Bandwidth Extension Method, Bandwidth Extension Apparatus, Program, Integrated Circuit, and Audio Decoding Apparatus

摘要

Provided is a band enhancement method that can reduce the calculation amounts for enhancing bands and further can suppress the quality degradation of enhanced bands. The band enhancement method comprises the steps of: transforming a low frequency band signal to a QMF range, thereby generating a first low frequency QMF spectrum (S11); applying mutually different shift factors to the low frequency band signal, thereby generating a plurality of pitch-shifted signals (S12); performing a time decompression in the QMF range, thereby generating a high frequency QMF spectrum (S13); modifying the high frequency QMF spectrum (S14); and combining the modified high frequency QMF spectrum with the first low frequency QMF spectrum (S15).