This isn't about portable gaming, but I thought it'd be worth throwing it out here as it's definitely a related task. The project is a small pocket monitor for film & TV work in remote locations.
So, I would like to find a way to display an HDMI image on a small TFT (or possibly OLED) display, perhaps 2-4 inches in size. The HDMI picture would be in one of the usual television formats (720 50/60p, 1080 24p, 1080 50/60i).
The "right way" to do this is to buy one of those small AMOLED panels that are used in smartphones, and develop a controller board for it with HDMI input. Despite the FAQ on this forum, this is possible (well, obviously it's possible), but you'd have to have some background in FPGA development. Pros: Good image quality, small. Cons: a huge technical challenge as the FAQ on this forum correctly states. I probably could do this, but what a pain.
The "quick way" to do it is to convert the HDMI to composite and use a display that has a composite input, or at least one for which there is a composite input controller board readily available. Pros: Quick, easy. Cons: Some HDMI devices don't like all of the display modes I might need. Also, crap pictures: at the upper end of the size range - 3.5" and above - there are TFT and OLED panels which have enough pixels to make HD resolution meaningful. Also, there are compatibility issues with HDMI downconverters, and they're big for a portable project, and they consume a lot of power.
The only intermediate option is something like the Olympus VF-2 electronic viewfinder, which appears to be a very small display, perhaps one or two inches, with what several commentators believe to be HDMI input. There are commercial options in the US$700 plus range, which is a bit rich for my blood.
Does anyone have any thoughts? Are there any other small devices that have HDMI inputs? There are a million embedded devices about with small TFTs in them, but I really don't want to go through developing a TFT driver board if I can possibly avoid it.
Thanks for any ideas.