[GEM-dev] 0.90 and pix_video under Linux

[Mirko Petrovich]

IOhannes m zmoelnig wrote:

>>>
>>> > Alpha blending doesn't work with pix_video using [alpha] and
>>> > [colorRGB]in the renderchain (it worked in 0.888-cvs).Should I use
>>> > [pix_alpha] instead ?
>>>
>>> hmm. i just tried and it certainly works for me.
>>> does it produce any result (e.g.: image dimming but no transparency) ? 
>>
>>
>>
>> Nothing but black.
>
>
> probably your [color]/[colorRGB] is set to black ? (or the 
> alpha-channel  is 0 ??)
> thinking of this, it might be, that the video4linux-driver is able to 
> produce RGBA-images but unfortunately sets the alpha-channel of each 
> pixel to 0. in this case, you will have to raise it manually. 

I checked this, and it's not the problem , the strange thing is that 
alpha works in pix_gray and even in pix_yuv (I get a distorted image, I 
guess this is right).

>
>
> if the whole thing is just about fading several streams, use 
> openGL-alpha blending instead of [pix_mix], so you don't have to care 
> about dimensions at all (so the only remaining issue would be, setting 
> the alpha-value of the [pix_video] to a decent value) 

I was calling pix-mixers (I forgot there was a pix_mix object) as a 
generic name, actually I'm using compose,add,subtract,diff,compare, 
chroma_key,mask, etc... and my idea was to fade the resulting image 
textured in a lot of geos (with openGL-alpha blending).

Thanks again

-- 
Mirko Petrovich
Santiago de Chile