MPEG-4 Book, The

11.3. MPEG-4 Additions to AAC

Besides the building blocks provided by MPEG-2 AAC, the MPEG-4 T/F coder includes several extensions in order to enhance coding efficiency and offer new functionalities. Examples of additional building blocks include perceptual noise substitution (PNS), long-term prediction (LTP), and the transform-domain weighted interleave vector quantization (TwinVQ) coding kernel. The low-delay AAC (AAC-LD) coder and the error-resilience (ER) provisions illustrate how new functionalities can be supported by variation/modification of the basic AAC technology. The capability for scalable audio coding deserves particular attention in the context of MPEG-4 (see Section 11.4). Scalability is achieved by introducing concepts of large-step ...