Why this Obscure Audio Codec is a Perfect Fit for the N64
Dominic Szablewski adapted the ULC audio codec to the Nintendo 64, reporting 44.1 kHz stereo playback using about 4% of CPU time. ULC uses an MDCT but a simple nibble-based coefficient encoding instead of entropy decoding.
To fit the transform and overlap buffer in the RSP’s 4 KiB data memory, the implementation uses 16-bit fixed point and smaller blocks. The author describes a human-verified, iterative Codex-assisted port to RSP assembly and the resulting 4 KiB instruction-memory constraint.
An HN commenter added historical context about codec patent licensing and disputed the article’s explanation of Conker’s frame-rate problems.