Fixing Overscan and Cropped Edges Without Distorting the Original Image
How to distinguish intentional console overscan from frontend cropping, display zoom, wrong aspect ratio, and per-core viewport settings.
Old software often placed unstable or decorative pixels near edges that consumer CRTs hid. Emulators may crop that nominal overscan, while a television’s own zoom mode can crop again.
First return the host display to “Just Scan,” “Screen Fit,” or an equivalent 1:1 mode. Disable frontend integer scaling, custom viewport, bezel, and shader cropping temporarily. Then inspect the core’s crop/overscan option by platform; do not compensate with an arbitrary stretched aspect ratio.
Compare against hardware documentation or trusted captures. Some games intentionally draw outside the normally visible area, and different regional standards expose different line counts. Keep a per-core default and a per-game override only when evidence justifies it. Record the original value before changing it so visual troubleshooting remains reversible.
Sources: RetroArch configuration reference, MAME video options