Codec

What is a Codec?

Codecs can be defined in hardware and in software. A hardware audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. This device works by combining an ADC (analog to digital converter) with a DAC (digital to analog converter) utilising the same clock signal. Hardware audio codecs send and receive digital data using buses such as I²S, SPI, I²C, PCI, etc. Most commonly the digital data is linear PCM (pulse code modulation) These hardware codecs are widely used in PC soundcards, processing both audio in and out signals. Heard of a zip file? Well, a software audio codec is an algorithm that compresses and decompresses digital audio data according to a given audio file or streaming media audio coding format. The algorithm represents the high-fidelity audio signals with the minimum number of bits whilst retaining the best possible quality. This reduces storage space and also the bandwidth that is required to transmit the audio files. Most software codecs are implemented as libraries that interface to one or more multimedia players. Most modern audio compression algorithms are based on MDCT (modified discrete cosine transform) coding and LPC (linear predictive coding).