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overlay with two framebuffers

Question asked by Tamas Selmeci on Dec 5, 2013
Latest reply on Dec 18, 2013 by Tamas Selmeci

Hi all!

 

Having the following kernel parameters:

 

video=mxcdi0fb:RGB24,1920x1080M@60 video=mxcdi2fb:RGB24,1920x1080M@60 hdmi di0_primary

 

Writing bytes into /dev/fb0, I can see the pixels on the display, that's ok.

Writing bytes into /dev/fb2, I can't see the pixels.

 

cat /sys/class/graphics/fb0/name

DISP3 BG

 

cat /sys/class/graphics/fb2/name

DISP3 FG

 

So fb0 is the background and I suppose it covers the foreground pixels. I suppose somehow the alpha of background should be changed or color keying should be used to make the foreground also visible.

 

I'd like to implement an OSD and using multiple framebuffers (one with the video data, another one with the OSD itself) seems to be a convenient way.

 

How can I adjust the color keying/opacity of each framebuffer? Is this possible at all?

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