[GEM-dev] pwc problem / help appreciated

Mathieu Bouchard matju at artengine.ca
Fri Sep 21 20:06:16 CEST 2007


On Mon, 17 Sep 2007, Roman Haefeli wrote:

> 1) the probably more obvious solution would be to implement all pwc
> specific features into [pix_video], so that all these settings can be
> set from within gem. besides that it seems very awkward to implement
> driver specific options in [pix_new], it is probably also a lot of work.

In GridFlow, you can access about half of the pwc-specific features, and 
you can see them in the [#camera] control panel. The values of the control 
panel can be recovered through the right inlet if you send a "get" 
message, e.g. a "contrast $1" message is emitted, where $1 is a number in 
the range 0..65535.

On some camera drivers, using pwc options crashes the driver in some way. 
So you have to check in some way (how?) that you have a pwc camera, or 
have this as an option to the user.

> to the interesting point: if [pix_video] would send a 'restore' signal 
> to the pwc driver, whenever rendering is turned on (is the same as 
> 'whenever [pix_video] accesses the cam, right?). this would mean, that i 
> could set all required settings beforehand using 'setpwc' with the 
> option to save all settings into non-volatile ram.

It's much easier to interactively test the camera and modify options at 
runtime than to try to use setpwc, which is why solution 1 is much better.

E.g. I've made a patch that gives feedback on the colour balance, which is 
better than automatic colour balance, because you can do things like 
specify a region of the image that you want to balance, ignoring the rest 
of the picture (e.g. balance colour only according to the brightest or the 
most vivid colours). I could have made that patch run fully automatically. 
That's the kind of thing that setpwc can't do for you.

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| Mathieu Bouchard - tél:+1.514.383.3801, Montréal QC Canada


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