MiSTer FPGA Forum

Everyone seems to mention CRT being a lot better than HDMI from a latency point of view. I have no interest in a CRT as they are just too bulky for me. However I have just been offered for free a 4:3 LCD monitor with VGA input and wondered if this is much better than my current LCD with HDMI. However it would also mean me changing from a Digital IO board to an Analogue one (otherwise I would just test it out for myself)

This is probably a stupid question but I don't know if the analogue boards are specifically for CRTs or whether they still offer a significant improvement with a LCD with VGA input.

you wouldnt swap. you would get a HDMI to VGA adaptor.

FPGA64 wrote: ↑Tue Jul 05, 2022 6:44 pm you wouldnt swap. you would get a HDMI to VGA adaptor.

Isn't that then converting a digital signal to analogue and hence adding latency?

Stick with what you have unless you have a strong preference for 4:3 with no borders. Digital (HDMI) will be better when screen technology (LCD) is the same or similar.

Mister can output direct analog video thru HDMI port. The device he is talking is a pinout adaptor not a signal converter.

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

Thanks everyone. I still don't know if there is any real latency difference between the two though. I don't really want to accept the monitor and then end up getting rid of it. I don't really have a lot of space for another monitor so I'm really only interested if the difference is significant.

There is no latency converting from HDMI to VGA with the MiSTer. The only place you need to worry about latency is within the monitor itself. Whether it is VGA or HDMI makes no difference. You need to look at the specs of the monitor. CRT's have zero latency. Anything else has at least some.

The older 4:3 analog input LCD is very likely to be worse in every way compared to a more modern LCD. There is no advantage to using VGA instead of HDMI if the outputs are both to an LCD as opposed to a CRT, where it would make a difference.

(If you prefer the 4:3 form factor, that’s of course a valid reason to get one!)

The big reason to use CRTs is that the display technology itself usually has no lag; from signal to display is typically nanoseconds. In effect, a console directly couples itself to the output beam, so there's no additional output delay beyond speed-of-light limitations.

All LCDs have lag, a distinct period of time between when a signal shows up at the external connector and when it shows on the display. Good modern LCD screens can react within a few milliseconds. But an LCD that takes a VGA input will probably be both old and cheap, and thus quite slow, and then will be slowed down even more by converting from VGA to the native digital signal.

So the offered monitor is very likely to be worse than what you already have. The screen itself will be slower, and then the VGA-to-LCD conversion will probably slow it down even more. You could easily be looking at 50ms lag or more. (three or even four frames.) And depending on the quality of the scaler, you may get substantial blur in the output.

tl;dr: Sending an analog signal to a digital device can't improve display reaction time. At best, the lag will be unchanged, and you would hardly ever see that happen. At worst, it could be really clobbered, and that's your most likely outcome. If the output is digital, drive it with a digital signal for best results.

So this is something that is objective but kind of subjective. Is there a difference? Yes. HDMI does introduce a bit of latency just by being HDMI. Is it significant? It depends on your own sensitivity to lag and the displays you're using.

In the early days of getting my MiSTer, I did some side by side testing out of my own curiosity. I compared my 4K TV over HDMI to an average LCD monitor and CRT TV using a VGA converter to composite with VGA pass-through. 3 different screens all through the same MiSTer. While MiSTer is impressive even over HDMI, the side by side did show it was still ever so slightly behind the analog VGA output. And it took a photo finish to really see the difference between the LCD and the CRT. Now, there are some things different today than back then. For one, I've since learned about the low latency settings in MiSTer and I can natively hook up a CRT TV instead of using a converter. The results may be closer or potentially the CRT still slightly ahead.

With my current connections and settings, the differences are not anything that bothers me personally. The nostalgia of using my original Commodore 1702 monitor for the consoles or an old computer CRT for the AO486 core means more to me than just using a random LCD screen. But some people appreciate having a dedicated corner with a MiSTer and a monitor. Modern LCDs and sound systems are cool and all but there is something to be said for using a setup more in line with past experiences. The speakers I have for the CRT monitor are nothing special and the limited sound quality actually lines up with my old memories so I oddly enjoy it. Whether or not you'd feel the same, that's a question you'd have to answer yourself. Also to make sure it's clear, the VGA port is not just for CRTs. Works for both CRTs or LCDs. It's just a connector that can be set to be VGA, Component, SCART, etc.

Thanks for everyone's input. My conclusion from everything that has been said is there is little point in using a VGA output unless it is to a CRT monitor. So I would actually be better off sticking with my HDMI output to a modern LCD.

DevilHunterWolf wrote: ↑Wed Jul 06, 2022 5:45 am So this is something that is objective but kind of subjective. Is there a difference? Yes. HDMI does introduce a bit of latency just by being HDMI. Is it significant? It depends on your own sensitivity to lag and the displays you're using.

It's not HDMI itself that has the lag, it's the device on the other end. (plus, potentially, the generator *of* the HDMI signal, but in the case of the Mister, there's no lag there.) A high quality modern display will often have less than 5ms latency if configured for 'game mode'. If you display a CRT and that TV next to each other on the same signal, the LCD will be about five milliseconds behind, but you're gonna have a very hard time seeing any difference. They'll feel pretty much identical.

Older LCDs were often terrible. I had a Dell 2407 that had like four or five frames of lag. There may still be example videos up on Youtube. It had awesome display quality for the year it was shipped, but the latency was crazy high.

Fuzzball wrote: ↑Wed Jul 06, 2022 8:29 am Thanks for everyone's input. My conclusion from everything that has been said is there is little point in using a VGA output unless it is to a CRT monitor. So I would actually be better off sticking with my HDMI output to a modern LCD.

That is exactly correct.