ENHANCING PERCEPTUAL PERFORMANCE OF SBR AND RELATED HFR CODING METHODS BY ADAPTIVE NOISE-FLOOR ADDITION AND NOISE SUBSTITUTION LIMITING

摘要

The present proposes new methods and an apparatus for enhancement of source coding systems utilising high frequency reconstruction (HFR). It addresses the problem of insufficient noise contents in a reconstructed highband, by Adaptive Noise-floor Addition. It also introduces new methods for enhanced performance by means of limiting unwanted noise, interpolation and smoothing of envelope adjustment amplification factors. The present invention is applicable to both speech coding and natural audio coding systems.