Overlay graphics on hdmi input

Which system do you use? Android, Ubuntu, OOWOW or others?

Ubuntu

Which version of system do you use? Khadas official images, self built images, or others?

Khadas official images

Please describe your issue below:

I want to overlay graphic clock over hdmi input, is it possible?
Are there examples about this ?
I read in the data sheet of the processor that there is a mixer function , but I can find how to use this function.

Post a console log of your issue below:


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