3 way screen split

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imfuraisoth
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3 way screen split

Post by imfuraisoth » Fri Aug 02, 2019 9:23 pm

I'm running on pi4 with latest lakka build and I connected it to my blast city via arpicade just to see if it will work. I got a weird 3 way screen split going on. Not sure what's happening. Is it a setting that I can tweak and fix? It looks like this.
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dee2eR
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Re: 3 way screen split

Post by dee2eR » Sat Aug 03, 2019 12:04 am

Answered in the other thread too...

Are you sending a low res monitor a high res signal?

imfuraisoth
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Re: 3 way screen split

Post by imfuraisoth » Sat Aug 03, 2019 1:49 am

Yeah it’s not an HD monitor. It’s just the standard one that comes with blast city I think. I’m hooking up the pi4 to the arpicade via hdmi port. Though the 4 needs an adapter because it’s a micro hdmi. I thought the arpicade would output the video through jamma in standard def. I’ll try to see if there’s a way to tweak the video settings in lakka. I only saw aspect ratio options.

dee2eR
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Re: 3 way screen split

Post by dee2eR » Sat Aug 03, 2019 2:45 am

You'll need to run the Pi in one of it's low res modes. There's no scaling or anything in the RaspberryJAMMA, that would be unnecessary and add lag and probably artifacting.

On Pi4 as far as I know the accelerated video mode will not stay in low res, there's currently a bug in the driver as far as I understand it... Non hardware accelerated low res works.

Unfortunately I've never tried Lakka to suggest anything.

imfuraisoth
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Re: 3 way screen split

Post by imfuraisoth » Sat Aug 03, 2019 5:36 am

I’ll try to play with the retro arch config to force it to low res. Thanks for the tips!

imfuraisoth
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Re: 3 way screen split

Post by imfuraisoth » Mon Aug 05, 2019 4:24 am

Okay, I'm not sure how to disable HW acceleration. I've tried a bunch of lower resolution settings from this https://www.raspberrypi.org/documentati ... t/video.md

Nothing seemed to help.

sdtv_mode=1
sdtv_aspect=1
hdmi_drive=1
hdmi_group=1 (values I tried: 1,2)
hdmi_mode=8 (values I tried with hdmi_group=1: 2,6,7,8,16,34,56,58 values I tried with hdmi_group=2: 4)
hdmi_force_mode=1

I tried other flags as well but either it didn't work at all and I got no image or it was the same 3 way split image.

What is the resolution and raspberry pi config.txt settings that the 3B+ was set to for the arpicade?

dee2eR
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Re: 3 way screen split

Post by dee2eR » Mon Aug 05, 2019 6:04 am

You'll want group 1 mode 6 or mode 8 for low res, although there are a few more ways to get low res they're the common ones.

Pi3B+ (all earlier Pis too) and Pi4 have different video chips, what works for older Pis doesn't necessarily work on Pi 4. To disable Pi4 video acceleration look for this section in config.txt:
[pi4]
# Enable DRM VC4 V3D driver on top of the dispmanx display stack
#dtoverlay=vc4-fkms-v3d
max_framebuffers=1
The important line is: #dtoverlay=vc4-fkms-v3d if it's not hashed out in your build do so. Once the video driver is working properly hopefully it will be able to use acceleration and low res at the same time.

imfuraisoth
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Re: 3 way screen split

Post by imfuraisoth » Mon Aug 05, 2019 6:48 am

Just tried dtoverlay=vc4-fkms-v3d and still no dice. Same effect.
group = 1, mode = 8
The distroconfig.txt already actually had that set. Maybe I'll just wait for them to release their driver fix. When I'm not connected to the cab and connect to my regular 1080 computer monitor, it will always be in HD no matter what settings I put it in I think.

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