This Obscure Codec Puts 44 kHz Stereo on the N64 for Just 4% of Its CPU
Why This Obscure Audio Codec Is a Perfect Fit for the N64
The N64's cartridge space and 93 MHz CPU made recorded audio nearly impossible, forcing most games into tracker-style sample playback. ULC, a transform codec built for a 16 MHz Game Boy Advance, turns out to be the perfect middle ground: near-Opus quality and bitrate at only four times the complexity of ADPCM. Ported to the RSP in about 1,400 lines of MIPS assembly, it decodes 44.1 kHz stereo using roughly 4% of CPU time and 5% of RSP time, and now ships in Libdragon.
In short: ULC is what MP3 could have been. The same core idea, but without the cruft around it.