PSA - Some DACs don't work well with super resolutions

[BuckoA51]

These days lots of projects are using so called "super resolutions", which are resolutions like 2560 x 240. These are designed for use with CRTs, either directly if your hardware has analogue out, or via a DAC. Mister, GroovyMAME, CPS2 Digital and OSSC Pro all can make use of them.

I'm making this little PSA to let you know that some DACs do not like these super resolutions. Specifically the HD Fury 3 does not like them (HD Fury 2 is fine though). Obviously, there might be others.

Running super resolutions through HD Fury 3 results in a bunch of smeared extra pixels at the edges of graphics, here's an image to illustrate it.

neogeo-hdmi-crt by videogameperfection, on Flickr

[Gunstar]

Do you know what firmware is running on your HD Fury 3? I wonder if the Neo JailBreak fw would help in any way

[BuckoA51]

I was unaware that even existed, thanks, I'll give it a try when I get a moment.

[Josh128]

Interesting, thanks!

[KuroHouou]

Lots of questions here as the HDFury has been proven by many people to be an awesome DAC.

1. Can you list the entire chain of devices/software/cables involved in getting the signal to the CRT?
2. Are you on the latest firmware for the HDFury3?
3. What other DAC's might you have available to test to confirm with?

[kitty666cats]

This fella has done extensive testing with HDMI to VGA DACs on MiSTer direct video and the HDFury 3 worked fine for them. Not only that, but it (and the HDFury X4) were the most color-accurate out of all the DACs they tested.

Could be the firmware, could be the source device, or even possibly the version of the HDFury…? There’s black and white HDFury 3’s, maybe one’s an earlier revision and slightly different? Or could just be a partly faulty unit.

Anyway, here’s the HDMI to VGA DAC analysis, and the 2nd link is their tests for color accuracy:

https://docs.google.com/document/u/0/d/ ... obilebasic

https://docs.google.com/spreadsheets/u/ ... A/htmlview

[BuckoA51]

Thanks for the replies everyone, again Shmups is the best place to discuss AV issues by far! To answer lingering questions and elaborate further:-

The source was OSSC Pro and CPS2 digital as installed in a AES. Obviously those share similar code base. My Mister and my Groovy Mame PC aren't connected by HDMI at the moment so can't easily test them.

The HD Fury 3 is a black one purchased I think around 2 years ago from an official HDFury reseller.

Changing source devices to DVI output mode cured the problem (suggesting either DAC misinterpreting HDMI data or quirk in how these devices generate super resolutions)

Swapping the HD Fury 3 out for the HD Fury 2 along the same signal path everything works fine (strongly suggesting it's not something e.g my HDMI matrix is doing)

Firmware is whatever it shipped with, so I will definitely try that Neo firmware and report back.

Edit - Oh people asked for the entire video chain.. it was OSSC Pro (or CPS2 digital) -> HDMI Matrix -> HD Fury 3 -> Mitsubishi XC-3730C multisync

[BuckoA51]

Ok, updating the DAC firmware didn't solve it. At this point I need to do a more thorough investigation, but people please be aware there may be compatibility issues between HD Fury 3 and OSSC Pro/CPS2 digital.

P.S - Forgot to mention above but same video chain but using OSSC Classic in 240p pass through mode works fine with this DAC/CRT combo.

[KuroHouou]

I think it’s best to try and narrow down the links in the chain first. Have you tried taking out the HDMI matrix switcher? I know you said it works fine with the HDFury 2 but that is a very different device that doesn't even support RGBS. Just worth a shot.

Also you say OSSC Pro or CPS2 digital. Curious does that mean that each individual device doesn’t work regardless of source? Are you sending Suoer Res out the OSSC Pro by itself? not sure why you would be using the OSSC pro into a DAC, assuming if you had an analog source going into the OSSC pro you wouldn’t convert it to digital only to go back to analog (unless your doing some downscaling). Just trying to understand why an OSSC pro is in this loop?

That said for the CPS2 digital, is it sending the super resolution directly into the HDFury? Not familiar with those devices actually. It very well could be an issue with the super resolution being output from the source device, the dvi 1.0 and HDMI 1.4 specs should be compatible between the two.. but if dvi mode is working and HDMI isn't, it leads me to believe it's the source device sending a signal that is even more out of spec then Suoer Res already is.

Do you have any other DACs you could test as well? The HDFury 2 is really meant for PC monitors as like I said it's RGBHV, which I think your monitor supports. So curious how another RGBS DAC would work. In this scenario.

[BuckoA51]

It's certainly a strange one, OSSC Pro was basically in that chain just for testing. Usually yes, you'd go straight from the HDMI AES (containing the CPS2 digital board) to the DAC and then into your CRT.

RIght now I found that putting the OSSC Pro between the output of the CPS2 digital and the DAC makes things work, which points me to some quirk in the CRT output modes of the CPS2 digital mod, but I need to investigate more. Folks on Twitter say they're not having any issues with HD Fury 3 like this so that certainly points back to me and something in my setup.