NeoVGA: Lagless, pixel-perfect line doubler for Neo-Geo MVS and AES

Joined
May 23, 2008
Posts
30
I think the board could definitely be built for under $40 itself, so if anyone designed a board for it / helped touch it up to be a little more stable then it could definitely compete with the currently available scalers in price. The installation isn't difficult, it's just tedious. If I have some time this week I'll neaten up my code and make some more changes (I've learned a lot more about VHDL since I started this project!) and if someone wants to work on it then that's great.

Would totally buy for whatever gives you a nice profit with the ~$40 per built price. Also i'm kinda shit for building circuits from scratch but could easily install it...
 

mikejmoffitt

Mickey's Coach
Joined
Feb 6, 2014
Posts
578
Haven't really had much time to work on it at all. I want to do a full rewrite, the original code is pretty ugly. I might be trying to make a general purpose video-oriented FPGA board soon, so if I make something like that I will be sure that NeoVGA can run on it.
 

marqs

n00b
Joined
Nov 6, 2014
Posts
2
Yep, got them mixed up - I've never touched one before so it was bound to happen.

DVI output would be nice, I just don't know how complicated it would be to do the TMDS output from the FPGA. The timings should match up so it may be a possibility. Unfortunately HDMI is a no go because it's expensive to legally use it. A DVI to HDMI adapter would sidestep that issue, though.
Very interesting project, keep up the good work!

Have you thought about using a DVI transmitter IC connected to the FPGA? I've been doing a bit similar project (analog video digitizer & scandoubler), and used a HDMI TX IC with good results. The only issue I can think of is compatibilty with some displays, as doubling vertical (and possibly) horizontal resolution may result into a mode which is too far from standard modes, and then not displayed correctly or at all.

That probably is more likely to happen with HDMI-only TVs than on desktop monitors with real DVI - for example my Panasonic plasma accepts only +-2 line variation, so only 262/263-line video using linedoubling would be detected as 480p (525 lines nominally) and displayed. Is Neo-Geo's output really 264 lines as you mentioned in the first post? All old consoles I've tested draw either 262 or 263 lines in 240p mode, and this page lists Neo-Geo's output also as 262 lines.
 

mikejmoffitt

Mickey's Coach
Joined
Feb 6, 2014
Posts
578
Very interesting project, keep up the good work!

Have you thought about using a DVI transmitter IC connected to the FPGA? I've been doing a bit similar project (analog video digitizer & scandoubler), and used a HDMI TX IC with good results. The only issue I can think of is compatibilty with some displays, as doubling vertical (and possibly) horizontal resolution may result into a mode which is too far from standard modes, and then not displayed correctly or at all.

That probably is more likely to happen with HDMI-only TVs than on desktop monitors with real DVI - for example my Panasonic plasma accepts only +-2 line variation, so only 262/263-line video using linedoubling would be detected as 480p (525 lines nominally) and displayed. Is Neo-Geo's output really 264 lines as you mentioned in the first post? All old consoles I've tested draw either 262 or 263 lines in 240p mode, and this page lists Neo-Geo's output also as 262 lines.

A DVI transmitter might be a good idea. I really don't know much about TMDS but I do know that I'm not yet skilled enough to get something so fast working stably. If there's a good integrated solution that I can basically just pass normal VGA-timing pixel data and have it transcode it into a usable DVI output, then that would be a great solution.

Licensing for producing and selling electronics is apparently complex, so if this project gets finished I'll likely just open source it as mentioned before. I may make some PCBs and sell them, but I don't think the market is big enough for it to do a real fully produced project.

Once I am finished with this semester (definitely the hardest so far - DSP is complicated!) I can maybe do some more work on this project including a clean re-write, and then open source it.
 
