HDMI Pass-through Overlay help needed

Question

I am trying to create/find a way to pass HDMI signal through to overlay information on a television/monitor whilst still watching tv programs in the background. I'm not sure what to search as when I use google I just find Xbox pass-through or streaming information. I'm basically want to be able to pass caller ID and smart home information to display on the television and help would be much appreciated.

Fred27 · Answer

Here's a good example of exactly what you're after - also using Xilinx hardware: https://www.hackster.io/news/microzed-chronicles-hls-overlay-generation-8bb28ed7a536 Be warned though - it's not exactly beginner stuff.

shabaz · Answer

Just thinking, although you've specified a specific method (HDMI overlay), if actually that's just an example and you don't mind a different implementation to reach a similar-ish end result, then there's another option - it won't work on all TVs though.

Since a lot of TVs are now 'smart TVs' you could investigate what options there are for using code to interact with the TV. Even if the TV is not smart, there are HDMI sticks to enable that (Amazon Fire etc).

An example method might be one of the video or picture casting methods, although they will take up the entire screen. If you're have Android built-in to the TV then it is even easier, since you can write a custom app. Or, there are ready-made apps like PiPup. If you install it to your TV then you send custom messages using HTTP and it will appear as an overlay in a box in the corner.

beacon_dave · Answer

You may need to consider HDMI signals with HDCP copy protection enabled, along with maximum video resolution and frame rate, embedded audio support etc., as they will likely complicate matters. If you want to simplify things, then you could use the likes of a broadcast titler box such as the DataVideo TC-100 https://datavideo.com/eu/product/TC-100 Your SBC would then only need to generate the overlay information and output it on HDMI and the titler box would then take that signal and overlay it onto the live video. Some video scalers with PiP like the Kramer VP-461 https://www.kramerav.com/product/vp-461 also offer luma key functionality, so depending upon your requirements may be worth considering.

beacon_dave · Answer

Or perhaps use something like a R-Pi TV Hat and do the overlay there. There was an Element14 Presents episode using a TV Hat as a DVR solution recently: Episode 444: Raspberry Pi 4 DVR

HDMI Pass-through Overlay help needed

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