Video modes and filters¶
The HDMI and the VGA output of the core are simultaneously active, so you can even use both at the same time.
Picture geometry¶
The Game Boy's 160x144 LCD picture is shown centered with a black border in a 256x224 active area - the classic Super Game Boy geometry - at the authentic refresh rate of 59.7275 Hz.
HDMI modes¶
The Game Boy runs at 59.7275 Hz, so all HDMI modes are members of the 60 Hz family. Choose your mode in the "HDMI" submenu of the on-screen-menu:
- 16:9 720p 60 Hz (default)
- 640x480 60 Hz (4:3)
- 720x480 59.94 Hz (4:3)
- 800x600 60 Hz (4:3)
HDMI: Flicker-free¶
"HDMI: Flicker-free" is switched on by default. It gently dithers the core between a 59.73 Hz and a 60.05 Hz leg so that the average is exactly the HDMI rate. This removes the slowly wandering tear line that otherwise appears when a 59.7275 Hz core meets a 60 Hz display. One exception: the 800x600 mode runs at 60.32 Hz, which is above what the faster leg can reach, so a slow tear line can remain in this mode.
Important: Switch "HDMI: Flicker-free" off when you use a VGA display or an analog retro monitor. The dithering makes the sync frequency of the analog output step slightly, which analog displays dislike.
HDMI Aspect Ratio¶
The Aspect Ratio group offers three borderless Handheld LCD sizes plus the complete television-style canvas:
- Handheld LCD Small (10:9) (default) is approximately as tall as the game content in TV-style mode. At 720p it occupies a centered 514x463 rectangle.
- Handheld LCD Medium (10:9) occupies 640x576 at 720p, so every Game Boy pixel becomes an exact 4x4 block.
- Handheld LCD Full (10:9) occupies 800x720 at 720p, so every Game Boy pixel becomes an exact 5x5 block and fills the display height.
- TV-style (4:3) retains the complete Super-Game-Boy-style 256x224 canvas and presents it as it would appear on a traditional television.
All three Handheld choices crop the black border and preserve the physical 10:9 aspect ratio of the original LCD. Their centered output sizes are:
| HDMI mode | Small | Medium | Full |
|---|---|---|---|
| 1280x720 | 514x463 | 640x576 | 800x720 |
| 640x480 | 343x309 | 426x384 | 533x480 |
| 720x480 (physical 4:3) | 386x309 | 480x384 | 600x480 |
| 800x600 | 429x386 | 534x480 | 667x600 |
This setting changes only the HDMI output; all three analog VGA modes keep their existing picture geometry.
HDMI filters¶
The "HDMI Filter" submenu offers eight options:
- No Filter: nearest neighbor
- Sharp Bilinear
- Bicubic
- Smooth
- Lanczos (default)
- Scanlines
- CRT (S-Video)
- CRT (Composite)
The last five options (from "Smooth" on) are polyphase filters. The two CRT options simulate the horizontal smear of S-Video and Composite cabling combined with scanlines.
VGA modes¶
The "VGA" submenu offers three modes:
- Standard (default): 31 kHz scandoubled output with PC-VGA sync pulses. The Game Boy pixels, picture geometry and authentic frame timing are unchanged.
- 15 kHz with HS/VS: for retro CRT monitors.
- 15 kHz with CSYNC: for retro CRT monitors; use CSYNC for RGB/SCART cables.
Important: Whenever a display is connected to the VGA output, switch off "HDMI: Flicker-free" (see above).
OSM Scaling¶
On the analog outputs the on-screen-menu covers almost the whole picture - especially in the 15 kHz modes. The "OSM" submenu scales the menu in nine steps from 100% down to 50% while the picture stays untouched. The menu is rendered from a native 8x8 font, so it stays sharp at every step: 100% shows the classic look and 50% is a pixel-perfect quarter-size menu. The setting applies to the HDMI menu as well.