MiSTer FPGA Forum

Hi, I am new in MiSTer FPGA, if my question is stupid, please forgive me.

I have saw many articles and YouTube videos, they all connect VGA monitor through HDMI=>VGA zero lag device, and mention that this is the best way to connect to a VGA CRT monitor.

My question is, Why not use VGA 15pin (from Digital I/O board) to VGA monitor directly? sync/signal doesn't match? other issue?

I’m not sure why some people are using that method but I use a VGA cable straight into a VGA monitor and it works fine providing that you have the .ini file set up to do so.

If you have an I/O board connecting VGA to VGA is the best solution. When you don't have an I/O board you can connect the MiSTer with an HDMI2VGA adapter to your VGA monitor and use the direct video option of the MiSTer firmware to send an analog video signal through the HDMI port.

This option was implemented in 2019 until then it was necessary to use the I/O board. The advantage of this method over the I/O board is that a 24bit colour signal is produced where the I/O boad produces a 18bit colour signal. But this is only interesting for cores displaying material with 24bit colour depth.

The disadvantage is that many DACs in cheap adapters don't produce full range RGB, you have to edit the Mister.ini to tell the MiSTer to use limited rage RGB.

https://github.com/MiSTer-devel/Main_Mi ... rect-Video

Another advantage of using an HDMI > VGA adaptor is that the audio DAC can sound much better than the I/O board's built-in audio.

The HDMI output looks better. The VGA output from the analog IO board is not as vivid, on any core. It is duller by comparison. That was my experience at least while my VGA monitor still worked.

thorr wrote: ↑Mon Aug 16, 2021 6:15 pm The HDMI output looks better. The VGA output from the analog IO board is not as vivid, on any core. It is duller by comparison. That was my experience at least while my VGA monitor still worked.

I have the opposite experience, but it really comes down to which converter you are getting, and maybe which IO board revision.

thorr wrote: ↑Mon Aug 16, 2021 6:15 pm The HDMI output looks better. The VGA output from the analog IO board is not as vivid, on any core. It is duller by comparison. That was my experience at least while my VGA monitor still worked.

Direct video with hdmi to vga adapter looks significantly better than using i/o board.

Are you sure you don't have a defective io board?? There is a lot of garbage suppliers out there that don't know how to solder a resistor array... That will cause your colors to be all over the place

thorr wrote: ↑Mon Aug 16, 2021 6:15 pm The HDMI output looks better. The VGA output from the analog IO board is not as vivid, on any core. It is duller by comparison. That was my experience at least while my VGA monitor still worked.

That’s certainly not the case with my set up.

thorr wrote: ↑Mon Aug 16, 2021 6:15 pm The HDMI output looks better. The VGA output from the analog IO board is not as vivid, on any core. It is duller by comparison. That was my experience at least while my VGA monitor still worked.

this was definitely not the case when using the v6.1 IO board I have, I found the opposite but I guess far to many other variables are present in either type of setup to give a definitive one is better than the other with consistency.

I have IO board, but did not get anything when connecting VGA screen on it. How do I enable it. Sorry for n00b question.

Direct video with hdmi to vga adapter looks significantly better than using i/o board.

Significantly better ?
What a load of garbage. That would suggest that the output of the I/O board is terrible, which is not the case. Infact, it's the complete opposite. I find it's better, and the increased saturation of the HDMI port is wrong, and not like original hardware.
Seriously, there is some utter crap posted on these forums.

SuperFrog wrote: ↑Tue Aug 17, 2021 1:14 pm I have IO board, but did not get anything when connecting VGA screen on it. How do I enable it. Sorry for n00b question.

MiSTer_Kirk wrote: ↑Tue Aug 17, 2021 2:38 pm

Direct video with hdmi to vga adapter looks significantly better than using i/o board.

Significantly better ?
What a load of garbage. That would suggest that the output of the I/O board is terrible, which is not the case. Infact, it's the complete opposite. I find it's better, and the increased saturation of the HDMI port is wrong, and not like original hardware.
Seriously, there is some utter crap posted on these forums.

Hostile much? Just because your experience is one particular way does not make it the truth for everyone. It is very interesting to me to see all the varied responses and great information to know that not all experiences are identical. I appreciate all the information and that people take the time to share their opinions. This is usually followed up by digging in and comparing ini files, hardware choices, etc. to get to the reasons for the differences and coming up with the best solution. Scaring everyone off from sharing their opinion by crapping on them accomplishes nothing.

In my case the image was dimmer (harder to see), not less saturated. I ended up trading for the digital IO board and use an HDMI to component converter that looks spectacular on my CRT TV's (they don't make these anymore and 99% of the other converters out there don't work with the MiSTer). It is good to hear that if my converter ever dies that going with the VGA I/O board will be a viable option and not necessarily be dimmer than what I have now if I get it from a different supplier.

