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Re: [Bug 23820] New: Add special values for PropertyValueRange to enable preference specification in optional constraints

From: Martin Thomson <martin.thomson@gmail.com>
Date: Wed, 20 Nov 2013 09:26:57 -0800
Message-ID: <CABkgnnUxZK94sK4017Cy8OiVxm8QKCJFC1nZ-0Up7DcZr-m7Pg@mail.gmail.com>
To: Jan-Ivar Bruaroey <jib@mozilla.com>
Cc: "public-media-capture@w3.org" <public-media-capture@w3.org>
On 20 November 2013 08:17, Jan-Ivar Bruaroey <jib@mozilla.com> wrote:
> Shouldn't we first nail down what min and max mean? e.g.

This I agree with.  But the answer might not be as deterministic as
you might like.

> - Does { mandatory: { width: { min: 1024 } } } conservatively give me
> 1024x768
>   or the highest available because I didn't constrain upward?
>
> - Does { mandatory: { width: { max: 2880 } } } aggressively give me
> 2880x1800
>   or the lowest available because I didn't constrain downward?
>
> - Given choices, what does { mandatory: { width: { min: 1024, max: 2880 } }
> } give me?

The answer to these is universally, "I don't know".  And I think that
I am perfectly comfortable with that.

> I think we need to establish default behavior of the algorithm here (please
> point me to it if this is already done).

I disagree.  Obviously, we would like to have a situation where the
"best" source is selected, but that is a multi-dimensional
optimization problem that the browser is required to manage.  Then
there is user preference thrown in.

When you get down to it, constraints on selection are just additional
input into the selection algorithm that the browser chooses to
implement.

Given that, I think that it would be folly to specify an algorithm to
the extent that different browsers produce identical results for all
variations of constraints and sources.  There's a place for
standardization, but I don't think that this is it.

I don't think that having additional preferences is necessary.  That
is the function that optional constraints fulfill already.  Having
more ways to influence the selection algorithm is only going to make
it harder to build and understand.  I worry that we are already in
that situation; let's not make it worse.

(Actually, I do like the "prefer" suggestion.  But it's duplicative,
so I'd be interested only if you also remove optional constraints at
the same time.  I consider that to be an unlikely outcome at this
stage.)
Received on Wednesday, 20 November 2013 17:27:24 UTC

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