Change resolution in emulator to 640x480 and work with hardware scankine generator

bodtx

Hi I'm using a scanline generator board pluged between my raspberry and my TFT 19' screen in vga.
the scanline genrator support at max 640x480
In emulstation the res is 1280x1024 (native res), so no scanline in emulstation => not a problem
but when I launch mame lr-2003 for ex the game is using the native resolution, so no scanlines also.
I'd like to change the screen resolution. I've seen some config file but it seems that it does not change the native resolution.

How could I change the resolution to 640x480 for the emulators?

my config
raspberry 3
hdmi to vga
1280x1024 screen
3A plug

mitu

Use the Runcommand launch menu to select the video mode before starting the game. Or just use a Shader on the native resolution to add scanlines without using any hardware.

bodtx

Does it change a propertie in retroarch.cfg? do you know which one?

mitu

@bodtx No, it's not changing the game resolution in RetroArch, it changes the display resolution directly.

thelostsoul

I use HDMI to VGA at 640x480 too. Every emulator or even game can have its own resolution. I enabled the RunCommand launch menu and selected for each system (DMT-4 and 5 means 640x480). I don't know if I forgot something, but here it is.

RunCommand launch menu:
Select default video mode for "SYSTEMNAME" (DMT-4)
and
Select RetroArch render res for "SYSTEMNAME" (5)

Then you can disable the RunCommand. I also set the resolution of EmulationStation itself through the file

/boot/config.txt:
hdmi_group=2
hdmi_mode=4
config_hdmi_boost=5