One potentially helpful piece of out of the box hardware is bunnie's NeTV, which has an fpga in an HDMI path. By default it does overlays on an HDMI signal but

One potentially helpful piece of out of the box hardware is bunnie's NeTV, which has an fpga in an HDMI path. By default it does overlays on an HDMI signal but with some FPGA rejiggering I suspect doing freeze frames ought to work. At least on non-drm'd HDMI signals. https://kosagi.com/w/index.php?title=NeTV_Main_Page https://kosagi.com/w/index.php?title=NeTV_Main_Page