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Software Support => GroovyMAME => Topic started by: jimmyj1979 on January 11, 2019, 04:40:09 am

Title: Image sharpness with J-Pac vs Pi2Jamma [Log attached]
Post by: jimmyj1979 on January 11, 2019, 04:40:09 am
Ok I thought I was going a bit crazy regarding image sharpness so I decided to do some A/B tests with my Pi2Jamma (Raspberry Pi Jamma Interface) which runs super resolutions 2560x240 and test it against my Groovyarcade Rig (ATI 4550 & vga cable to JPAC)

The results are quite obvious.

The Pi2Jamma looks sharp, you can almost count individual pixels.
(https://i.imgur.com/ixzB6OT.jpg)


With the Jpac the image looks soft, almost like it has anti-aliasing on.
(https://i.imgur.com/eWtcbxD.jpg)

and this should prove my GA machine is in 384x240
(https://i.imgur.com/1vDzdR7.jpg)

Have i done something wrong?
https://imgur.com/gallery/87j9lTB


As you can see in the final pic of that album i took a mame screen grab

Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: jimmyj1979 on January 11, 2019, 04:53:21 am
my guess is that the loss of sharpness is signal degrading over the analogue VGA cable, the pi2jamma plugs directly to the Jamma harness. which could be why its sharper and not as lossy.

I may try a ferrite ring around the VGA cable to try and passively filter noise on that signal. Will report back
Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: Calamity on January 11, 2019, 05:12:45 am
Get a log just in case, and make sure you have no software filter in mame.ini.
Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: jimmyj1979 on January 11, 2019, 08:04:24 am
Gl_glsl_filter is enabled, should I disable this?
Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: Arroyo on January 11, 2019, 08:58:34 am
Gl_glsl_filter is enabled, should I disable this?

Definitely, those filters are generally used to simulate a CRT on another display by introducing scanlines, phosphor glow, screen curvature, etc. to make a non-CRT display look more like a CRT.  Those filters will introduce blurriness and other undesirables.
Title: Does this look right? Apparently 384x224
Post by: jimmyj1979 on January 15, 2019, 11:53:41 pm
(https://i.imgur.com/1vDzdR7g.jpg)

I'm still trying to track down what is causing the blurry output to my CRT.

I have a feeling the vid card thinks its outputting 384x224 but it isnt, i can see some horizontal aliasing or distortion on some of those lines....

are there any ways to test what is going on?

Also... What does dotclockmin actually do? Both my cards apparently support low or 0 dot clocks... but I havent experimented
Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: Calamity on January 16, 2019, 04:15:37 am
I'm still waiting for your log.
Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: jimmyj1979 on January 16, 2019, 05:07:41 pm
Will generate a log tonight, as i am running GroovyArcade, is there any tricks i need to know to create a log under linux?
Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: jimmyj1979 on January 19, 2019, 06:08:26 pm
I'm still waiting for your log.

Hi Calamity, I had some troubles generating a log from the terminal, turns out i had to do it via KDE desktop, Log attached

Title: Re: Image sharpness with J-Pac vs Pi2Jamma [Log attached]
Post by: jimmyj1979 on January 20, 2019, 07:15:35 pm
also found this thread, this sounds like someone had an issue with a Jpac thinking it was software introducing noise but ended up being jpac/vga

http://forum.arcadecontrols.com/index.php/topic,158700.0.html (http://forum.arcadecontrols.com/index.php/topic,158700.0.html)

Title: Re: Image sharpness with J-Pac vs Pi2Jamma [Log attached]
Post by: jimmyj1979 on January 21, 2019, 02:07:42 am
Ive also noticed noise around some text (once again this doesnt happen on my Pi2Jamma


It's quite severe in the image below around the word credit. There is definitely some blue/purple ghosting going on. I would usually agree and say that its an issue with the CRT but it doesnt happen on the Pi2Jamma :|
(https://i.imgur.com/H2ZGhddg.jpg)

(https://i.imgur.com/c1We8Ptg.jpg)
Title: Re: Image sharpness with J-Pac vs Pi2Jamma
Post by: Calamity on January 21, 2019, 05:33:22 am
I'm still waiting for your log.

Hi Calamity, I had some troubles generating a log from the terminal, turns out i had to do it via KDE desktop, Log attached

Hi jimmyj1979,

The log looks perfect, I don't think it's a software issue cause by GLSL filters or incorrect scaling. The video mode is correctly set. The fact that you see artifacts on text rendering in MAME menus is normal, that part of MAME is not designed to work on low resolutions any more. However, regarding the game itself should look crisp.

If you want my opinion, the pictures you posted don't look too bad. I'd say most users would find them good enough. It's only that you have something else to compare. As you say, it looks like the analog chain is causing some signal quality loss.
Title: Re: Image sharpness with J-Pac vs Pi2Jamma [Log attached]
Post by: cools on January 21, 2019, 06:11:19 am
How does it look with super resolutions in GroovyArcade ?
Title: Re: Image sharpness with J-Pac vs Pi2Jamma [Log attached]
Post by: jimmyj1979 on January 21, 2019, 06:28:49 am
Iím not sure how to enable super resolutions in groovy arcade? Any ideas on how I could try?