It was succeeded in 1994 by MPEG-2/ H.262, which was developed by a number of companies, primarily Sony, Thomson and Mitsubishi Electric. MPEG-1 was developed by the Motion Picture Experts Group (MPEG) in 1991, and it was designed to compress VHS-quality video. The most popular video coding standards used for codecs have been the MPEG standards. Since H.261, DCT compression has been adopted by all the major video coding standards that followed. H.261 was the first practical video coding standard, and was developed by a number of companies, including Hitachi, PictureTel, NTT, BT, and Toshiba, among others. During the late 1980s, a number of companies began experimenting with DCT lossy compression for video coding, leading to the development of the H.261 standard. In 1974, discrete cosine transform (DCT) compression was introduced by Nasir Ahmed, T. Since then, engineers and mathematicians have developed a number of solutions for achieving this goal that involve compressing the digital video data. Because of the large amount of storage and bandwidth needed to record and convey raw video, a method was needed to reduce the amount of data used to represent the raw video. Around the time when the compact disc entered the market as a digital-format replacement for analog audio, it became feasible to also store and convey video in digital form. Historically, video was stored as an analog signal on magnetic tape. There are complex relationships between the video quality, the amount of data used to represent the video (determined by the bit rate), the complexity of the encoding and decoding algorithms, sensitivity to data losses and errors, ease of editing, random access, and end-to-end delay ( latency).įurther information: Video coding format § History A consequence of this is that decompressed video has lower quality than the original, uncompressed video because there is insufficient information to accurately reconstruct the original video. The compression is typically lossy, meaning that the compressed video lacks some information present in the original video. The compressed data format usually conforms to a standard video coding format. In the context of video compression, codec is a portmanteau of encoder and decoder, while a device that only compresses is typically called an encoder, and one that only decompresses is a decoder.
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JSTOR ( April 2011) ( Learn how and when to remove this template message)Ī video codec is software or hardware that compresses and decompresses digital video.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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