Video codec

codecvideo decodingcodecsvideovideo encoding and decodinglossless video codecaudio/video codecsencode video streamsformatshardware accelerated video decoding
A video codec is an electronic circuit or software that compresses or decompresses digital video.wikipedia
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Video quality

qualityfull reference metricmodels
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).
Such systems encode video streams and transmit them over various kinds of networks or channels.

Codec

codecsdecoderdecoders
In the context of video compression, "codec" is a concatenation of "encoder" and "decoder"—a device that only compresses is typically called an encoder, and one that only decompresses is a decoder.
A video codec accomplishes the same task for video signals.

Data compression

compressionvideo compressioncompressed
A video codec is an electronic circuit or software that compresses or decompresses digital video.
Most video compression formats and codecs exploit both spatial and temporal redundancy (e.g. through difference coding with motion compensation).

Digital television

digitaldigital TVDTV
MPEG-2 became the standard video format for DVD and SD digital television.
The EU 256 project by the CMTT and ETSI, along with research by Italian broadcaster RAI, developed a DCT video codec that broadcast SDTV at 34Mbps bit-rate and near-studio-quality HDTV at about 70–140 Mbps bit-rate.

Videotelephony

videoconferencingvideo conferencingvideo chat
Video codecs are used in DVD players, Internet video, video on demand, digital cable, digital terrestrial television, videotelephony and a variety of other applications.
Only in the late 20th century with the advent of powerful video codecs combined with high-speed Internet broadband and ISDN service did videotelephony become a practical technology for regular use.

K-Lite Codec Pack

K-Lite
Online video material is encoded by a variety of codecs, and this has led to the availability of codec packs — a pre-assembled set of commonly used codecs combined with an installer available as a software package for PCs, such as K-Lite Codec Pack, Perian and Combined Community Codec Pack.
The K-Lite Codec Pack is a collection of audio and video codecs for Microsoft Windows that enables an operating system and its software to play various audio and video formats generally not supported by the operating system itself.

Comparison of video codecs

Comparison of video encodersvideo
Α video codec is software or a device that provides encoding and decoding for digital video, and which may or may not include the use of video compression and/or decompression.

Moving Picture Experts Group

MPEGMotion Picture Experts GroupMPEG encoding
The most popular video coding standards used for codecs have been the MPEG standards.

Video coding format

video coding standardsvideo codingvideo coding standard
The most popular video coding standards used for codecs have been the MPEG standards. The compressed data format usually conforms to a standard video compression specification.
A specific software or hardware implementation capable of compression and/or decompression to/from a specific video coding format is called a video codec; an example of a video codec is Xvid, which is one of several different codecs which implements encoding and decoding videos in the MPEG-4 Part 2 video coding format in software.

High-definition television

HDTVhigh definitionHD
H.264 is the main video encoding standard for Blu-ray Discs, and is widely used by streaming internet services such as YouTube, Netflix, Vimeo, and iTunes Store, web software such as Adobe Flash Player and Microsoft Silverlight, and various HDTV broadcasts over terrestrial and satellite television.
The EU 256 project by the CMTT and ETSI, along with research by Italian broadcaster RAI, developed a DCT video codec that broadcast near-studio-quality HDTV transmission at about 70–140 Mbps bit-rate.

Combined Community Codec Pack

CCCP
Online video material is encoded by a variety of codecs, and this has led to the availability of codec packs — a pre-assembled set of commonly used codecs combined with an installer available as a software package for PCs, such as K-Lite Codec Pack, Perian and Combined Community Codec Pack.

List of open-source codecs

Open source codecs and containersList of open source codecsfreely-licensed data compression technologies

Subjective video quality

psycho-visual optimizationsratings obtained by human viewerssubjective quality assessment
For example, to test the quality of a video codec, independent variables may be the video encoding software, a target bitrate, and the target resolution of the processed sequence.

Electronic circuit

circuitcircuitryelectronic circuits
A video codec is an electronic circuit or software that compresses or decompresses digital video.

Software

Computer softwareSoftware & Programmingsoftware technology
A video codec is an electronic circuit or software that compresses or decompresses digital video.

Digital video

videodigitaldigitally
A video codec is an electronic circuit or software that compresses or decompresses digital video.

Uncompressed video

uncompressedclean HDMIRAW
It converts uncompressed video to a compressed format or vice versa.

Lossy compression

lossylossy data compressioncompressed
The compression is typically lossy, meaning that the compressed video lacks some information present in the original video.

Latency (engineering)

latencylow latencylow-latency
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).

Magnetic tape

tapetapesanalog tape
Historically, video was stored as an analog signal on magnetic tape.

Compact disc

CDCDsCD single
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.

Engineer

engineersconsulting engineerIr.
Since then, engineers and mathematicians have developed a number of solutions for achieving this goal that involve compressing the digital video data.

Mathematician

mathematiciansapplied mathematicianMathematics
Since then, engineers and mathematicians have developed a number of solutions for achieving this goal that involve compressing the digital video data.

Discrete cosine transform

DCTiDCTinverse discrete cosine transform
In 1974, discrete cosine transform (DCT) compression was introduced by Nasir Ahmed, T. Natarajan and K. R. Rao.

Nasir Ahmed (engineer)

Nasir AhmedN. Ahmed
In 1974, discrete cosine transform (DCT) compression was introduced by Nasir Ahmed, T. Natarajan and K. R. Rao.