Low-delay and Ultra-Low-Delay coding in MPEG-4 AAC

Abstract

MPEG Advanced Audio Coding (AAC) supports 2048-sample windows which give quiet long delay (about 50ms for coder). In this paper we propose AAC Low Delay codecs with 1024-sample window (23ms delay) and Ultra Low Delay codecs with 512-sample window which gives delay about 12ms. LD and ULD can be used in real-time coding e.g. in robots control and very fast voice communication. This design is complete coders and decoders with simple bit-rate control algorithm. Proposed design was implemented in FPGA devices.