Cinepak is a video codec developed by Peter Barrett in SuperMac Technologies, and released in 1991 , and then in 1992 in the QuickTime container in Apple computers . It was designed to encode video with a resolution of 320x240 with a single-speed CD-ROM (150 kb / s). In 1993, the codec was ported to the Microsoft Windows platform . It was also used in the first and a little in the second generation of game consoles CD-ROM, such as the Atari Jaguar CD, Sega Mega-CD , Sega Saturn and 3DO Interactive Multiplayer .
It was the main video codec of earlier versions of QuickTime and Microsoft Video for Windows , but was later replaced by Sorenson Video , Intel Indeo , and then MPEG-4 and H.264 . [1] [2] However, Cinepak compressed movies tend to still play in most media players.
Cinepak coding is based on the vector quantization method, which differs significantly from the discrete cosine transform (DCT) algorithm used in the most common codecs (in particular, the MPEG family, as well as JPEG ). This made it possible to implement coding on relatively slow processors (video encoded in Cinepak was well reproduced even on a 25 MHz Motorola 68030 processor, in consoles such as the Sega CD, slower processors, for example, 12.5 MHz 68000, are commonly used), but as a rule, led to the appearance of block artifacts at low bitrates , this explains the criticism of the FMV- based video games.
In the Cinepak encoder, the video is divided into key frames and intra coding frames. Each frame is divided into a series of horizontal stripes, which have separate 256-color palettes and are transmitted to key frames. Each group is divided into blocks of 4x4 pixels. The compressor uses a quantization vector to determine one or two color palette groups that best fit each block, and encodes a series of blocks as one or two bytes for a color plus a 16-bit vector that determines which colors each pixel receives, as well as in texture compression S3. The data transfer rate can be controlled within narrow limits, adjusting the ratio of key frames and frames with internal coding, and adjusting the percentage of errors allowed in each block and the length of the series of blocks. The compression ratio is always around 10: 1, so setting a data transfer rate limit above this value will not improve the image quality or the actual bit rate. [2]
The original name of this codec was CompactVideo, so in FourCC the CVID was set for it.
Cinepak files are usually about 70% larger than MPEG-4 or Ogg files of similar quality.
Notes
- ↑ Jennifer Niederst Robbins. Web Design in a Nutshell: A Desktop Quick Reference . - O'Reilly Media, Inc., February 28, 2006. - P. 627. - ISBN 978-0-596-00987-8 .
- 2 1 2 Apple Computer, Inc. QuickTime for the Web: For Windows and MacIntosh . - Morgan Kaufmann, 2004. - P. 328. - ISBN 978-1-55860-904-4 .