Cinepak is a

lossy In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data si ...

video codec A video codec is software or hardware that compresses and decompresses digital video. In the context of video compression, '' codec'' is a portmanteau of ''encoder'' and ''decoder'', while a device that only compresses is typically called an ...

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 QuickTime is an extensible multimedia framework developed by Apple Inc., capable of handling various formats of digital video, picture, sound, panoramic images, and interactivity. Created in 1991, the latest Mac version, QuickTime X, is a ...

video suite. One of the first video compression tools to achieve

full motion video Full-motion video (FMV) is a video game narration technique that relies upon pre-recorded video files (rather than sprites, vectors, or 3D models) to display action in the game. While many games feature FMVs as a way to present information duri ...

CD-ROM A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains data. Computers can read—but not write or erase—CD-ROMs. Some CDs, called enhanced CDs, hold both com ...

, it was designed to encode 320×240 resolution video at 1× (150 kbyte/s)

transfer rates. The original name of this codec was Compact Video, which is why its FourCC identifier is CVID. The codec was ported to

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

in 1993. It was also used on fourth- and fifth-generation game consoles, such as the

Atari Jaguar CD The Atari Jaguar CD is a CD-ROM peripheral for the Jaguar video game console. Atari announced a CD-ROM drive for the Jaguar before the console's November 1993 launch. Codenamed Jaguar II during development, the Jaguar CD was released on Septemb ...

Sega CD The Sega CD, released as the in most regions outside North America and Brazil, is a CD-ROM accessory for the Sega Genesis produced by Sega as part of the fourth generation of video game consoles. It was released on December 12, 1991, in Japan ...

Sega Saturn The is a home video game console developed by Sega and released on November 22, 1994, in Japan, May 11, 1995, in North America, and July 8, 1995, in Europe. Part of the fifth generation of video game consoles, it was the successor to the su ...

, and 3DO.

libavcodec libavcodec is a free and open-source library of codecs for encoding and decoding video and audio data. libavcodec is an integral part of many open-source multimedia applications and frameworks. The popular MPV, xine and VLC media players u ...

includes a Cinepak decoder and an encoder, both licensed under the terms of the

LGPL The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

History

It was the primary video codec of early versions of

and Microsoft

Video for Windows Video for Windows was a suite of video playing and editing software introduced by Microsoft in 1992. A runtime version for viewing videos only was made available as a free add-on to Windows 3.1, which then became an integral component of Windows ...

, but was later superseded by

Sorenson Video Sorenson Media was an American software company specializing in video encoding technology. Established in December 1995 as Sorenson Vision, the company developed technology which was licensed and ultimately acquired from Utah State University. T ...

, Intel Indeo, and most recently

MPEG-4 Part 2 MPEG-4 Part 2, MPEG-4 Visual (formally ISO/IEC 14496-2) is a video compression format developed by the Moving Picture Experts Group (MPEG). It belongs to the MPEG-4 ISO/IEC standards. It uses block-wise motion compensation and a discrete cosi ...

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 Vector quantization (VQ) is a classical quantization technique from signal processing that allows the modeling of probability density functions by the distribution of prototype vectors. It was originally used for data compression. It works by di ...

, which is a significantly different algorithm from the discrete cosine transform (DCT) algorithm used by most current codecs (in particular the

MPEG The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio, video, graphics, and genomic data; and transmission and f ...

family, as well as

JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and imag ...

). This permitted implementation on relatively slow CPUs (video encoded in Cinepak will usually play fine even on a 25 MHz

Motorola 68030 The Motorola 68030 ("''sixty-eight-oh-thirty''") is a 32-bit microprocessor in the Motorola 68000 family. It was released in 1987. The 68030 was the successor to the Motorola 68020, and was followed by the Motorola 68040. In keeping with general ...

, 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

bitrate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction ...

s, 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. In key images the codebooks are transmitted from scratch, while in inter-coded images codebook entries are selectively updated. Each image is further divided into a number of horizontal bands. The codebooks can be updated on a per-band basis. Each band is divided into 4×4 pixel blocks. Each block can be coded either from the V1 or from the V4 codebook. When coding from the V1 codebook, one codebook index per 4×4 block is written to the bitstream, and the corresponding 2×2 codebook entry is upscaled to 4×4 pixels. When coding from the V4 codebook, four codebook indices per 4×4 block are written to the bitstream, one for each 2×2 subblock. Alternatively to coding from the V1 or the V4 codebook, a 4×4 block in an inter-coded image can be skipped. A skipped block is copied unchanged from the previous frame in a

conditional replenishment Conditional (if then) may refer to: * Causal conditional, if X then Y, where X is a cause of Y *Conditional probability, the probability of an event A given that another event B has occurred * Conditional proof, in logic: a proof that asserts a ...

fashion. The data rate can be controlled by adjusting the rate of key frames and by adjusting the permitted error in each block.

References

External links

Technical Description of the Cinepak Codec

Cinepak - MultimediaWiki

Cinepak Official Website

Cinepak Decoder - FFmpeg
{{Compression Software Implementations Video codecs