[spicyjpeg]

It's worth mentioning that HDMI encoder chips are actually quite difficult to get hold of as a hobbyist; the HDMI association prohibits their sale to anybody who has not signed the relevant NDAs, paid membership fees and whatnot. The project shown here gets around this by using a freely available DVI encoder chip instead, which works fine (the HDMI specification mandates backwards compatibility with DVI) but lacks support for a number of HDMI-only features such as audio and higher resolutions.

The only HDMI encoder I have seen so far with easily accessible (i.e. leaked) documentation is the CAT6613/IT6613 from ITE, which also happens to be available for purchase in single quantities from a number of Chinese retailers. It seems to be used in the OSSC and several FPGA development boards, so it's about as close to being an unofficial standard for open source projects as it could be.

[raphlinus]

This is a good reason to bit-bang the protocol. It is in fact possible to get HDMI including audio out of an RP2040, as is demonstrated by infones[1], a NES emulator.

[1]: https://github.com/shuichitakano/pico-infones