Screen tearing is a issue of the Raspberry Buster Lite that the current RetroPie image is using. The upcoming version i think it will get rid from this issue.

Some users solved this issue, in the current version of RetroPie, after they use the experimental kms driver, but this add other issues. If you search in the forum about screen tearing you will find a lot of info. Also i recommend to read the wiki about the used of 4k TV with Rpi4: https://retropie.org.uk/docs/Pi4/

@levitatingGuru Hey, I am wondering how you went about installing the kms driver? I am trying to also resolve the screen tearing but can't figure it our for the life of me. I have adapted the config.txt but I have read I have to install the KMS kernel 5.4 or something like that? is that correct?

The issue seems to be specific to RetroArch, standalone emu like ReDream look both sharper and don't have screen tearing.

In RetroArch.cfg i've already set the following to no avail:

video_refresh_rate = "50.000000" video_vsync = "true"

Ok, the 5.15.? Kernel didn't work well. I had some screen dropouts again.
I then tried 5.10.60, which still had the screen tearing issue in Exult. After that I installed 5.10.64, which eliminates the screen tearing. So one of the commits between those versions fixed that. I will test this kernel further in the coming days and report back.

@Mrakobijes said in trying to use KMS driver yields no composite video output (Raspberry Pi 4):

dtoverlay-vc4-kms-v3d-pi4,composite=1

This looks like a mis-spelling, it should be just:

dtoverlay=vc4-kms-v3d,composite=1

and you should start with stock config.txt, instead of the one you're using, which has too many overclocking options which may conflict.

Note that this configuration is not fully supported by RetroPie yet and for the KMS driver is recommended to use an up-to-date Linux kernel/firmware.

You

@dankcushions Sorry, I missed putting it into my post. It is a Rasperry pi 4. @Addison changing the resolution in the display settings seems to have fixed it. Looks like my pis didn't like the TVs resolution. I am guessing it was 4K. It also cleared up all menu lag and the picture just looks better. You guys are all brilliant. Cheers.

@greenhawk84 said in Screen tearimg:

@dankcushions thank you for the info, your support here has been great over the years. So until kms is fully tested and an official update on Retropie is implemented, I will wait. Do you know if when this update drops, will the users have to go in and make sure all the videosnap .mp4 files are ready for the change ?

i don't use videos so can't answer this point. omxplayer will not work in kms as it relied on the old stack. what that means in terms of video capabilities i don't know.

@beldar I don't notice tearing with SNES, NES, Genesis, Neo Geo, or Playstation. But I do notice it on Mortal Kombat 2 arcade which does run at a funky refresh rate. I also noticed it very badly with lr-flycast. Soul Calibur, MKGold, and NFL Blitz all had really bad tearing.

I'd already gotten it worked out - that wasn't really a request for more assistance.

But I thank you nonetheless- knowing the exact path to each individual Retroarch config file will likely be helpful to me in the future knowing my luck. (and skill level)

But with luck, everything is worked out and my GhettoPi Boy shall be fully online and will serve me until a Pi4 version of Retropie released and I get my hands on one. A little beyond that, actually - the first Pi4 we get will likely go into the arcade cabinet rather than my handheld.