Codec

codecsdecoderdecodersdecodingencoding and decodingessencemultimedia codecAudio CodecsCoder-Decoder / Compressor-Decompressor / Compression-Decompressiondecoding algorithm
A codec is a device or computer program for encoding or decoding a digital data stream or signal.wikipedia
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Videotelephony

videoconferencingvideo conferencingvideo chat
Codecs are used in videoconferencing, streaming media, and video editing applications.
The development of advanced video codecs, more powerful CPUs, and high-bandwidth Internet telecommunication services in the late 1990s allowed videophones to provide high quality low-cost colour service between users almost anyplace in the world that the Internet is available.

Encoder

encodingencodersencoded
A codec is a device or computer program for encoding or decoding a digital data stream or signal.

Audio codec

audio codecscodecaudio
An audio codec converts analog audio signals into digital signals for transmission or encodes them for storage.
An audio codec is a codec (a device or computer program capable of encoding or decoding a digital data stream) that encodes or decodes audio.

Video codec

codecvideo decodingcodecs
A video codec accomplishes the same task for video signals.
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.

JPEG

JPG.jpgJPG/JPEG
The most widely used lossy data compression technique in digital media is based on the discrete cosine transform (DCT), used in compression standards such as JPEG images, H.26x and MPEG video, and MP3 and AAC audio.
The JPEG standard specifies the codec, which defines how an image is compressed into a stream of bytes and decompressed back into an image, but not the file format used to contain that stream.

MP3

.mp3MP3 downloadMP3 files
The most widely used lossy data compression technique in digital media is based on the discrete cosine transform (DCT), used in compression standards such as JPEG images, H.26x and MPEG video, and MP3 and AAC audio.
In 1978, Bishnu S. Atal and Manfred R. Schroeder at Bell Labs proposed an LPC speech codec, called adaptive predictive coding, that used a psychoacoustic coding algorithm exploiting the masking properties of the human ear.

Video editing

editingeditededitor
Codecs are used in videoconferencing, streaming media, and video editing applications.
Content is ingested and recorded natively with the appropriate codec that the video editing software uses to process captured footage.

DV

MiniDVDVCAMDVCPRO
For example, a digital video (using a DV codec) of a sports event needs to encode motion well but not necessarily exact colors, while a video of an art exhibit needs to encode color and surface texture well.
In 2003, DV was joined by a successor format HDV, which used the same tape format with a different video codec.

Advanced Audio Coding

AACAAC-LCMPEG-4 AAC
The most widely used lossy data compression technique in digital media is based on the discrete cosine transform (DCT), used in compression standards such as JPEG images, H.26x and MPEG video, and MP3 and AAC audio.
However, a patent license is required for all manufacturers or developers of AAC codecs.

Digital container format

container formatcontainercontainer formats
Each of these three streams may be handled by different programs, processes, or hardware; but for the multimedia data streams to be useful in stored or transmitted form, they must be encapsulated together in a container format. Audio Video Interleave (AVI) is sometimes erroneously described as a codec, but AVI is actually a container format, while a codec is a software or hardware tool that encodes or decodes audio or video into or from some audio or video format.
This may be caused by the program lacking the required decoding algorithm.

Latency (audio)

latencydelaylow-latency
Audio codecs for cell phones need to have very low latency between source encoding and playback.
In all systems, latency can be said to consist of three elements: codec delay, playout delay and network delay.

Data compression

compressionvideo compressioncompressed
In contrast, audio codecs for recording or broadcast can use high-latency audio compression techniques to achieve higher fidelity at a lower bit-rate.
Audio compression algorithms are implemented in software as audio codecs.

Ogg

OGM.oggOgg Writ
There are also other well-known container formats, such as Ogg, ASF, QuickTime, RealMedia, Matroska, and DivX Media Format.
Because the format is free, and its reference implementation is not subject to restrictions associated with copyright, Ogg's various codecs have been incorporated into a number of different free and proprietary media players, both commercial and non-commercial, as well as portable media players and GPS receivers from different manufacturers.

List of codecs

video codecsList of multimedia (audio/video) codecsaudio codec
The following is a list of compression formats and related codecs.

Advanced Systems Format

ASF.asf.wmv
There are also other well-known container formats, such as Ogg, ASF, QuickTime, RealMedia, Matroska, and DivX Media Format.
The format does not specify how (i.e. with which codec) the video or audio should be encoded; it just specifies the structure of the video/audio stream.

List of open-source codecs

Open source codecs and containersList of open source codecsfreely-licensed data compression technologies
This is a listing of open-source implementations of media formats—usually called codecs.

Audio Video Interleave

AVI.aviDV AVI
Audio Video Interleave (AVI) is sometimes erroneously described as a codec, but AVI is actually a container format, while a codec is a software or hardware tool that encodes or decodes audio or video into or from some audio or video format.
By way of the RIFF format, the audio-visual data contained in the "movi" chunk can be encoded or decoded by software called a codec, which is an abbreviation for (en)coder/decoder.

QuickTime

QuickTime PlayerQuickTime XApple QuickTime
There are also other well-known container formats, such as Ogg, ASF, QuickTime, RealMedia, Matroska, and DivX Media Format.
The original video codecs included:

Video coding format

video coding standardsvideo codingvideo coding standard
As an analogy, the video coding format H.264 (specification) is to the codec OpenH264 (specific implementation) what the C Programming Language (specification) is to the compiler GCC (specific implementation).

Delta modulation

delta PCMDM
Two principal techniques are used in codecs, pulse-code modulation and delta modulation.

Lossy compression

lossylossy data compressioncompressed
Many popular codecs are lossy.

Pulse-code modulation

PCMLPCMLinear PCM
Two principal techniques are used in codecs, pulse-code modulation and delta modulation. In the mid-20th century, a codec was a device that coded analog signals into digital form using pulse-code modulation (PCM).
The device that performs the coding and decoding function in a telephone (or other circuit) is called a codec.

MPEG-4 Part 14

MP4M4A.mp4
MPEG transport stream, MPEG program stream, MP4, and ISO base media file format are examples of container formats that are ISO standardized.

Computer program

programprogramscomputer programs
A codec is a device or computer program for encoding or decoding a digital data stream or signal.

Decoding methods

syndrome decodingsyndromedecoding
A codec is a device or computer program for encoding or decoding a digital data stream or signal.