This codec would have been great 27 years ago! I suspect it wouldn't have gotten past the patent lawyers in 1999 though. It seems cute today but the entire codec space was a patent minefield, the N64 mp3 decoder was implemented twice (once based on the reference codec, once clean) with Nintendo/Rare then paying RAD game tools to license their decoder... of which none of their code was used but they had a license from the mp3 patent holder (Fraunhofer) which then shielded Nintendo from lawsuits. Fraunhofer wanted something like $250k to license directly which wasn't going to fly.
I'll also note the frame rate issues in Conker were mainly down to raw RDP fillrate issues, which was for sure the weakest part of the N64 hardware, it could draw beautiful triangles (for the time) but oh so so slowly. There was a decent amount of speech during gameplay using the RSP mp3 codec. The cartridge size was still an issue, 64Mb got a good amount of mono speech but was still very much at a premium.
In case anyone else got to the demo thinking the quality is awful -- the vocals are incomprehensible and keep cutting out -- it turns out it's like that in the original track:
I wonder if this would also be a great fit for the MAS3507D! Supposedly you can replace the program with your own in a 1-kiloword RAM (the default MP3 decoder is in ROM, and probably larger). If you can fit this codec in 1024 MIPS instructions, perhaps you can do the same in 1024 of these DSP instructions…
Too bad there is seemingly zero public documentation on the format of these programs, though (and no emulator or similar).
Pardon my ignorance but one thing I'm curious about, if the decoder fills almost the entire 4k RSP instruction memory (IMEM) - wouldn't that be something games need for graphics? If so, then is this still usable for say a game?
Didn't Top Gear Overdrive (1998) use MP3 tracks? It had several tracks by Grindstone that would play during races. The audio quality isn't that great but lyrics are mostly comprehendible.
Wipeout 64 had some music by Fluke and Propellerheads but I'm pretty sure it used some tracker format to re-create the tracks from short recordings and honestly, they sound awful, not just because the audio quality but because the repetitiveness and lack of progression.
Obscure audio codec is a perfect fit for the N64
(phoboslab.org)256 points by frostbyte7 5 November 2026 | 30 comments
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I'll also note the frame rate issues in Conker were mainly down to raw RDP fillrate issues, which was for sure the weakest part of the N64 hardware, it could draw beautiful triangles (for the time) but oh so so slowly. There was a decent amount of speech during gameplay using the RSP mp3 codec. The cartridge size was still an issue, 64Mb got a good amount of mono speech but was still very much at a premium.
https://www.youtube.com/watch?v=i1gVxKhdGPs&t=57s
Too bad there is seemingly zero public documentation on the format of these programs, though (and no emulator or similar).
The demoscene and homebrew scene is dying as we speak.
Pardon my ignorance but one thing I'm curious about, if the decoder fills almost the entire 4k RSP instruction memory (IMEM) - wouldn't that be something games need for graphics? If so, then is this still usable for say a game?
https://www.youtube.com/watch?v=kyXsWd7DpEs
Wipeout 64 had some music by Fluke and Propellerheads but I'm pretty sure it used some tracker format to re-create the tracks from short recordings and honestly, they sound awful, not just because the audio quality but because the repetitiveness and lack of progression.