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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Fri Dec 25, 2020 7:48 pm 



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vol.2 wrote:
Ideally, we would also have the log output from boot.


Do you know of an easy way for us to generate and share this log?


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Fri Dec 25, 2020 7:52 pm 


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fernan1234 wrote:
vol.2 wrote:
Ideally, we would also have the log output from boot.


Do you know of an easy way for us to generate and share this log?


I've done it before. I can look it up and try to figure out where it ends up. You might also have to tell the Pi to spit it out. I'm a little time-constrained over the weekend because of holiday stuff, but I'll figure it out and post by early next week.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sat Dec 26, 2020 4:15 am 


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Raspbian and everything were installed from scratch on a 3B+ around early Summer, so whichever stock firmware was in May-Juneish. I have the newest RetroPie for 3B+ (buster some-shizz some-shizz) and do smol updates quite often, every few “commit”s via Retropie Menu.

I have been sharing this config in various FB groups, CRT Discord etc lately, seems to go fine for anyone who has tried? Seems almost like a mountain is being made outta a mole-hill here, haha. Whenever I need to flash my SD card and get the urge to star anew, I just do the official most recent 3B+ release and use my same ol “retropie-mount” USB stick with all folders but ROMS and BIOS cleared, and any gamelist.xml that may be hiding on the USB.

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^ there’s my buddy’s attempt last night

https://www.instagram.com/p/CIsKv4IFlX8 ... nyzx4cg1hp

https://www.instagram.com/p/CIsJrJelei_ ... 0uwk39aqvc

https://www.instagram.com/p/CInIw2ZlsDO ... otv0mjlwtt

https://www.instagram.com/p/CIWVLtMlBgk ... zkzklweacw

https://www.instagram.com/p/CInHigTlRZj ... 55rgp4umu5

^ Insta posts here are all very recent forays
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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sun Dec 27, 2020 9:29 pm 


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kitty666cats wrote:
Raspbian and everything were installed from scratch on a 3B+ around early Summer, so whichever stock firmware was in May-Juneish. I have the newest RetroPie for 3B+ (buster some-shizz some-shizz) and do smol updates quite often, every few “commit”s via Retropie Menu.


The Pi3 and older do not have a flashed eeprom that holds a traditional firmware. The kernel and firmware on anything pre-4 is a software update basically. It is updated independently of the OS.
In your case, you are using Retropie, so it's current with whatever kernel revision that Retropie is compiling for the specific release that you are using, and was then updated (if and only if Retropie updated their kernel) when you did an update. AFAIK, they "roll-their-own" with that, so it would be a special case.

Here's and explanation from the engineers at the Pi foundation:

"The Linux kernel runs on the ARM, and is loaded from kernel*.img in /boot with support libraries in /lib/modules.
The VideoCore VPU is often referred to as the GPU, and runs what is typically termed the firmware. This is one of the start*.elf files from /boot. It controls the closed source parts of the Pi, such as the codecs, ISP, and original display stack."


So, in addition to the "kernel" changing, there is also a closed-source software stack for the Pi3B+ referred to as the VPU firmware, which is essentially the video bios for the GPU. This file is in the boot sector and is one of the start*.elf files. It's still somewhat unclear to me how often this gets updated, but if that particular file changes, it will have a substantial effect on the behavior of the display stack.



It looks like we have 3 major variables from the pi itself: 1) kernel 2) firmware 3) OS (flavor & revision)

In addition to the Pi, there is also the display itself and the hdmi-[analog RGB] adapter being used.


-I have the chronological list of kernel revisions here (there are over a thousand):
kernel revisions: https://github.com/raspberrypi/firmware/commits/master

-Here's how one would go about figuring out the current "kernel" they are running and the output of the boot log:

type "uname -a" and read the output. you might have to append it with "| more" if you are getting the text moving by too fast to read; that should pause for you when it reaches the end of the screen.

-logfile is called "boot.log" and is located at /var/log/boot.log. That should contain the parsed boot log and show what modedb is doing. if there is some error in the video output.


