Cinepak is a lossy 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. One of the first video compression tools to achieve full motion video on CD-ROM, which is why its FourCC identifier is CVID. The codec was ported to Microsoft Windows in 1993. It was also used on fourth- and fifth-generation game consoles, such as the Atari Jaguar CD, Sega CD, Sega Saturn, and 3DO. libavcodec includes a Cinepak decoder and an encoder, both licensed under the terms of the LGPL.
History
It was the primary video codec of early versions of QuickTime and Microsoft Video for Windows, but was later superseded by Sorenson Video, Intel Indeo, and most recently MPEG-4 Part 2 and H.264/MPEG-4 AVC. However, movies compressed with Cinepak are generally still playable in most media players.
Technology
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 12.5 MHz 68000), but tended to result in blocky artifacting at low bitrates, which explained the criticism leveled at the FMV-based video games.
The vectors that are quantized in Cinepak are 2×2 pixel blocks. A block can consist of 4 luminance values (grayscale) or of 4 luminance and 2 chrominance values (4:2:0 chroma subsampling). The quantized blocks are stored in two codebooks, named V1 and V4, each with up to 256 entries. The vectors in the V1 codebook represent downscaled 4×4 pixel blocks, while those in the V4 codebook represent 2×2 pixel blocks.
For processing, Cinepak divides a video into key (intra-coded) images and inter-coded images.