Codec

A codec is a accessory or computer affairs able of encoding or adaptation a agenda abstracts beck or signal.1234 The chat codec is a blend of "compressor-decompressor" or, added commonly, "coder-decoder". A codec (the program) should not be abashed with a coding or compression architecture or accepted – a architecture is a certificate (the standard), a way of autumn data, while a codec is a affairs (an implementation) which can apprehend or address such files. In practice, however, "codec" is sometimes acclimated about to accredit to formats.

A codec encodes a abstracts beck or arresting for transmission, accumulator or encryption, or decodes it for playback or editing. Codecs are acclimated in videoconferencing, alive media and video alteration applications. A video camera's analog-to-digital advocate (ADC) converts its analog signals into agenda signals, which are again anesthetized through a video compressor for agenda manual or storage. A accepting accessory again runs the arresting through a video decompressor, again a digital-to-analog advocate (DAC) for analog display. The appellation codec is aswell acclimated as a all-encompassing name for a video conferencing unit.

Related concepts

An endec (encoder/decoder) is a agnate yet altered abstraction mainly acclimated for hardware. In the mid 20th century, a "codec" was accouterments that coded analog signals into Pulse-code accentuation (PCM) and decoded them back. Late in the aeon the name came to be activated to a chic of software for converting a part of agenda arresting formats, and including compander functions.

A modem is a abbreviating of modulator/demodulator (modem was alleged dataset by telcos) and converts agenda abstracts from computers to analog for buzz band transmission. On the accepting end the analog is adapted aback to digital. Codecs do the adverse (convert audio analog to agenda and again computer agenda complete aback to audio).

An audio codec converts analog audio signals into agenda signals for manual or storage. A accepting accessory again converts the agenda signals aback to analog application an audio decompressor, for playback. An archetype of this are the codecs acclimated in the complete cards of claimed computers. A video codec accomplishes the aforementioned assignment for video signals.

Compression quality

Lossy codecs: Abounding of the added accepted codecs in the software apple are lossy, acceptation that they abate superior by some bulk in adjustment to accomplish compression. Often, this blazon of compression is around duplicate from the aboriginal uncompressed complete or images, depending on the codec and the settings used.5 Smaller abstracts sets affluence the ache on almost big-ticket accumulator sub-systems such as non-volatile anamnesis and harder disk, as able-bodied as write-once-read-many formats such as CD-ROM, DVD and Blu-ray Disc. Lower abstracts ante aswell abate amount and advance achievement if the abstracts is transmitted.

Lossless codecs: There are aswell abounding lossless codecs which are about acclimated for archiving abstracts in a aeroembolism anatomy while appliance all of the advice present in the aboriginal stream. If attention the aboriginal superior of the beck is added important than eliminating the appropriately beyond abstracts sizes, lossless codecs are preferred. This is abnormally accurate if the abstracts is to abide added processing (for archetype editing) in which case the again appliance of processing (encoding and decoding) on lossy codecs will abase the superior of the consistent abstracts such that it is no best identifiable (visually, audibly or both). Using added than one codec or encoding arrangement successively can aswell abase superior significantly. The abbreviating amount of accumulator accommodation and arrangement bandwidth has a addiction to abate the charge for lossy codecs for some media.

Media codecs

Codecs are generally advised to accent assertive aspects of the media, or their use, to be encoded. For example, a agenda video (using a DV codec) of a sports accident needs to encode motion able-bodied but not necessarily exact colors, while a video of an art display needs to accomplish able-bodied encoding blush and apparent texture.

Audio codecs for corpuscle phones charge to accept actual low cessation amid antecedent encoding and playback; while audio codecs for recording or advertisement can use high-latency audio compression techniques to accomplish college allegiance at a lower bit-rate.

There are bags of audio and video codecs alignment in amount from chargeless to hundreds of dollars or more. This array of codecs can actualize affinity and obsolescence issues. The appulse is lessened for earlier formats, for which chargeless or nearly-free codecs accept existed for a continued time. The earlier formats are generally ill-fitted to avant-garde applications, however, such as playback in baby carriageable devices. For example, raw uncompressed PCM audio (44.1 kHz, 16 bit stereo, as represented on an audio CD or in a .wav or .aiff file) has continued been a accepted beyond assorted platforms, but its manual over networks is apathetic and big-ticket compared with added avant-garde aeroembolism formats, such as MP3.

Many multimedia abstracts streams accommodate both audio and video, and generally some metadata that admittance synchronization of audio and video. Each of these three streams may be handled by altered programs, processes, or hardware; but for the multimedia abstracts streams to be advantageous in stored or transmitted form, they have to be encapsulated calm in a alembic format.

Bitrate

Lower bitrate codecs acquiesce added users, but they aswell accept added distortion. Beyond the antecedent access in distortion, lower bit amount codecs aswell accomplish their lower bit ante by application added circuitous algorithms that accomplish assertive assumptions, such as those about the media and the packet accident rate. Other codecs may not accomplish those aforementioned assumptions. When a user with a low bitrate codec talks to a user with addition codec, added baloney is alien by anniversary transcoding.

Transcoding.

The angle of AVI getting a codec is incorrect as AVI is a alembic format, which abounding codecs ability use (although not to ISO standard). There are aswell added acclaimed containers such as Ogg, ASF, QuickTime, RealMedia, Matroska, DivX Media Architecture and containers authentic as ISO standards, such as MPEG carriage stream, MPEG affairs stream, MP4 and ISO abject media book format.