Howto : change output resolution to 720p on libretro/RetroArch emulators

bilu

/boot/config.txt
Reference: www.raspberrypi.org/documentation/configuration/config-txt/video.md
hdmi_group=1
hdmi_mode=4
hdmi_drive=2

/opt/retropie/configs/all/retroarch.cfg
video_fullscreen = "true"
video_fullscreen_x = "1280"
video_fullscreen_y = "720"

If your setup has overlays you'll need to choose either to:

Disable overlays : Select-X > On-Screen Overlay (under Quick Menu) > Display Overlay (which is the easiest solution but a pity not to use all those great bezels...)

Resize every platform to the new bezel scaling : Select-X > Back (leaving Quick Menu) > Right once > Video (under Drivers) > Scaling > Aspect Ratio : Custom
and then adapt X Position, Y Position, Width and Height until it fits your needs, e.g. for N64 I have 155,-2,970,720 for these parameters.

Before doing this you might want to try a CRT curvature and scanlines shader, my favorite is zfast-crt-curve (and zfast_crt_standard for handhelds).

Selecting shaders: Select-X > Shaders (under Quick Menu) > set Video Shaders to On > Load Shader Preset
Then Save > Save Content Directory Preset

Another option that looks good and although recommended to be disabled with shaders actually fits well with this one is bilinear filtering, already active on most systems:
Select-X > Back (leaving Quick Menu) > Right once > Video (under Drivers) > set Bilinear Filtering to on

For all changes done through the Retroarch menu using Select-X you need to save them using overrides:
Select-X > Overrides > Save Content Directory Overrides (or Game Overrides if specific changes to one game)

If you're using bezels always save content directory overrides from a game that doesn't have a game-specific bezel, else all games of the same system get that bezel.

Same applies to avoiding core overrides, as some emulators cover multiple systems and then you get one system bezel displayed on another e.g. Master System on Mega Drive/Genesis.

bilu

My other relevant threads
https://retropie.org.uk/forum/topic/27429/howto-emulator-performance-tweaks-for-psp-and-n64-and-quality-for-psx
https://retropie.org.uk/forum/topic/27431/howto-major-performance-boost-on-retroarch-based-emulators
https://retropie.org.uk/forum/topic/27430/howto-optimized-boot-config-txt

bilu

Note: if you implement my GPU Hard Sync tweaks from https://retropie.org.uk/forum/topic/27431/howto-major-performance-boost-on-retroarch-based-emulators you'll need to keep both shaders and bilinear filtering disabled.