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RE: Settings retrieval/application API Proposal (formerly: constraint modification API v3)

From: Jim Barnett <Jim.Barnett@genesyslab.com>
Date: Tue, 11 Sep 2012 15:22:37 -0700
Message-ID: <E17CAD772E76C742B645BD4DC602CD8106B5F10E@NAHALD.us.int.genesyslab.com>
To: "Josh Soref" <jsoref@rim.com>, "Media Capture" <public-media-capture@w3.org>
The MinMaxCurrentValue object is interesting.  I suppose that there
could be another one EnumedValCurrentValue for settings that have a
discrete set of legal values.  

- Jim

-----Original Message-----
From: Josh Soref [mailto:jsoref@rim.com] 
Sent: Tuesday, September 11, 2012 5:52 PM
To: Media Capture
Subject: RE: Settings retrieval/application API Proposal (formerly:
constraint modification API v3)

Giridhar wrote:
> Regarding "do whatever the camera manufacturer thinks is appropriate 
> for a function with this name", we do have precedence for providing 
> implementation flexibility in the W3C.

> For instance, the Geolocation API poses no detailed requirements on 
> the underlying platform as to how to interpret the setting

The Geolocation API is generally understood to be a pretty terrible API
in a number of ways. Referencing it isn't a good start to any argument.

Another example of a crappy API is the DeviceOrientation API which was
published by the same WG. It basically has ZERO interop.

> Maybe a more constructive way forward (as opposed to dismissing what 
> I've proposed summarily) would be to at least determine those settings

> that would not derail the standardization effort significantly.

So, "face detection" is an interesting thing. However, while it /may/ be
possible to get interop in the form of "returns a rectangle that may
have a fuzzy face, or an animal, or a statue, or a sculpture, or
something that isn't remotely like a face", I'm not quite sure we're
likely to see better interop than that. And I'm really unsure we'd be
able to get interop on "how much padding will be included in the
detected face boundaries".

An interesting question is can a face region have multiple faces?
Would it be legal to return the entire picture's dimensions (for the
case of a family/team picture, as opposed to an actual badge-photo)?

Calling those QoI distinctions is pretty problematic. If half of the
implementations do it one way, and the other half does it the other way,
you really don't have interop, and Cordova/jQuery and similar groups
will be forced to just write their own shims which do detection they
want manually (and more accurately). By that point, we've just mandated
implementing something that doesn't work (and does add
security/stability risks) and won't be used.

> boolean geotagging;// Default is false; true setting may be ignored if
UA doesn't support.  Note that if UA does not support JPEG then this
feature is disabled.

If the UA supports TIFF instead of JPEG, then I'd expect the tags to be
I'd also expect the tags to just be available from the interface, in
case I'm using PNG and just want to read the tags straight from the
system instead of out of the image.

I'm also pretty sure that the part of speech for your boolean is wrong.
"includeGeotags" or similar is probably better.

There's a similar risk for geotagging. I'd actually prefer that the
geotag be specified as "include a location coord with precision
indicator", this is distinct from features I've seen elsewhere where
such coords are also converted to supposedly human readable strings (but
which may be in all sorts of random languages, with misspellings and
other amusing errors -- this is based on my work @nokia on the n900).

> boolean highDynamicRange;// Default is false; true setting may be 
> ignored if UA doesn't support

Similarly, I'd expect "captureHDR" or "useHDR" or something. 

Personally, on the subject of how things should be shaped, I suspect I'd
rather a single object attribute for a set of related things:

Interface FloatMinMaxCurrentValue {
 float value;
 float min;
 float max;
Interface SharpnessConstraints {
 FloatMinMaxCurrentValue sharpness;

Interface RotationConstraints {
FloatMinMaxCurrentValue rotation;

Interface BrightnessConstraints {
FloatMinMaxCurrentValue brightness;
PictureInfo implements SharpnessConstraints; PictureInfo implements
RotationConstraints; PictureInfo implements BrightnessConstraints;

One advantage of this, is that people are much less likely to misspell
I'm speaking as someone who just spent a week cursing a dozen groups for
not being able to spell words (jQuery: Suppress has two p's, WAI:
labeled does not have doubled L's, qunit: grr, jasmine: grr, ...).

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Received on Tuesday, 11 September 2012 22:22:55 UTC

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