No. You don't like my posts, then you are free to put me on ignore.

Spurred on from this post, I went and got an HDMI to VGA converter to try Direct Video out for myself. I personally can't make out an appreciable difference between the Direct Video VGA and the IO board VGA. If I had to say anything, I'd give the IO board output a point for looking ever so slightly brighter (screen contrast, not colors), but that could be just my brain trying to come up with a difference. I tried it on both my CRT and an LCD screen. I can't definitively give the advantage to either solution.

As has been pointed out, maybe it's because I've got a newer analog IO board. I bought mine from Ultimate MiSTer about 2 months ago so it's fairly new. But if not for my own curiosity, then I wouldn't have bought the adapter to use Direct Video mode. From my experience, there is no difference in using Direct Video over the analog IO VGA port. It could still be a viable option for someone piecing together a MiSTer on the cheap by starting with a base DE10-Nano over HDMI and getting the converter later for VGA. But I personally can't say it's worth giving up the analog IO VGA for. I like having my MiSTer hooked up both to my 4K TV and my CRT for whichever experience I'm more interested in and that I can take advantage of the GB and GBA 2P cores to use separate screens.

Basically, just use whatever works better for your situation.

I can't imagine a rabbit hole deeper than analogue image quality, so arguing about it all is a fairly pointless task. As somebody said above, there are simply too many factors involved.

One indisputable advantage of Direct Video is that it's a ~5 time cheaper solution, so there's that.

Everyone here who is saying that Direct Video looks worse than the I/O board VGA:

You may need to set "hdmi_limited" in the mister.ini file to a value of 1 or 2 (defaults to 0)
This will make a big difference to the image quality if not set correctly for your particular adapter.
You can test this by using the 240p test suite in SNES, and checking that your black/white levels aren't crushed.

The other issue is that the quality of HDMI > VGA adaptors can vary wildly. It's worth doing some research into which are recommended (either here or on the old www.atari-forum.com MiSTer section).

Lightwave wrote: ↑Fri Aug 20, 2021 6:09 pm The other issue is that the quality of HDMI > VGA adaptors can vary wildly. It's worth doing some research into which are recommended (either here or on the old www.atari-forum.com MiSTer section).

In case it's helpful to anyone, I just switched from the I/O board to Direct Video in anticipation of the PS1 core, and ended up using a Tripp Lite P131-06N as an adapter. It works beautifully without having to worry about "hdmi_limited" in the .ini file. Hooked up to a PVM 20M4U, so (if I read the manual correctly) the potential voltage problem on pin 13 that some adapters cause is not an issue for me.

As a side note, I truly wasn't expecting a boost in image quality since I was already so happy with the I/O board, but something about it seems noticeably better now. Something obvious enough for me to notice but vague enough that I couldn't tell you exactly what changed. I guess it looks . . . I don't know, crisper? Subjective opinion, so grain of salt.

hmmm i use the vga on the i/o board 6.1 straight into a vga crt monitor and have the audio rigged up to my sony amp. the picture is crystal and the sound is great - just like I remember it being.

Rotley wrote: ↑Sat Sep 04, 2021 2:20 am As a side note, I truly wasn't expecting a boost in image quality since I was already so happy with the I/O board, but something about it seems noticeably better now. Something obvious enough for me to notice but vague enough that I couldn't tell you exactly what changed. I guess it looks . . . I don't know, crisper? Subjective opinion, so grain of salt.

Because of a limitation in the number of GPIO pins, the VGA 15-pin on the I/O board is driven by a resistor ladder DAC with 6 bits of resolution per colour - for a total of 262,144 possible colours... inside the cores, the colours are calculated at 8 bits of resolution per colour - for a total of 16,777,216 (possible) colours... which is output to HDMI.

I can't say that this is clearly the reason, as it would require a particular type of image in order to be observed, but this is possibly the reason.

I have 2 different Mister, one with i/o and the other with Direct Video, both on CRT. If you see a massive difference between the two setup, you have big issues somewehere down the chain or is big time placebo, the biggest difference is indeed in the Audio output.

dshadoff wrote: ↑Sat Sep 04, 2021 1:20 pm Because of a limitation in the number of GPIO pins, the VGA 15-pin on the I/O board is driven by a resistor ladder DAC with 6 bits of resolution per colour - for a total of 262,144 possible colours... inside the cores, the colours are calculated at 8 bits of resolution per colour - for a total of 16,777,216 (possible) colours... which is output to HDMI.

The way Sorgleig talks about it I believe this is key. He makes it sound like there is no issue using 6-bit in most cores over the analog I/O because that is all those systems are capable of. Once you bring in the scaler and its shaders and interpolation (and maybe even scandoublerfx?) all bets are off though.

And the specialized palettes