Cinepak is a video codec developed by Peter Barrett at SuperMac Technologies, and released in 1991 with the Video Spigot, and then in 1992 as part of Apple Computer's QuickTime video suite. It was designed to encode 320x240 resolution video at 1x (150 kbyte/s) CD-ROM transfer rates. The codec was ported to the Microsoft Windows platform in 1993. It was also used on first-generation and some second-generation CD-ROM game consoles, such as the Atari Jaguar CD, Sega CD, Sega Saturn, and 3DO.

It was the primary video codec of early versions of QuickTime and Microsoft Video for Windows, but was later superseded by Sorenson Video, Intel Indeo, and most recently MPEG-4 and H.264. However, movies compressed with Cinepak are generally still playable in most media players.

Cinepak is based on vector quantization, which is a significantly different algorithm from the discrete cosine transform (DCT) algorithm used by most current codecs (in particular the MPEG family, as well as JPEG). This permitted implementation on relatively slow CPUs (video encoded in Cinepak will usually play fine even on a 25 MHz Motorola 68030, consoles like the Sega CD usually used even slower CPUs, e.g. a 2.5MHz 68000), but tended to result in blocky artifacting at low bitrates, which explained the criticism levelled at the FMV-based video games.