I am looking into the [GPU] firmware; I'll update when I can.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sat Jan 09, 2021 3:51 pm 



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Seems the RPi-to-CRT rabbit hole only gets deeper. So it's about EDIDs and modelines now? Wow :)

I've only skimmed this thread, but it actually seems that the old method (analogue hat/cable) is not worse at all, if not better. At least it's pretty much rock solid on my 3B+ & Pi2SCART. You can use one of fairly simple runcommand-on-start.shs floating around, or this fancy image: https://github.com/krahsdevil/Retropie-CRT-Edition


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sat Jan 09, 2021 4:20 pm 


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dreadnought wrote:
I've only skimmed this thread, but it actually seems that the old method (analogue hat/cable) is not worse at all, if not better.


I am currently using a retrotink ultimate pi hat, and it looks great for 99.9% of what I want to use it for, but there are still reasons to go with HDMI-VGA adapters.


-no interlaced video over GPIO (biggest issue)

-pi hat takes up GPIO space for directly wired peripherals

-pi hat is cumbersome and requires a custom made, larger case and complicates cooling

-good hdmi-vga converters are cheap and abundant, while high quality (dpi24) VGA pi hats are expensive and quality varies based on the implementation.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sat Jan 09, 2021 5:28 pm 



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For sure, these are valid reasons, especially if somebody needs cooling or the GPIO itself. About the price, I don't know - at least here in Europe the likes of Pi2SCART can be had for ~30 Euros. So unless you have some spare gear or can make your own cable you are probably going to spend same, or more, to get from the adapter to the TV.

But, don't get me wrong, I'm always happy to hear about new methods of displaying being available, especially if it matures to the point of working well on Pi4.

I just get I have a lil' bit of trauma from my time as an early adopter with Pi2SCART back in the day....it was a long struggle before we got it into a reasonable shape ;)


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sat Jan 09, 2021 7:14 pm 


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dreadnought wrote:
Pi2SCART can be had for ~30 Euros


Pi2SCART is a 666 device. Similar devices can be had for less than $5 US with a VGA connector. They are alright, but there is consistency issues when you are fully reliant on a resistor ladder to decode the color values. Each and every one of those devices is going to give you a slightly different result, based on variances in the values. Also, you're not getting full color depth with 666. The 888 devices (dpi24) are generally built with an IC as opposed to a resistor ladder, and are going to give you full 8 bit color on each channel. They used to cost around $100 US, but the RT Ultimate isn't made anymore, and I'm not aware of any others ATM. There used to be a company who made them called Lotech, but they seem to have closed, and I don't know if they were any good to begin with.

Because there are no viable 888 devices being made or supported anymore, future development of retrogaming on the Pi4 over CRT must fall to HDMI-VGA devices; sorting out any issues or hurdles associated with it is what this thread is about.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sat Jan 09, 2021 11:32 pm 


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https://www.instagram.com/p/CJz4V51leRo ... 7eyb18j5oj

^ Waku Waku 7 arcade ver

https://www.instagram.com/p/CJz4jwiF6W2 ... 879j2pjesf

^ Street Fighter Zero 3 arcade

Both are gorgeous looking and running flawlessly with my Portta + sync combiner, lovin’ it! I’m planning on making a pre-configured image pretty soon, as well as a ROMset if my Google Drive has enough room. It’s essentially all the consoles you see on most of the CRT based images, except with X68000 and PC98 on there pre configured (...for 15kHz) as well.

A good PSU is absolutely a must, I am rocking one of these and it’s the best I’ve ever had for Pi
Argon ONE Raspberry Pi Micro USB Cable Power Supply 5.25 Volts 3 Amps | UL Listed https://www.amazon.com/dp/B07MC7B9X3/re ... -FbT0A0D01
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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sun Jan 10, 2021 3:44 pm 



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kitty666cats wrote:
except with X68000 and PC98 on there pre configured (...for 15kHz) as well.


With systems like this the HDMI solution shines in particular, because most games on these systems don't fit within a 240p vertical resolution, and so if you want them on an SD only TV or monitor then 480i 15khz is the way to go. Actually I think virtually all PC98 games have a 400 pixel vertical height, which makes them have a sort of letterboxed look when displayed with a 480i or 480p setting (I guess you could use vertical stretching on the CRT to make them look more like how I assume they look on some of the original NEC monitors).


