Cinepak
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Image:Cinepak.png Cinepak is a video codec, developed by Radius Inc to accommodate 1x (150 kbyte/s) CD-ROM transfer rates.
It was the primary video codec of early versions of QuickTime and Microsoft Video for Windows, but was later superseded by Sorenson Video, Intel Indeo, and most recently MPEG-4 and h.264.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, but tended to result in blocky artifacting at low bitrates.
Cinepak divides a movie into key images and intra-coded images. Each image is divided into a number of horizontal bands which have individual 256-color palettes transferred in the key images. Each band is subdivided into 4x4 pixel blocks. The compressor uses vector quantization to determine the one or two band palette colors which best match each block and encodes runs of blocks as either one color byte or two color bytes plus a 16-bit vector which determines which pixel gets which color. The data rate can be controlled within a narrow range by adjusting the rate of key versus intra-coded frames and by adjusting the permitted error in each block and the block run-length.
External links
- Compression Technologies, Inc. - current developers of Cinepak
- Technical Description of the Cinepak CodecTemplate:Tech-stub