For a digital audio signal from a CD, the bit-rate is 1411.2 kbps. Audio compression really consists of two parts. To play the bitstream on your soundcard, you need the second part, called decoding . Decoding takes the bitstream and reconstruct it to a WAVE file. Highest coding efficiency is achieved with algorithms exploiting signal redundancies and irrelevancies in the frequency domain based on a model of the human auditory system.
All coders use the same basic structure.
In its quantization and coding stage, the encoder tries to allocate the available number of data bits in a way to meet both the bitrate and masking requirements. The decoder is much less complex. Its only task is to synthesize an audio signal out of the coded spectral components. The term psychoacoustics describes the characteristics of the human auditory system on which modern audio coding technology is based. The sensitivity of the human auditory systems for audio signals is one of its most significant characteristics.