MiSTer FPGA Forum

Hello, first post here - hi all

The idea is to get the Mister and a good HDMI to VGA adapter to use the Direct Video feature without the I/O board.

Now:

- Is it possible to use the analog audio output on the HDMI adapter in Direct Video mode?
- In the standard 15khz CRT mode, can I use the usual VGA to SCART cable I used so far with the Raspberry Pi/VGA666?
- For connection to a 31khz VGA monitor, it seems that scandoubling is preferable to the 120hz 240p mode because it bypasses the scaler. Do non-standard refresh rates (the usual PAL, R-Type, Mortal Kombat etc) still work properly that way? Also, what's the best way to add 'fake' scanlines in this configuration?

Thanks,
AF

Hi, welcome

- As it is mentioned in the wiki, the direct output mode uses HDMI adapter to pass a non standard signal so I'm not sure you can do that (I may be wrong, but I tested with mine, it doesn't work).
- I'm not familiar with this specific cable, you can use any VGA to SCART adapter but some need the sync to be rewired (it's very easy, you need to swap 2 pins on the SCART connector, no soldering needed), BUT, be careful if you use it with a HDMI/VGA converter, you need a 470 Ohm resistor on that pin if you plan to use it on a CRT (see the wiki for the technical details)
- I play a lot with a PC CRT monitor, the scandoubler works really well with any 240p I tried, but sadly it doesn't work with 480i signals (for example when I play Sonic 2 on the Mega Drive, the screen turns off when the demo plays 2P mode)

That said, I strongly recommand you to buy a analog I/O board in your case, it's way easier and will save you from a lot of head scratching time.

I/O board is much more expensive, and there is really no "head scratching time" with Direct Video, or at least no less than you'd have with I/O board. You can always get it later anyway.
If you get a DAC with analog output, it will work. You'll need a cable with a separate jack though.
About that 470Ohm resistor, it's probably better to put it on, but I've been using a cable without it for nearly a year now (with a 15khz Trinitron) and it's been fine. YMMV.

Hi, I use direct video exclusively.

Yes the audio output from the HDMI converter works.

I've never bothered with the sync resistor either. In fact the manual for my Ikegami monitors say the upper rating on the sync signal is 6V.

Hello,
I was discussing this in shmup forum. Soon I will buy a iiyama pro 454 for cheap, i also own a bvm 20f1e. In my bvm i am with direct video mode, and it works very good.
With the iiyama crt i am mixed feeling about the scandoubling option. Less scanline, and in my memory vga crt at 60hz are a pain for the eyes. Maybe my memory is wrong though, that's what they told me in shmup forum, but men i remember how hard i hated to watch all these pc crt screen and their horrible 60hz, i had every time to go in windows display option and put it at at least 85hz...
So i would prefer 240p 120hz to 640x480 60hz.
Anyway, if i understand the problem with the scaler is that it had some frame of lag. Not sure if it's really noticable, but i guess it's still better if you avoid it. The question is, do we really need the scaler to simply double the frequency, maybe to have this option in the mister.ini would be nice, like the scandoubler option do in direct video ? A double or even triple the frequency (a lot of crt seems to support up to 200hz, so 240p 180hz would be possible i guess).

Well, that's intersting, because now I know that my HDMI to VGA adapter is not working properly, thanks guys.

Malan wrote: ↑Thu Apr 08, 2021 4:08 pm Well, that's intersting, because now I know that my HDMI to VGA adapter is not working properly, thanks guys.

How so?

Atomidy, what I can tell you is that I also remember perfectly 60hz being horrible, but I ran 640x480@60 on the Pi lately and it's not bad at all. I think it's more at 1024x768 and upwards that it becomes unbearable.

Atohmdiy wrote: ↑Wed Apr 07, 2021 1:29 pm Anyway, if i understand the problem with the scaler is that it had some frame of lag. Not sure if it's really noticable, but i guess it's still better if you avoid it. The question is, do we really need the scaler to simply double the frequency, maybe to have this option in the mister.ini would be nice, like the scandoubler option do in direct video ? A double or even triple the frequency (a lot of crt seems to support up to 200hz, so 240p 180hz would be possible i guess).

I'd also love a framedoubler but I'm guessing its far more tricky. You would need a buffer to store the full rendered frame for one so it could be repeated, a lot more space than just a single line, and that kind of thing is usually the scaler's job... might be more plausible to see a new vsync_adjust mode that is like vsync_adjust=1 but just doubled frames. Still will have a little lag though, albeit less than vsync_adjust=0 with most cores not running at exactly 60hz...