware 
as a source"; should it not be gated by available HW that fulfills 
mandatory constraints?

* About using files: I guess we need to spec how the browser should find 
such files. I mean, the browser can't scan the entire computer for files 
of certain types every time getUserMedia is called, rigth?

Handling multiple devices

* Should there a way for the application to indicate that it wants only 
one audio and one video track when calling getUserMedia? If this was 
possible, the browser could then make the selections "exclusive-or" when 
set, "and" when not set.

> Regards,
> -Anant
Received on Wednesday, 6 June 2012 06:46:08 UTC

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