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sun Jan 10, 2021 8:00 pm 


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fernan1234 wrote:
[
With systems like this the HDMI solution shines in particular, because most games on these systems don't fit within a 240p vertical resolution, and so if you want them on an SD only TV or monitor then 480i 15khz is the way to go. Actually I think virtually all PC98 games have a 400 pixel vertical height, which makes them have a sort of letterboxed look when displayed with a 480i or 480p setting (I guess you could use vertical stretching on the CRT to make them look more like how I assume they look on some of the original NEC monitors).



After lots and lots of deliberation on how to handle Xx200 and Xx400 resolutions, I came up with what works quite well for me. On many PVMs, there is an underscan button on the front; in order to dial in 400 vertical lines for late 80s microcomputers (which is always 200 lines that has been line-doubled AFAIK), I set the underscan to fill up the screen normally, and set the regular scan to 200 lines vertical. This works fine because the games produce a 200 line vertical and the hardware is expected to do the line doubling.

I'm not sure how this would shake-out with an HDMI-VGA adapter, but it works a treat with an analog hat. For example, here's what Quake looks like in 320x400:

Spoiler: show
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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Sun Jan 10, 2021 8:44 pm 



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vol.2 wrote:
I'm not sure how this would shake-out with an HDMI-VGA adapter,


It works fine too. Either way it's just a matter of playing with the picture sizing or overscan/underscan profiles like you suggest. On my BVM I already have other uses for my 4:3 profiles though, so I just live with the letterboxed look for vertical 200 and 400 games. I actually find that in many cases, especially for the PC98 games, the graphics seem to have the correct proportions that way. I also recall seeing some official NEC promotional material where the picture was displayed like that on some of their 4:3 monitors.

Some X68k content can be trickier. Some games do have dipswitch settings for 15khz or 24khz output.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Mon Jan 11, 2021 9:03 am 


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I got a multiformat, so for myself personally I just go into my config and change it to 640x480 DMT instead. In the video below I’m running 31kHz X68K - I think I got the sizing right?

https://www.instagram.com/p/CDCjoozFyNw ... e02zhw13xw

^ weren’t the games somewhat pillarboxed (and the PS1 version of this game is technically stretched out?)

...and then PC98, somewhat letterboxed... yup? Or note quite so?
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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Mon Jan 11, 2021 2:00 pm 



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kitty666cats wrote:
I got a multiformat, so for myself personally I just go into my config and change it to 640x480 DMT instead. In the video below I’m running 31kHz X68K - I think I got the sizing right?

https://www.instagram.com/p/CDCjoozFyNw ... e02zhw13xw

^ weren’t the games somewhat pillarboxed (and the PS1 version of this game is technically stretched out?)


For a multiformat you could also use mode CEA 2 which is the EDTV 480p mode, instead of the DMT 640x480 mode which is a PC resolution mode. The CEA 2 mode should be displayed more wide or less pillarboxed. But I'm not sure which appearance is closer to what you'd see on a real X68K and a contemporaneous monitor, as I've never seen one myself in person. There's probably some pictures and videos out there that can be used for reference.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Tue Jan 12, 2021 4:38 am 


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fernan1234 wrote:
kitty666cats wrote:
I got a multiformat, so for myself personally I just go into my config and change it to 640x480 DMT instead. In the video below I’m running 31kHz X68K - I think I got the sizing right?

https://www.instagram.com/p/CDCjoozFyNw ... e02zhw13xw

^ weren’t the games somewhat pillarboxed (and the PS1 version of this game is technically stretched out?)


For a multiformat you could also use mode CEA 2 which is the EDTV 480p mode, instead of the DMT 640x480 mode which is a PC resolution mode. The CEA 2 mode should be displayed more wide or less pillarboxed. But I'm not sure which appearance is closer to what you'd see on a real X68K and a contemporaneous monitor, as I've never seen one myself in person. There's probably some pictures and videos out there that can be used for reference.


