Cool hack, but the part about the cost of off-the-shelf solutions is wildly wrong - Blackmagic's HDMI capture solutions can be purchased for less than 145usd for pci-e and 200usd for usb3 and they have free drivers&sdk for linux.
However our reliability requirements may be different than yours & the OP's, as we (at http://stb-tester.com ) use video capture for automated UI testing so we need rock-solid reliability.
I concur with the other commenter that devices with an upstream driver --such as the UVC driver-- are the way to go.
I've personally seen 4 red rockets die. considering the price at the time, for what was basically a glorified jpeg2000 decoder, it was bollocks.
https://github.com/jp9000/obs-studio/tree/master/plugins/dec...
Could you recommend a Blackmagic product supported by your plugin that can capture from HDMI (cheaper the better, I plan to use it for hobbist-level capture of desktop/games)?
Apart from possibly needing an update to the kernel package, all of the DeckLink devices are supported by the same SDK, with only some small variations (like giving the user the choice of selecting which input connector to use or similar).
I used the Intensity Shuttle for USB 3.0 on a Macbook (OS X) to develop the plugin. It costs $190 and works pretty well, but can't capture 1080p @ 60fps (only 720p/1080i). I only got it because I couldn't install a PCI-e card on my laptop ;)
If you need 1080p @ 60fps, the Intensity Pro 4K is also $190 and is a PCI-e card. Otherwise, the Mini Recorder should work just fine.