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Re: Screen Overlay

Fri Apr 06, 2012 2:40 pm

First of all, I need to be able to buy my Raspberry

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Re: Screen Overlay

Mon Apr 09, 2012 3:07 pm

Perhaps you could use the Parallax propeller chip, (a microcontroller with eight CPU cores, and the ability to generate video signals) together with some fast opamps with three state outputs for the output mux, and a circuit to extract sync pulses from the life video input for syncing the output of the propeller video to the life video stream.

The propeller is probably able to synchronise the video it generates to the syncpulses it receives, and can control the three state inputs of the opamps to select which of the two signals to pass. It would probably also be possibe but very difficult to extract the colorburst signal, and synchronise the propeller video generation with it, but using monochrome color output (without the colorburst signal) should be doable. You can put your question here:

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Re: Screen Overlay

Tue Mar 29, 2016 1:36 pm

Have you seen this Arduino solution?

It uses the lm1881 to extact the sync and makes the overlay, potentially you could do the same with the Pi but I am not sure if you could get the same kind timing precision. It is all worked out already so you could actually just send the information you want on screen over serial to an arduino.
My Kickstarter for a analogue AV out -

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Re: Screen Overlay

Wed Aug 15, 2018 8:37 am


I have a very similar requirement for a project i am working on,, did you end up implementing this design? If so, can you please advise on your chosen method.


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