Pimoroni has a less expensive one (30 €), but still a lot. The DVI Sock only costs a few euros …

I don’t think you need to send any blank lines. You send all the odd lines, send a vsync signal with an extra half line, and send the even lines. Do some research into “interlaced video sync pulses”.

Great minds think alike, I have been thinking along these lines too! I have already built the Raspberry Pico based MMBASIC computer with VGA output, and it’s nothing short of fantastic! However the DVI-D (Pseudo HDMI) output takes the graphics capability to a new level! Of course MMBASIC doesn’t have to fully exploit the higher colour depth or resolution, but operating at 640×480 with say 64 colours would be pretty noice.

Now with that said, I foresee two immediate problems.
1. The VGA solution also uses the PIO pins, and then one of the cores is used for sprite management, frame buffering etc. I believe. At the very least there will be a code change required, at least to replace the VGA PIO implementation. As an API, I will be surprised too, if the interface between PIO (VGA) and the framebuffer core code is the same as the DVI PIO solution, but I may be wrong. Anyway, there will have to be a code change.
2. RAM. There’s not enough of the stuff, so higher res and higher colour depths will be a problem. But I think I have a fix. Use external PSRAM, and perhaps use one RP2040/Pico as the “GPU” and it has its own dedicated PSRAM connected. It then talks to a secon RP2040 that provides the “CPU” or brains of the system, running MMBASIC, and it can manipulate/move graphical assets around by instructing the GPU with minimal overhead (say over I2C link). I want/need this 😉

I’m interested in using it for an unique audio visual display purposes. Please, can anybody tell me:

Can you power the Pico through the HDMI cable, even if it’s on time broadcast side of the cable?

Can you set to Rec2100 colorspace (rec 2020 HDR colorspace)?

Is it possible to hook up extra lines to the HDMI, to send audio (and rec2020/HDR signaling)?

Can you output video through one of the USB video formats (video from unchanged Pico through a USB to Pico adaptor)?

Using the Pico wireless, can it do Miracast?

Can a regular bitmap video mode be done, and manipulated for game graphics with left over cycles?

Seedstudio does a mini RP2040 board. Can the HDMI interface board and software, work on that. They also have a RiscV version with wifi, so it would be good if it could recompile for that.

https://www.seeedstudio.com/XIAO-RP2040-v1-0-p-5026.html?queryID=31d59a67f7c148df996ba9c1bb7563e3&objectID=5026&indexName=bazaar_retailer_products

I am interested in gaming applications, like gaming watch use.

Any JavaScript minimal viable run time platform put there?

Sorry a lot to ask, but
Most interesting.

Thanks you.

1. PWM Pins will probably not have the timing precision you would like to have for video output (this is why we use PIO which has very precise timing). But why not try it 🙂
2. I assume that it should be possible to generate an Analogue AV output from the Raspberry Pi Pico. I doubt that the PWM will be “enough” for this (would be happy to hear anyone with more experience chime in on it!).
note that PWM is simply switching the signal on and off, while the resistor ladder used in the VGA board for example gives continuous signal levels. So for the PWM solution to work it must operate at much higher frequencies than is required for the actual signal. I’m also not sure how external hardware would react to the signal being PWM’d instead of a continuous analog signal.
Possibly it could be smoothed out using a very small capacitor, for which you would need to take appropriate calculations.
3. the helper VGA / DVI boards contain what is necessary (mostly resistors). You can look at the schematic and build your own setup on a breadboard possibly, I’ve seen someone do it for VGA.
That being said, we do ship internationally:
https://buyzero.de/products/raspberry-pi-pico-vga-audio-sd-expansion-board?variant=39412666335412
Pico DVI Sock @ buyzero.de shop