[PD] GEM problem with [alpha] on MacOS

[Mathieu Bouchard]

On Fri, 25 Feb 2011, Matteo Sisti Sette wrote:
> On 02/25/2011 02:41 AM, chris clepper wrote:

> I meant which object. I mean, if it is pix_video who "decides" which 
> color space to use (as opposed to the OS or somebody else outside GEM) 
> then I guess the same color space could be used by default in all 
> platforms. Or is there a particular reason to prefer rgba by default on 
> linux?

Maybe it's a matter of making OSX look more efficient than Linux ;)

In fact, the YUV-422 format used by GEM has only half the content that 
RGBA has. This is both because YUV-422 doesn't have an alpha, and because 
YUV-422 uses half-resolution in two of its channels : 1+½+½=2, whereas 
1+1+1+1=4. Naturally, when there's only half the amount of data, there's a 
lot less work to do.

But really, when I use GEM on Linux, I often have to use [pix_rgba], 
because GEM produces YUV pixels. I think it was in [pix_video]. It depends 
on the camera.

> I think all unnecessary differences among platform should be avoided 
> even in default values (otherwise one is obliged to set everything 
> explicitely)...

This is a topic that comes back often for GridFlow...

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