Boot to Retroarch?

vol.2

Is it possible to boot straight to retroarch?

mitu

Yes, of course - but then again, if you just want RetroArch then why not give Lakka a try ?

vol.2

I'll try to make this as quick as possible. I'll do it with bullet points.

The Raspberry Pi 4 has an issue with horrendous dot crawl using any GPIO connection. The developers have said that it can't be fixed. It has something to do with the signal lines being laid out too close together on the PCB. Gert says this in the thread for the Gert666, so I'm going to believe him.
This is made even worse if you use the retrotink. I think it's because of the higher bandwidth used by the 8-bit connection.
Because of this, many people who still want to get a VGA output from the Pi are switching to an HDMI-VGA adapter
Lakka doesn't output the proper resolution when using an HDMI to VGA adapter. It simply centers the resolution you set in the config.txt in a 1080p framebuffer. Nothing I have yet tried fixes this.
I loaded up retropie and it seems to work okay when I load retroarch. I have some weird instability with the one super resolution I tried, but that might just need some tweaking of the modeline.

So, I came here to find out if I can exclusive retropie straight into retroarch because that's pretty much all I need to use. Also, if I use a super resolution, Emul Sta will be all squashed, and I'd prefer not fool around with getting individual roms to run in different resolutions when all I need is retroarch anyway.

mitu

The Raspberry Pi 4 has an issue with horrendous dot crawl using any GPIO connection. The developers have said that it can't be fixed. It has something to do with the signal lines being laid out too close together on the PCB. Gert says this in the thread for the Gert666, so I'm going to believe him.

Do you have a reference for this ?

This is made even worse if you use the retrotink. I think it's because of the higher bandwidth used by the 8-bit connection.

I know people have retrotink (ultimate) work on the PI4. What 8-bit connection are you referring to ?

Because of this, many people who still want to get a VGA output from the Pi are switching to an HDMI-VGA adapter

That would make matters worse, IMHO, since the VGA/Scart HATs like RetroTink/VGA666/Pi2Scart produce a better result that going through a scaler+converter.

Now, coming back to your question

the auto-start sequence in RetroPie is calling /opt/retropie/configs/all/autostart.sh, you can modify there what programs should work on start.
RetroArch is installed in /opt/retropie/emulators/retroarch/, with its main configuration in /opt/retropie/configs/all/retroarch.cfg, so you can start it with

/opt/retropie/emulators/retroarch/bin/retroarch --config /opt/retropie/configs/all/retroarch.cfg --menu

from the auto-start file.

To be honest, since you're just trying to have RetroArch work, you can simply install Raspbian on your Pi and then install RetroArch from source. You don't need any of the additional RetroPie setup/emulators and front-end.

vol.2

@mitu

It will be necessary to skim the last few pages of the thread, but the gist is in Gerts answer to this question about the increase in dot crawl. (I'm in no way involved in the discussion) He suggests here what has been proposed on other pages and, if you read far back enough, it's stated that some amount of dot crawl has always been in the GPIO, but it wasn't to severe in previous incarnations.

https://www.raspberrypi.org/forums/viewtopic.php?f=91&t=94424&start=175

"If this is a hardware-related problem, why does it happen only on Raspbian Buster and/or RPi 4, and not on Raspbian Stretch / RPi 3?"

"I don't know. Maybe they use a different drive strength for the GPIO or the Pi4 PCB has the tracks thinner and closer together. It can also be that there is more or different frequency noise on the supply. To trace things like this I would connect my spectrum analyzer to the signal and see if that show up anything different between the builds & PCB's."

I'd like to mention out that I have been able to get the dot crawl down to acceptable levels by exploiting the open pixel clock on the pi. If you push the horizontal resolution to 3840 or so, it will condense the crawl so that it looks more like a subtle shift in the screen, but only if you're looking closely. This will work for me, but I still wish I could use the HDMI. It looks beautiful when I use the method via Raspbian (sharper, better colors, less blooming) and it really simplifies my setup. Not to mention that the dpi24 hat makes cooling fans difficult.

vol.2

@mitu said in Boot to Retroarch?:

I know people have retrotink (ultimate) work on the PI4. What 8-bit connection are you referring to ?

8bits per color "888" vs "666"

That would make matters worse, IMHO, since the VGA/Scart HATs like RetroTink/VGA666/Pi2Scart produce a better result that going through a scaler+converter.

There is no way to avoid Digital to Analog conversion. That's what the Pi hat does. It's much higher quality to take a straight digital signal out of the HDMI and convert it with an external box. I'm using an Extron DVI-VGA. It looks amazing compared to any pi hat. Mike chi stopped making the tink ultimate because he recognized this. Here's a reference for you. Mike is involved in this discussion.
https://shmups.system11.org/viewtopic.php?f=6&t=64797

Now, coming back to your question

the auto-start sequence in RetroPie is calling /opt/retropie/configs/all/autostart.sh, you can modify there what programs should work on start.

RetroArch is installed in /opt/retropie/emulators/retroarch/, with its main configuration in /opt/retropie/configs/all/retroarch.cfg, so you can start it with
/opt/retropie/emulators/retroarch/bin/retroarch --config /opt/retropie/configs/all/retroarch.cfg --menu
from the auto-start file.

