Re: About the Mandatory constraints

On 2/5/14 1:34 PM, Stefan Håkansson LK wrote:
> There has been some discussion about mandatory constraints again lately
> in the context of constraints for the MediaStream Recorder.
>
> I think the use of constraints for the Recorder is something we have not
> really discussed yet, but I think (though I may be wrong) some mails
> tended to question the need for mandatory constraints also for gUM.

You are not wrong:

On 2/5/14 1:17 PM, Robert O'Callahan wrote:
> On Thu, Feb 6, 2014 at 6:29 AM, Cullen Jennings <fluffy@iii.ca 
> <mailto:fluffy@iii.ca>> wrote:
>
>     Is this a proposal for GUM for Recording or both?
>
>
> Both. Paragraphs 1-4 apply to both.

Paragraphs 3 and 4 being:
>>> 3) Eliminate getConstraints(). The application can determine which 
>>> constraints were satisfied by inspecting object state using #2.
>>> 4) Eliminate mandatory constraints for the same reason.


On 2/5/14 1:34 PM, Stefan Håkansson LK wrote:
> Just to be clear: I think we have debated the mandatory constraints for
> gUM several times, and we always come back to the same conclusion:
> people want them. One use is when the app developer wants to avoid
> disturbing the user, or even indicate e.g. that video communication is
> possible, if the equipment does not fulfill the requirements the app
> developer has.
>
> Some people think it would be more natural to just get access to the
> camera (and in the process launch a prompt), then check what it can
> fulfill the needs, and if not tell the user that "sorry, your camera is
> not good enough". But those developers can skip using mandatory constraints.

Well described. Thank you for succinctly nailing the lone benefit of 
mandatory constraints: to avoid a permission prompt in a failure case.

BTW, gUM has a permission prompt, MediaRecorder does not.

> Let's not debate if we need mandatory constraints or not for gUM again.
> I think it would be much more fruitful if we could have the details in
> Constrainable reviewed for use with gUM and MediaStreamTracks. I would
> be really happy we could nail a design that fulfills the needs we have
> there.

I think we would be done discussing constraints if not for people trying 
to elevate Constrainable to a general interface and foisting it on other 
APIs. That's a higher bar that opens the door for further scrutiny.

I would be happy to scrutinize other uses of the interface if there were 
any.

Since there aren't, are we not supposed to talk about that the elephant 
being sold has five legs, or that how it got five legs was controversial?

.: Jan-Ivar :.