W3C home > Mailing lists > Public > public-device-apis@w3.org > December 2009

RE: First stab at the Capture API (aka Camera API)

From: Nick Lothian <nlothian@educationau.edu.au>
Date: Tue, 8 Dec 2009 08:59:16 +1030
CC: public-device-apis <public-device-apis@w3.org>
Message-ID: <C61BBB9C527C5A49A8C9069ABC4B005F15C8267A90@eduau-mail.eduau.local>
> >
> > An ability to set a [lower] resolution would also help to minimize
> the run-time memory allocation which should make apps more responsive
> and generally perform better. I'm sure using a canvas element is not
> the most efficient way to resize images albeit I like your creative
> approach ;)
>
> Right :) I was merely trying to push back (gently) to see if we didn't
> have a simpler solution. I agree that there is value in controlling the
> options (though I'd rather see them limited, given the complexity that
> we can open up).
>
> > [NoInterfaceObject]
> > interface captureImageOptions {
> >   attribute unsigned long limit;
> >   attribute double duration;
> >   attribute unsigned short width;  // [0, 65535] should be enough?
> >   attribute unsigned short height; // ditto ("640k is enough for
> everyone" etc.)
> > };
>
> Writing the WebIDL is always going to be the easy part here :) Do
> devices support setting width and height independently? If not which
> one determines which resolution is chosen? How does one fallback? There
> are plenty of annoying details to sort out here.
>
>


Here's the Flash/ActionScript API: http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/media/Camera.html

They have a method: public function setMode(width:int, height:int, fps:Number, favorArea:Boolean = true):void

width:int - The requested capture width, in pixels. The default value is 160.

height:int - The requested capture height, in pixels. The default value is 120.

fps:Number - The requested rate at which the camera should capture data, in frames per second. The default value is 15.

favorArea:Boolean (default = true) - Specifies whether to manipulate the width, height, and frame rate if the camera does not have a native mode that meets the specified requirements. The default value is true, which means that maintaining capture size is favored; using this parameter selects the mode that most closely matches width and height values, even if doing so adversely affects performance by reducing the frame rate. To maximize frame rate at the expense of camera height and width, pass false for the favorArea parameter.


Nick

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Received on Monday, 7 December 2009 22:29:55 GMT

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