Creating composite / overlay video

[tlharris]

Hi there -
I've been using uControllers and a video overlay board (http://www.decadenet.com/bob4/bob4.html) to do simple overlays, but am interested in moving to a RPi to get HDMI quality.

The output is pretty simple stuff - data collected from sensors and output as serial data that needs to be formatted and overlaid. 4 or 5 fields.
I've seen graphic screens developed (HUD-type stuff for games, etc.) but haven't been able to find any info on overlaying onto a video stream. Lots of mention of different API's and libraries, but I'm afraid I don't know where to start.

I'm more comfortable with code, not a complete klutz when it comes to the electronics (but still learning) and would appreciate any pointers just to make sure I'm headed the right way.
Thanks in advance!
Todd

[ghans]

The Pi has neither HDMI nor Composite input.
USB based digitizers do not work well (if at all).


ghans

[OtherCrashOverride]

In *theory* you could stream the h264 output of a HD camera to the RPi over the network port. Then the RPi can decode it through openmax to an egl_image (as done in hello_videocube sample). After that it is possible to assemble a scene of arbitrary overlay complexity using opengl es. You could also use the dispmanx api layer to composite in realtime although there is no documentation for dispmanx.

Edit: It would also be possible to achieve this goal using the to-be-announced RPi camera board instead of an external HD camera.

[ghans]

Well , only if you can connect that camera to the Pi at all.
That leaves the foundations camera (25$) and HD network
cams ($$$).

ghans

[tlharris]

OK, guys... thanks for the input. It is as I was afraid of.... this is a much bigger bite than I'm able to swallow at this point.
So far, I'm thinking that the RPi piece is pretty straightforward - all I'd need to be able to do is to create the overlay graphics themselves. The tricky (read : $$$) part is probably taking that signal and combining it with the live video feed downstream using a video production switcher/keyer. These start at several $1000's and go up quickly.

Ah well.... I'll keep noodling on it.