It’s actually got a separate VGA board (my multiformat monitor, utilizing this 15kHz RGB mod http://mikejmoffitt.com/articles/0051-nettv-rgb.html ), hence opting for the DMT mode. I’ll give CEA a try one of these days, have had no issues with DMT 4 tho :) I just kept my Pi at DMT 4 at all times and would simply activate my mini-SLG for games/consoles that are originally 240p, and turn it off for DOSBox and ScummVM. And then run KODI at 720p - here’s how I connected: https://media.discordapp.net/attachment ... image0.jpg
...but now just use a separate 240p image

Also @vol.2 this is the 24bit VGA hat you mentioned, still readily available (have not personally tried one yet) https://texelec.com/product/lo-tech-rpi-vga-board/
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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Tue Jan 12, 2021 5:14 am 


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kitty666cats wrote:

Also @vol.2 this is the 24bit VGA hat you mentioned, still readily available (have not personally tried one yet) https://texelec.com/product/lo-tech-rpi-vga-board/



I mentioned that one as something I had seen on the web, but also that I don't know if it's any good. Looking at the board now I can see it's just a resistor ladder and not an IC to do the color values. The only 24bit VGA hat I've used for a Pi is the Retrotink Ultimate. I would wait until you can score one used (though I haven't seen one on ebay for a long, long time). You might find someone on the forum who doesn't want theirs anymore.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Tue Jan 12, 2021 10:53 pm 


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Mm, not too interested in the RTUltimate myself, plenty happy with what I have. Wonder if someone will make their own run for a price less than 3 friggin digits, heh. I know it was made “open source” but as far as I remember there was either no BOM released / some sort of pretty essential info that was not included...? Anyhoo, dunno how expensive it is for someone to make a run, but I would assume it’s plenty fathomable to make them with a MSRP not exceeding 3 digits :o

Anyone here happen to have a link to a guide for properly compressing a Pi image to share with other folks? Never done so, just wanna make sure there isn’t some step I may be overlooking. I’m gonna put in a teensy bit more work on the RetroArch scaling settings for all the consoles on my Pi and get the pre-configured image up soonish:)
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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Tue Jan 12, 2021 11:10 pm 


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kitty666cats wrote:
Anyone here happen to have a link to a guide for properly compressing a Pi image to share with other folks?


You can just use win32 disk imager to save a copy of the disk image. Then you just compress it; use 7zip or something common. There's no special steps or anything; it's the same as saving a disk image of a floppy or a cd-rom, etc.

Make sure you save the image from an unexpanded filesystem. If you have, say a 32Gb SD card, and your filesystem takes up the whole card, your image is going to be 32Gb big. Easiest way around it is to use the smallest SD card you can get away with from the start.

RE: RTU. i doubt anyone will make more of them for sale. The main issue being that the enthusiast community has lost interest in the Pi and is favoring other things (especially Mister). It's happening for a number of reasons, but mainly that the Pi is a pain in the ass to develop for because the hardware is constantly in hobbiest-level flux and the Pi foundation doesn't give a rats-ass about appeasing the retro-gaming community. Especially awful is the anemic GPU and the poor documentation. The only way that I can see things changing for the Pi is if Jeff Geerling ever manages to get video cards working on the PCI express slot in the compute module. If that happens, it should be possible to just use it as an ARM-based linux machine with a normal GPU using something like Ubuntu.


Last edited by vol.2 on Tue Jan 12, 2021 11:18 pm, edited 1 time in total.

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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Tue Jan 12, 2021 11:18 pm 


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Quote:
You can just use win32 disk imager to save a copy of the disk image. Then you just compress it; use 7zip or something common.

the problem with that is different brands of SD cards slightly vary in size, so for example an image created from a 32GB Sandisk card won't fit onto a 32GB Transcend card.

This is a nice way to start: https://github.com/Drewsif/PiShrink

Create an image, run it through PiShrink and distribute it. The image can be written to any SD card size afterwards (well, needs to by physically larger than the compressed image size of course) and will expand to utilize the full target SD card once first boted up.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 8:42 am 


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Thanks for the input, guys! I will make a pre-configured image, as well as my BIOS folder so nobody has to go through the headache of gathering up the proper np2kai files, heh. I doubt I can fit my 256GB of ROMs, but I will probably put in a 'roms' folder with some games for all consoles (so people can make sure the configurations are all good for their respective CRT) to go with the BIOS folder... and I HIGHLY recommend putting said folders in a separate 'retropie-mount' USB stick :)
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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 2:26 pm 


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really looking forward to it - having a good basis with proper bios files in place and video setup is an excellent start.

