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Altera_Forum
Honored Contributor I
893 Views

Overlay moving (live) graphics feed on video

I need to mix a live graphics image (Streaming into the FPGA) that has a special pixel value in places where VIDEO should show through. I know that the Alpha Blending Mixer can do this, if I can sample the graphics stream and create an ALPHA Channel with it. 

 

I need to see how to use the alpha channel (I can't find any examples) and use this data to enable the underlying video to overlay the graphics on a video stream. 

 

Thanks, in advance. 

 

Mike
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3 Replies
Altera_Forum
Honored Contributor I
37 Views

try this for liminance. 

 

output = pixel/256 *(256-alpha) + graphics/256 *alpha 

 

As for chrominance - good luck. It might be easier to convert it all into the RGB colour space before mixing if you want to mix in colour.
Altera_Forum
Honored Contributor I
37 Views

 

--- Quote Start ---  

try this for liminance. 

 

output = pixel/256 *(256-alpha) + graphics/256 *alpha 

 

As for chrominance - good luck. It might be easier to convert it all into the RGB colour space before mixing if you want to mix in colour. 

--- Quote End ---  

 

 

Thanks, but I need ti create the alpha channel and I also need to see an example of how to connect the alpha channel in SOPC.  

 

MIKE
Altera_Forum
Honored Contributor I
37 Views

have the same problem: 

i need to configure alpha blending on DE2 without using CPU 

 

I've found some information about Alpha Blending Mixer over google with next request: 

alpha blending mixer sopc example 

but in every manual NIOS processor is used 

 

does anyone have sth much useful, like working examples?
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