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Comment by peterburkimsher | Hacker News Reader

This may be a long shot, but is there someone here who knows about HDMI video freezing? I'd like to design a freeze button, like in some projectors, as a separate hardware accessory. Plug in HDMI input and output, then press a button to change between pass-through and freezing the last frame.

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This is doable with the right hardware. You'd need HDMI decoder and encoders and enough internal or external memory to buffer the resolution you are working with. (1080p = 1920 x 1080 x 3 = 5.9MB) You can probably avoid having to double buffer if it waits for vsync to switch modes.

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

The minispartan FPGA devboard has HDMI in- and output and is decently priced. On the other hand, I don't think it is fast enough to process full hd (only hd, so 1280x720).

See http://hamsterworks.co.nz/mediawiki/index.php/FPGA_Projects for many examples (also using different boards).

Edit: Just realized that storing a single frame needs quite some memory. This is something you need to keep in mind. If you use the DDR RAM on the board you'll probably be find, but this is not trivial (even using the tools designed to do this).

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