SOUND QUALITY IMPROVING METHOD AND DEVICE, SOUND DECODING METHOD AND DEVICE, AND MULTIMEDIA DEVICE EMPLOYING SAME

摘要

A sound quality improving method comprises the steps of: generating a high frequency signal by using a low frequency signal in a time domain; coupling a low frequency signal and the generated high frequency signal; converting the coupled signal to a frequency domain; determining the class of a decoded audio signal; estimating an envelope from a low frequency spectrum obtained in the converting step, based on class; and generating a final high frequency spectrum by applying the estimated envelope to a high frequency spectrum obtained in the converting step.