How Did Resident Evil 2 Fit on a Nintendo 64 Cartridge?

Resident Evil 2 has often been hailed as the best game in the franchise, and with nearly six million copies sold on PlayStation alone, it's hard to argue. The game received several ports, but one of the most interesting and technically challenging was for the Nintendo 64. The maximum capacity of a Game Pak is 64 megabytes, yet the final version not only included all the "Full Motion Video", but also suffered no cuts in audio or music.

There's no doubt that Resident Evil 2 is one of those rare cases where a sequel surpasses the original. The story of Leon S. Kennedy and Claire Redfield is gripping from start to finish, and from a certain perspective, we could say it's like two games in one. Zombies, relentless bosses, a femme fatale, a secret ending... it has almost everything. Fans received its remake with open arms (similar to what happened with the remake of Resident Evil 3), and it's likely we'll see Leon and Claire again, with updated graphics.

The Challenge

The game received a total of five ports, but the most surprising of them all is the one that Angel Studios (now Rockstar San Diego), Capcom's Studio 3, and Factor 5 created for the Nintendo 64. Why? Because Resident Evil 2 spans two CDs (thanks to Full Motion Video and an excellent soundtrack), when the Game Pak can only hold a maximum of 64 megabytes at best. So... how did they adapt such a game to the limited capacity of the cartridge?

No Compromises

Released almost two years after the original, Resident Evil 2 for Nintendo 64 made no compromises. Leon, Claire, the environments, the endings, the FMV, and the music are all there. 1.2 gigabytes of data, supercompressed into the Game Pak. Modern Vintage Gamer explains that the final compression rate for the videos was 165 to 1, and only by comparing them side by side with the PlayStation version can we notice the quality differences. As if that weren't enough, all decoding on the Nintendo 64 had to be done via software. Pokémon Puzzle League has about 30 seconds of FMV. In Resident Evil 2, it's 15 minutes.

A precise and careful use of compression and chroma subsampling (chroma subsampling) enabled a reduction in resolution and required bandwidth. At those levels, compression artifacts are inevitable, though they were naturally masked during FMV playback on a CRT television. However, the whole combo proved insufficient. Lowering the video bitrate was ruled out immediately, but that's when the Nintendo 64's custom hardware comes to the rescue.

The Hardware to the Rescue

The console supports vectors, and its Reality Signal Processor (RSP) can execute code in parallel. That allowed them to significantly reduce the resolution of the videos and modify their scale on the fly, with minimal impact on performance. The color space conversion was also redesigned to take advantage of the RSP, but the decompression speed was still too slow. The solution? Compression with frame skipping and interpolation (leaving the final framerate at 15 FPS), and the RSP injecting frames at key moments, creating a sort of "false triple buffering".

The rest of the work focused on reducing texture resolution and using multiple resolutions. Depending on the scene, the game changes its resolution without the player noticing, and the backgrounds are just simple textures, with their scale always modified to the same level (which is why some backgrounds look blurrier than others). What about the audio? The dialogues received heavy compression, while the soundtrack was transformed with the MusyX module, known for its extreme efficiency on the Nintendo 64.

A Masterpiece

In summary, the port of Resident Evil 2 for Nintendo 64 is a masterpiece, made possible thanks to the combined effort of several companies, including Nintendo itself, which gave the green light for low-level access to its hardware. If you still have that console or enjoy emulating it, I think it's not a bad idea to return to Raccoon City...