The ISO audio coding standard

An ISO audio coding standard is being developed that will provide an audio quality comparable to that of a compact disc using a reduced bit rate of about 2×128 kb/s for a stereo sound signal instead of 2×706 kb/s. Four coding algorithms have been considered in order to develop the audio coding standard. Two of these coding algorithms have been tested and are outlined. The ASPEC algorithm uses a modified discrete cosine transform with overlapping blocks and dynamic windowing in order to map the input samples into frequency coefficients. The MUSICAM algorithm uses a subband analysis filter bank with 32 equally spaced subbands to map the input samples into frequency coefficients. Concepts for improvement of the coding algorithms are discussed which might be the basis for future ISO activities aiming at a bit rate of only 2×64 kb/s for a stereo sound signal