Bandwidth extension system and approach

摘要

A method of performing BandWidth Extension (BWE) includes a frequency band shifting approach to generate an extended high band signal in time domain and a gain determination approach of controlling the energy of the extended high band. The proposed approach allows shifting any size of low band to any size of high band. The BWE scaling gain is estimated by using available filter bank coefficients with extremely low bit rate or without costing any bit, combining three possible gain factors.

主权项

1. A method of extending a bandwidth of an audio signal with a time domain approach, the method comprising:
receiving a baseband audio signal having a first frequency content within a first frequency band that extends from zero frequency to a first positive frequency; up-sampling the baseband audio signal to produce a baseband up-sampled signal; mirroring the baseband audio signal to produce a baseband mirrored signal, wherein the baseband mirrored signal comprises second frequency content within the first frequency band that is mirrored over frequency with respect to the first frequency content; up-sampling and low-pass filtering the baseband mirrored signal using non-symmetric low-pass-filtering to produce a high band mirrored signal; and mirroring the high band mirrored signal to produce an extra high band signal; and generating a bandwidth-extended audio signal by summing the extra high band signal and the baseband up-sampled signal, wherein the steps of up-sampling the baseband audio signal, mirroring the baseband audio signal, up-sampling and low-pass filtering the baseband mirrored signal, mirroring the high band mirrored signal, and generating the bandwidth-extended audio signal are performed in a time domain using a hardware-based decoder.