compression

The driving force to develop AAC was the quest for an efficient coding method for surround signals, like 5-channel signals (left, right, centre, left-surround, and right-surround) as being used in cinemas today. There have been algorithms for these signals in MPEG-2 for quite a while. Optimum efficiency, however, was not reached due to technical and historical reasons. Therefore, the set aim was a considerable decrease of necessary bit rate.


MPEG-2 AAC is the consequent continuation of the truly successful coding method ISO/MPEG Audio Layer-3 developed in Erlanger. The extensive co-operation with international partners and the insight derived from Layer-3 paved the way for this coding method, which is unique at this present stage. The appropriate incorporation of high coding gain and great flexibility opens up a wide field of applications. With sampling frequencies between 8 kHz and 96 kHz and any number of channels between 1 and 48, the method is well prepared for future develop...