Do you currently use

hdmi_group=1
hdmi_mode=8
hdmi_pixel_encoding=4

for 240p output ? This sets Emulationstation to 240p as well, right? Sorry if I missed it in the discussion above, but wouldn't it be better to run the UI in 480i (hdmi_mode=6) and set 240p as a target resolution for Retroarch only ?

Also what shader do you use to minimize horizontal shimmer on 240p output ? The super resolution approach (1440x240p) tries to minimize it by increasing the horizontal res, but if you're running 720x240, how do you react to the games varying horizontal res. E.g. how do you treat a 256px wide game vs. a 352px wide wide game? The usual oversampling shaders tend to work better with higher resolution.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 5:08 pm 


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Fudoh wrote:
This sets Emulationstation to 240p as well, right?


Emulationstation is actually just the little GUI that is used to tie together the Retropie launcher with all of the various emulators. If you want to have greater control over things, I would recommend using Lakka.

The issue with Retropie is that you are going to be dealing with multiple layers of programs, all of which are going to have some bearing on the video output at different moments and might not work out well with the global settings. Generally, the set-it-and-forget-it settings are going to be okay for most people, but if you want to fine-tune things it's better to launch straight into RetroArch (or Lakka) and go from there.

The main problem with Lakka is that it's version is behind regular RetroArch and it also lacks full core support. For that reason, I just use a plain ARM Retroarch install in Raspberry Pi OS. That gives you full support for all armhf cores, but you have to compile RetroArch by yourself and you might have to do so with some of the cores. (N64 is the only one I can think of actually)

Quote:
Sorry if I missed it in the discussion above, but wouldn't it be better to run the UI in 480i (hdmi_mode=6) and set 240p as a target resolution for Retroarch only ?


I've never heard anyone suggest running RetroPie interlaced. I would assume that the text will be more readable in 240p?

Quote:
Also what shader do you use to minimize horizontal shimmer on 240p output ?


Let me outline why the dot crawl happens on the Pi3:

You get dot-crawl with the VGA666 device because the analog video signaling lines are too close on the PCB and the pixel clock cannot go down past a certain point because of being strictly tied to the GPU clock (divisibly).
The clock issue got fixed on the Pi4, but the lines are still too close.

AFAIK, the only way to completely fix the dot crawl on a Pi3 is to output at a high enough pixel clock to satisfy the limitations of the setup (1920x240 should do it) AND to use an HDMI-VGA adapter. However, raising the resolution high enough usually is sufficient for most people. 2560x240 or thereabouts is plenty. Mike Chee's numbers for the RT Ultimate work quite well and can be used as a general guide: https://www.retrotink.com/post/retrotin ... here-is-it

I don't know about using a shader, I've never heard of that approach to killing dot-crawl.

Quote:
but if you're running 720x240, how do you react to the games varying horizontal res. E.g. how do you treat a 256px wide game vs. a 352px wide wide game? The usual oversampling shaders tend to work better with higher resolution.


Typically, the porches will be different on those two resolutions, so they should come out stretched to the screen correctly. The emulation core should take control over the graphics subsystem and output it's original system resolution.
Then RetroArch takes that and spits it out at the resolution you define in the Retroarch video output scaling settings (in Retropie the same thing is done, but Retropie sets RetroArch resolution on a case-by-case situation), governed by the video mode set in your system. For example, if you set your system resolution to 1920x240 with porches that fit your screen, you should end up with something that basically fits, but might take a little fiddling with your TV H size in some cases. You could also tweak your base modeline on Pi in the config.txt in order to have the correct porches for the H resolution you want.

