You need to convert them. Software like Karaoke Builder Studio or the free MakeMKV (in conjunction with FFmpeg) can render your MP3+G pairs into MP4 video files. This takes time (hours for a large library), but it's worth it for compatibility.
±50 ms for acceptable user experience; ±10 ms for professional use. karaoke video files
Physical MP4 files remain the gold standard for . As 4K and even 8K backgrounds become common, file sizes will grow (from ~50MB to 200MB per song), but storage is cheap. What won't change is the need for perfectly synced, high-quality karaoke video files. You need to convert them
Unlike simple lyric sheets or audio-only karaoke tracks, video files handle all the timing internally. You press play, and the bouncing ball does the rest. ±50 ms for acceptable user experience; ±10 ms