An older but reliable lossy codec. It is often used with the 32-bit version of MMD to create reasonably small files that are easy to preview.

In MikuMikuDance, a "codec" (short for compressor-decompressor) is a small piece of software that shrinks the raw video data as you export your animation to an AVI file. By default, MMD offers , which produces uncompressed video. While this preserves quality, it results in astronomical file sizes—often reaching tens of gigabytes for just one minute of footage—which can easily crash the software or fill up your hard drive. The Best Codecs for MMD Rendering

It’s fast, free, and prevents the "black screen" render bugs common with other codecs.