perceptual audio coding (PAC)

The principle of Perceptual Audio Coding (PAC) was developed by Bell Labs (Lucent) in the late 1990s. It is an audio compression for analog music, speech and other low frequency signals.

PAC codecs digitize the analog audio signals into a digital format and have their highest performance already at 96 kbit/s, which makes them particularly suitable for digital audio broadcasting( DAB), HD radio and Internet radio. This data rate is to be reduced to 64 kbit/s in further development. The audio quality is equivalent to that of compact discs, and the compression ratio is 1:15.

PAC codecs work according to models of psychoacoustics and filter irrelevantinformation from the audio signal. PAC compression is similar to Advanced Audio Coding( AAC), both use the same design elements.

In the enhanced version ePAC the files are encrypted with 256 bits. ePAC is very fast, but can only be generated and played back by some proprietary codecs. The quality is described as very high. As with PAC coding, the compression ratio is 1:15.