Audio codec

An audio codec is a device or computer program capable of coding or decoding a digital data stream of audio.

In software, an audio codec is a computer program implementing an algorithm that compresses and decompresses digital audio data according to a given audio file or streaming media audio coding format. The objective of the algorithm is to represent the high-fidelity audio signal with minimum number of bits while retaining the quality. This can effectively reduce the storage space and the bandwidth required for transmission of the stored audio file. Most codecs are implemented as libraries which interface to one or more multimedia players.

In hardware, audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. In other words, it contains both an analog-to-digital converter (ADC) and digital-to-analog converter (DAC) running off the same clock. This is used in sound cards that support both audio in and out, for instance.

Digital audio

Digital audio is technology that can be used to record, store, generate, manipulate, and reproduce sound using audio signals that have been encoded in digital form. Following significant advances in digital audio technology during the 1970s, it gradually replaced analog audio technology in many areas of sound production, sound recording (tape systems were replaced with digital recording systems), sound engineering and telecommunications in the 1990s and 2000s.

A microphone converts sound (a singer's voice or the sound of an instrument playing) to an analog electrical signal, then an analog-to-digital converter (ADC)—typically using pulse-code modulation—converts the analog signal into a digital signal. This digital signal can then be recorded, edited and modified using digital audio tools. When the sound engineer wishes to listen to the recording on headphones or loudspeakers (or when a consumer wishes to listen to a digital sound file of a song), a digital-to-analog converter performs the reverse process, converting a digital signal back into an analog signal, which analog circuits amplify and send to a loudspeaker.

Audio

Audio may refer to:

Sound

Entertainment

Computing

See also

Decoder

Decoder may refer to:

Data format converters

Music

Other uses

See also

5.1 surround sound

5.1 surround sound ("five point one") is the common name for six channel surround sound audio systems. 5.1 is the most commonly used layout in home cinema. It uses five full bandwidth channels and one low-frequency effects channel (the "point one").Dolby Digital, Dolby Pro Logic II, DTS, and SDDS are all common 5.1 systems. 5.1 is also the standard surround sound audio component of digital broadcast and music.

All 5.1 systems use the same speaker channels and configuration, having a front left and right, a center channel, two surround channels and a subwoofer.

History

5.1 dates back to 1976 when Dolby Labs modified the track usage of the six analogue magnetic soundtracks on Todd-AO 70 mm film prints. The Dolby application of 1976 (released on the film, Logan's Run) did not use split surrounds, and thus was not 5.1. Dolby's use of split surrounds, and the introduction of the 5.1 format on optical prints started in 1979 with Apocalypse Now. Instead of the five screen channels and one surround channel of the Todd-AO format, Dolby Stereo 70 mm Six Track provided three screen channels, two surround channels and a low-frequency enhancement channel.