To be honest, since you're just trying to have RetroArch work, you can simply install Raspbian on your Pi and then install RetroArch from source. You don't need any of the additional RetroPie setup/emulators and front-end.

Thanks, I had trouble getting this to work outside of X11 on the pi4. X11 isn't an option with a CRT. Also, it creates an unacceptable amount of overhead. If you have a reference to a method for compiling retroarch on the pi4 on Raspbian, I would be grateful. The popular thread that people used to use for that is now outdated. :(

mitu

There is no way to avoid Digital to Analog conversion. That's what the Pi hat does. .. Mike chi stopped making the tink ultimate because he recognized this. Here's a reference for you. Mike is involved in this discussion.

I don't see how you deduced that from the topic, which I've read a few times in the past. The HAT's are not converters, but output a native analog signal directly from the GPIO pins.

The reason @mikechi2 stopped producing it is listed in his blog page - https://www.retrotink.com/blog/retrotink-ultimate-where-is-it:

I'll start by stating: I'm the stereotypical old-school analog EE. It means I'm grumpy, lazy and absolutely hate dealing with software. My design philosophy has always been "plug-and-play" and making devices simple enough they can be used without a manual.

One of the current challenges is that the Pi is still extremely complex and error-prone. There are too many obscure settings, even for simple things like pairing a Bluetooth controller, and often changing the wrong one means the whole install is fried. We actually invented a term for that at my company: "Jungling". One of our engineers even threw it up on Urban Dictionary ( https://www.urbandictionary.com/define.php?term=Jungling ).

Second, as of 2019, there are many other better options. The MiSTer, in particular, is an amazing platform. For the cores that are available, the MiSTer blows away anything software based in terms of accuracy and latency. It is very easy to connect a MiSTer to a component input CRT. Currently there's no S-video or composite, so maybe I'll take a look at that in 2020...!

Thanks, I had trouble getting this to work outside of X11 on the pi4. X11 isn't an option with a CRT. Also, it creates an unacceptable amount of overhead. If you have a reference to a method for compiling retroarch on the pi4 on Raspbian, I would be grateful. The popular thread that people used to use for that is now outdated. :(

I don't know what guides you've followed, but the Manual Install is all you need to install RetroPie on a PI4. Note that support for the PI4 is still a work in progress, so some issues might crop up.
EDIT: On the PI, RetroPie doesn't use an X11 environment - that's supoprted only on PC installations.

vol.2

@mitu

You're absolutely right, I'm guessing as to why he stopped making the tink ultimate. I think it's a good guess though. If you think about it, there's evidence that he knows the HDMI adapter works well, he even tries it out himself and declares it a good solution. This is all in a thread with a title that basically is "we don't need hats for the pi because the HDMI-VGA solution works really well."
On top of that, his official reason is the challanges arising from technical changes with the pi.
Now, I'm definitely reading between the lines here, but I think it fits extremely well.
Could it be unrelated, I suppose, but is looks like a duck to me.

The pi is absolutely doing a digital to analog conversion to output over the GPIO. The GPU is producing signalling that is, in the case of a gert666, decoded with a resistor ladder. The tink uses an IC to do the conversion. I'm using a fancier device to take the digital output of the HDMI (as a DVI signal) and convert it into an analog signal. In both cases, the conversion is only done once.

As far as installation goes, I was responding to your suggestion of plain Retroarch on top of Raspbian. That's what I can't get working. Retropie I can get going, but it's difficult to manage super resolutions, it seems like a lot of work to setup the resolution switches.

dankcushions

For the cores that are available, the MiSTer blows away anything software based in terms of accuracy and latency

the false meme that MISTer/FPGA emulation is somehow inherently more accurate/less latency than software could ever be persists :(

Retroarch has a new(ish) CRT Auto Switcher that should make CRT stuff easier and automatic. it does super resolutions and all that. however i'm not aware of anyone attempting it via retropie. it should be the best approach.

vol.2

@dankcushions said in Boot to Retroarch?:

the false meme that MISTer/FPGA emulation is somehow inherently more accurate/less latency than software could ever be persists :(

I looked into Mister after reading that when it went up on his blog, and I have to say that Mister seems overly complicated and expensive. It immediately looks like something that would take huge investment of time and money to even evaluate. And then you are already in for it. The pi is cheap and relatively effective. What's even better is that it can be augmented with higher quality hardware. Need a decent sound card? Buy one and plug it in. Need better graphics? Use a fancy processor. All the Pi has to do is handle the software, and that means having a dedicated community like this one. The solution with the biggest community is always the winner, and the low price point of the pi makes it a natural.

Retroarch has a new(ish) CRT Auto Switcher that should make CRT stuff easier and automatic. it does super resolutions and all that. however i'm not aware of anyone attempting it via retropie. it should be the best approach.

Thanks. I've looked into the switchres settings. I think I'll try it eventually. Looks like it will take time to define the graphics modes. For now, I guess I'll stick with the tink for Lakka, because I can use a super resolution for that and Raspbian thru the Extron for any emulation I can run natively. (like Dosbox)