All of this kind of fine-tuning is an order of magnitude more difficult when 1) using Retropie and 2) using an HDMI-VGA adapater. In both cases because you have additional arbitration of the settings; in the case of HDMI-VGA it is because modedb acts as a gate-keeper to accepted output resolution (and must pick from it's own pool). Once you get into the actual software and launch an emulator, I think that it takes over, but modedb is going to thwart your attempts to even launch the GUI if it doesn't like your settings. In the case of Retropie, it's the Retropie software itself that obfuscates the settings.

There are some more advanced automatic resolution switching options, but they require the use of a multiformat monitor. CRT-SwitchRes by alphanu1 is the most advanced of these options, but I'm not sure how development has been over the last year. It basically *works* at this point, but you will be running things at 31kHz rates.

Hope that makes sense, and sorry if I couldn't answer your specific question about shaders. I've only ever used the GBA shaders on a CRT, and that's mostly for the color options.

Let me know if I was confusing and I'll try to be more clear.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 5:36 pm 


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kitty666cats wrote:
I know it was made “open source” but as far as I remember there was either no BOM released / some sort of pretty essential info that was not included...?


it looks like it's all there to me: https://www.retrotink.com/post/retrotin ... pen-source

you would have to program the PIC32. looks like it would cost $30-50 for the programmer.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 6:18 pm 


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Quote:
Emulationstation is actually just the little GUI that is used to tie together the Retropie launcher with all of the various emulators.

I know, but I personally think that Retroarch itself has the worst user interface ever created by any human being. And Lakka is just a light-weight linux (just like Retropie basically), with the difference being that Lakka relies on the genuine Retroarch GUI, while Retropie uses ES instead.

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Generally, the set-it-and-forget-it settings are going to be okay for most people, but if you want to fine-tune things it's better to launch straight into RetroArch (or Lakka) and go from there.

I think Retropie offers the same options. Yes, they're all over the place, but it don't think it's missing functionality.

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For that reason, I just use a plain ARM Retroarch install in Raspberry Pi OS. That gives you full support for all armhf cores, but you have to compile RetroArch by yourself and you might have to do so with some of the cores.

way beyond what I want to use a Pi setup for, but I get the advantages.

Quote:
I've never heard anyone suggest running RetroPie interlaced. I would assume that the text will be more readable in 240p?

definitely. There are certainly ES themes which are suited for 240p, but something like the regular carbon theme just isn't meant for 240p, while it works pretty good in 480i.

Quote:
Let me outline why the dot crawl happens on the Pi3:

are we talking about the same thing ? Dot crawl is usually what happens on composite video along vertical color edges.

What I (and PROBABLY you as well) meant is the horizontal scaling issue you get when using non-integer scaling factors, for example what you're seeing on the HDMI NES or the NES Mini. Yes, I understand that super resolutions are a solid way to fix this, but I was asking because kitty666cats was refering to that specific 720x240p HDMI mode on the previous page.

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All of this kind of fine-tuning is an order of magnitude more difficult when 1) using Retropie and 2) using an HDMI-VGA adapater. In both cases because you have additional arbitration of the settings; in the case of HDMI-VGA

understood, but I'm looking for the easiest solution to adapt an existing setup for a short session on CRT, not to setting up a fresh 240p-dedicated setup.

Quote:
Hope that makes sense, and sorry if I couldn't answer your specific question about shaders. I've only ever used the GBA shaders on a CRT, and that's mostly for the color options.

that's alright. My question way mainly aimed at kitty666cats and his particular setup and image.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 6:52 pm 


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Fudoh wrote:
are we talking about the same thing ? Dot crawl is usually what happens on composite video along vertical color edges.


No.

Quote:
What I (and PROBABLY you as well) meant is the horizontal scaling issue you get when using non-integer scaling factors, for example what you're seeing on the HDMI NES or the NES Mini.


No. That's not what I'm talking about. The Pi3 exhibits significant pixel shimmering and movement at lower resolutions, visually similar to dot crawl. This is caused by the reasons that I mentioned beforehand. I assume that the issue effects all output modes, including HDMI, because I have experience the same issue with a HDMI-VGA converter myself. The Pi4 fixes this issue by virtue of handling the pixel clock differently (not by design, but by coincidence).
AFAIK, you will want to be operating at a super resolution with a Pi 3.

