Spectral band replication tool for very low delay audio coding applications

In this paper a Spectral Band Replication (SBR) tool for low delay audio applications is presented. One goal of this enhancement tool is to reduce the needed bit rate for the representation of audio data using an arbitrary audio codec. Another goal is to keep the algorithmic delay as low as possible. A low coding delay is essential for instance for real time applications like distributed music production under live conditions or telephone conferencing. The low delay SBR approach proposed in this paper uses techniques developed for speech coding purposes and is associated with artificial bandwidth extension methods, particularly spectral folding. Further, the tool exclusively operates in the time domain using prediction methods and adaptive filters in order to avoid additional delay which can be caused by using a filter bank.