Joined
Nov 5, 2014
Posts
12
Great writeup. Very interested in the project and would love to see a few boards built to sell. I wish I had this kind of tech knowledge. I would definitely tackle the soldering to install on my mv4. Hope to see more
 

mikejmoffitt

Mickey's Coach
Joined
Feb 6, 2014
Posts
578
I got a new dev kit, a much easier to use Spartan 6-based one. I can actually use a modern version of ISE that works properly and compiles a lot faster. Hopefully this can help speed up creation of a new design. I can definitely build a prototype PCB around it, as it's a DIP socket board that can just mount inside a test PCB. For the DAC I will probably just bandsaw the original DAC out of a FUBAR MVS board I have and use it as-is so I don't waste any time on that!
 

Warpedflash

Crazed MVS Addict
Joined
Aug 6, 2010
Posts
142
I would love to have a version of this that could be made to fit into the AES's case. Looking great as a project!
 

fluxcore

Another Striker
Joined
Nov 4, 2013
Posts
324
Hrm, does the spartan 6 base then raise the price a bit? Or is it just part of the dev process?
 

mikejmoffitt

Mickey's Coach
Joined
Feb 6, 2014
Posts
578
Hrm, does the spartan 6 base then raise the price a bit? Or is it just part of the dev process?

It's for the sake of dev. It might raise it a little bit, but it's an actively manufactured part. The dev kit itself is $60 and about the size of a big flash drive, so I'm pretty confident the final thing can be a similar size. It should fit inside an AES.
 

massimiliano

ネオジオ,
20 Year Member
Joined
Feb 27, 2004
Posts
3,224
yep, super-interested too, keep up the good work!
 

fenikso

Slug Flyer Pilot
15 Year Member
Joined
Oct 6, 2004
Posts
3,932
I'm also watching this project with great interest. I think it's a fantastic idea.
 

Niko

Whip's Subordinate
Joined
May 15, 2014
Posts
1,773
I think OP gave up. Last I checked ( a few weeks ago ); Source still wasnt available.
 

mikejmoffitt

Mickey's Coach
Joined
Feb 6, 2014
Posts
578
I didn't give up, I'm working on things that need a lot more of my attention right now, mostly my game which finally got accepted onto Steam. Between that, finishing up my sound engine, working on another scaler project and various university assignments, I don't have a lot of time for this one just now.
 

massimiliano

ネオジオ,
20 Year Member
Joined
Feb 27, 2004
Posts
3,224
Darth-vader-hal-hefner-devil-horns-dio.jpg
 

Elgen

New Challenger
Joined
Jun 3, 2012
Posts
63
Just a quick post to subscribe...
Fantastic project };-P
 

SmokeMonster

Morden's Lackey
Joined
Jan 25, 2014
Posts
365
Incredible work Mike. I'd love to have a generic line-doubler to use with other consoles, something along the lines of a GBS-8200 but with better processing.
 
Joined
Jan 23, 2015
Posts
1
What's up guys, I've had my eye on this project since I got my mvs a few weeks ago.

Am I right to assume that pretty much all of the timing can be figured out by using negative edge caused by the "vertical blanking" interrupt?

If you wait for that negative edge which supposedly falls right in the middle of the back porch of scanline #224 you can base all future hsync and vsync pulses off of this. At least this is where I had planned on starting.

Is this what you did Mike?

I am also curious as to why you say you only use 17bits per pixel: red0-4, blu0-4, green0-4, shad, and dak. Aren't there shad and dak bits for all three colors?
 

mikejmoffitt

Mickey's Coach
Joined
Feb 6, 2014
Posts
578
I haven't implemented it yet, but yes, my plan was to align the timings to the edges from the blanking signals.

The SHAD and DAK bits appear to be tied together for all the colors in hardware. I don't know if it's separate in the registers or in software, but from what I could tell they are shared. Otherwise, why wouldn't they just be considered additional bits of color depth for each channel?
 

White Devil

Hardened Shock Trooper
Joined
Nov 26, 2012
Posts
448
It blows my mind how people think of and then implement things like this. Wish I chose a career path closer to stuff like this instead of mental health.
I would buy something like this. Absolutely.
 
Top