Quote:
understood, but I'm looking for the easiest solution to adapt an existing setup for a short session on CRT, not to setting up a fresh 240p-dedicated setup.


A bog-standard Retropie install using fernan's config setting from the first comment should just work on a Pi3. There was a couple comments a few pages back that claimed it stopped working, but that hasn't been verified. It seems like kittykats has it working fine, maybe just with some tweaks to the modeline which would be specific to his particular monitor (porches, timing).

When I was using an HDMI-VGA dongle, I was able to use CEA mode 12 (1920x240).


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 7:43 pm 


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thanks for clarifying! Now it makes sense. CEA mode 12 also looks good.

How does Retroarch see a CEA mode 12 timing ? Is it recognized as 4:3 (so you get "fullscreen" output with setting RA to 4:3) or 16:3 instead ?


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 9:15 pm 


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Fudoh wrote:
thanks for clarifying! Now it makes sense. CEA mode 12 also looks good.

How does Retroarch see a CEA mode 12 timing ? Is it recognized as 4:3 (so you get "fullscreen" output with setting RA to 4:3) or 16:3 instead ?


I would have to go back and look at my notes to be sure (and those are all comments in code somewhere), but I think yes, it was 4:3. Mode 12 is supposed to be 4:3 IAC. I suppose it's down to what you HDMI-VGA adapter makes of it, because that's going to be the final arbiter of what goes to your screen.

CEA mode 12 is: 240p4x DAR 4∶3 PAR 1:9-10:9 Pixel Clock 54 Vert 60 Hor 15.734 Active: 2880, 240 Total: 3432, 262.5 field rate, 60

Not all adapters will do it I guess. I found at least a couple that had no issue. For sure the extron DVI-RGB is fine.


You've kind of renewed my interest in the puzzle, and I was sort of thinking in the background of trying it again (also I've recently purchased a new adapter I'd like to try), so I will see if an easy, standard install will work and let you know how I get on in parallel. If kittykats gets you up and going first all the better.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 10:34 pm 


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A question about these quadrupled CEA modes. The original idea behind these is to raise the pixel clock above a certain compatibility threshold, right?

Does Retroarch internally see this kind of resolution? I mean, if you go into the video settings and chose a custom AR setting, where you can set the pixel count for both axis manually, what number does RA see here as fullscreen ? Can't try it right now with my Pi connected to a HD screen, which doesn't take any of the 240p resolutions through HDMI.

Regarding Retropie: here you can set the ES resolution globally through the config.txt, while you set the resolution for each emulator videomodes.cfg. This is where run command saves its settings. The run command option screen doesn't give you all the CEA modes for selection through the menu though, but you can easily edit the .cfg file by hand and just change the CEA mode to 8 or 12.

I'll grab one of my HDMI to component boxes over the next days and give this a try on a small BVM.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 10:48 pm 



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In my experience, all of those doubled and quadrupled CEA modes do not make any difference whatsoever, at least on a CRT.

And I'd also say that having EmulationStation or whatever front end for core/game loading is definitely better with 480i than 240p. It's one of the advantages of using the HDMI output instead of a hat. That's one of the things I like about Recalbox, as I mentioned in the original post, which easily allows you to set different CEA modes for the front end as well as each individual system and core (along with the bundled Kodi) by editing the conf text file.


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 Post subject: Re: 240p via HDMI on Raspberry Pi to RGBS, no need for RGB h
PostPosted: Wed Jan 13, 2021 11:03 pm 


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Thanks!

I prefered Recalbox for the longest time as well, but in more recent time I found it to more limiting. After tweaking Retropie a bit and getting rid of all the terminal messages I found it to be a bit more open and with more options at the user's hand. I mean after all, they're very similar. Recalbox tries to keep you away from many of the deeper settings, which can be frustrating in some instances.

Quote:
all of those doubled and quadrupled CEA modes do not make any difference whatsoever, at least on a CRT

which brings me back to my original question. Is it important to make sure Retroarch is using an integer horizontal scale? By default it doesn't (but scales to a given AR instead), which on HD resolutions can be easily resolved using an oversampling filter, but what about 240p?


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