405 lines from Raspberry Pi 5

[ppppenguin]

I really wouldn't bother with the DAC08 for video. An R-2R ladder is fine (probably better) and there's no problem with DC offsets. Choose the resistor values so it can be easily driven by the logic. This will need to be 74HC, 74HCT or a FPGA. (There's been a recent discussion going on elsewhere about deriving analogue video from logic. People are being a bit precious about it. For 3 or 4 bits you can do just about anything and it works reasonably. Though much better to use HC/HCT than LS etc. I know, I've done it)

The screenshot is the DAC in the Aurora. It's driven directly from a Xilinx 3 series FPGA. It shows very close tolerance resistors for the more significant bits. In practice resistors from the same batch of 1% parts will often be closely matched. Or match them with a DMM. The absolute value doesn't matter. You can use pairs of 1K resistors in series rather than separate 2K. Easier to get the match that way.

The odd looking values on the LSBs are a clever trick that Darryl used to make a 10 bit DAC using PWM for the low order bits. This technique, taken to its limits, gives you the 1 bit DACs commonly used for 16 bit audio. Not practical to go that far for video - the clock rate would be in the GHz range.