Best way to output SCART (RGB) from Pi 3?

Dochartaigh

@tjohnson said in Best way to output SCART (RGB) from Pi 3?:

HDMI_CVT

What's the difference between HDMI_CVT and hdmi_timings (I've been using hdmi_timings as that's what everybody - including the manufacturer - says to use).

maxriptide

@Dochartaigh in my experience hdmi_cvt doesn't work with GPIO output. It works flawlessly with an HDMI-VGA adapter and it is really easy to change resolution parameters, but unfortunately the HDMI-VGA introduces lag, that's why I switched to the Gert GPIO VGA adapter having to deal with hdmi_timings.

tjohnson

@maxriptide Im using vga to hdmi so using hdmi_cvt and have got the resolution and image size working great, not sure on the introduction of lag, some people claim to be sensitive to it, I haven't noticed any lag myself, long term gamer but no "pro" gamer. Has anyone got any hard facts on times to convert the hdmi signal to vga or any tests I could run to determine actual lag?

maxriptide

@tjohnson I am a shmupper and very sensitive to lag. I have tried measuring the lag by the manual lag measurement tool found in the 240p Suite available for Megadrive, PC engine, SNES and some other consoles. At first I got the hang of it with the real consoles (Megadrive and PC engine) where I could measure an average lag of 0,7 frames which roughly should be your "human response time" since it depends on your reflexes, I used this value as a baseline for the upcoming measurement with retropie emulators. With two different HDMI-VGA adapters I got approximately 1 frame lag more than Gert VGA Adapter. Try yourself, it could be interesting to get lag data with different adapters.

tjohnson

@maxriptide had to look up what shmupper meant. I enjoy games like Rtype, Phoenix, Galaga, I'll try and do some lag test with the 240p suite using hdmi to vga and direct output from the composite output.

maxriptide

@tjohnson said in Best way to output SCART (RGB) from Pi 3?:

had to look up what shmupper meant

Sorry for that :-)
@all: it just means I mainly play shoot'em'ups (often abbreviated in shmups)

edmaul69

@tjohnson can you explain what settings i need to do if say i wanted 320x240 using an hdmi to vga adapter? Im not familiar with hdmi_cvt.

maxriptide

@edmaul69
here's the settings I use:
hdmi_group=2
hdmi_mode=87
hdmi_cvt=320 240 60 1 0 0 0

edmaul69

@maxriptide thank you. Out if curiousity what monitor are you using?

tjohnson

@edmaul69 I have these currently set using an hdmi to vga, then using vga to scart adaptor

hdmi_cvt=320 240 60 1 0 0 0
hdmi_group=2
hdmi_mode=87
config_hdmi_boost=4
overscan_scale=1
overscan_left=12
overscan_right=16
overscan_top=15
overscan_bottom=0

I'm using these with an old JVC 21" CRT TV, works very well.

maxriptide

@edmaul69 said in Best way to output SCART (RGB) from Pi 3?:

what monitor are you using?

I'm using both a Sony PVM 1454QM and a Commodore 1084S

aTg

You know RGB-Pi? This is the web of the project rgb-pi.com is ready to work with RetroPie

Dochartaigh

So I FINALLY had a chance to mess with this some more and it's a total mess this time around... See this photo showing PiSCART on the left, and a regular SNES console (hooked up to a PVM via RGB cables). Notice the blue and white lines on the Pi2SCART being all wavy (along with the rest of the photo as well - and not being as clear - and the colors not popping quite as nicely).

I was told on the Arcade Forge Facebook page that I had to go into the RetroArch menu and disable all video filters and set the aspect ratio, res and integer scaling (because RetroPie's default settings are made for HDMI TV's and wreck the image on a CRT). On the several topics about this here, unless I missed it, I haven't seen any reference to this causing problems....but I don't see how in the world it wouldn't as these settings are on by default in RetroPie...

Nobody has replied past that above info on Facebook so I thought I'd get your guys input. From this good post on Lakka Optimal Video Settings, I saw these things to tweak, but don't know if I'm on the right track or not:

Pixel Perfect mode (says best picture quality but "Image is square for some systems (i.e NES and SNES), which results in little black bars to the left and right of the image on a 4:3 TV Screen").

Aspect ratio Index 1:1 (PAR 4:3)
Windowed scale 1.0
Integer scale ON
HW Bilinear Filtering OFF
Threaded Video ON
Vsync ON

Or this mode is for "Full Screen Mode" (little more blurry but should fit to screen for every system).

Aspect ratio Index Core Provided
Windowed scale 3.0
Integer scale OFF
HW Bilinear Filtering ON
Threaded Video ON
Vsync OFF

What would you all suggest? Is this the right track? The most common problem is while I'm flipping through all these options it keeps on changing the Custom viewport size? (or something like that...I really should have taken photos...) - but I know it jumps from like 240p (or native 244p? NES/SNES size) I have the /boot/config.txt set as, to something WAY larger, and doesn't seem to shrink back to that smaller size even if I change the ""Aspect Ratio Index" to "Config" (which should change that back to the config.txt's 256x244 or whatnot).

maxriptide

@Dochartaigh it looks like scaling artifacts, do you have overscan enabled in config.txt?

Dochartaigh

@maxriptide said in Best way to output SCART (RGB) from Pi 3?:

@Dochartaigh it looks like scaling artifacts, do you have overscan enabled in config.txt?

I did have overscan settings on to shrink the image - but something else was also messed up so I started with a fresh /boot/config.txt). I just tried the "Pixel Perfect" settings, versus the "Full Screen" and the Pixel Perfect is definitely more clear.

My problem, in part, is definitely the overscan. With it turned on (which I was using to shrink the image since it was way too large) the image gets all blurry. Is there any other way to shrink the image besides tweaking the overscan settings in /boot/config.txt? (or besides changing the settings on the monitors themselves - which are set perfect for the actual consoles hooked up to them)

edmaul69

@Dochartaigh the correct way to shrink and expand is to use the overscan up, down, left, and right. Adjust those until you get the right size and position. You can use positive and negative numbers (ie: 5, -5) to get it shrunk to the size you need.

maxriptide

@edmaul69 using overscan with such small resolution (320x240) always lead to scaling artifacts which are what Dochartaigh is experiencing

maxriptide

@Dochartaigh said in Best way to output SCART (RGB) from Pi 3?:
Is there any other way to shrink the image besides tweaking the overscan settings in /boot/config.txt?

@Dochartaigh you can try the settings I suggested to you in this thread and try to center the image following the method suggested by Molhoy in this thread: https://retropie.org.uk/forum/topic/8673/how-to-center-image-of-retroarch-with-pi-outputing-240p-rgb-via-hat-board-gert-666-to-pvm/14

Dochartaigh

Hi Gents, so if I'm hearing you both correctly (please let me know if I'm not!), there is NO other way to SHRINK the image via software settings BESIDES overscan, right?

Overscan, like Max said, totally ruins the image quality, so I'm hoping there's something else to try. Centering is perfect (thanks to that post - even tested it with the 240p Test Suite on NES, SNES, and Genesis!).

mikechi2

You guys might want to check out this:

https://discord.gg/gCvP6

Kevin has been doing some great work getting the scaling settings right using a high horizontal resolution (1600 x 240) which eliminates non-integer scaling artifacts.

He using my component video output to a TV but the same theory should apply if you're using SCART on a PVM.