Patent ID: 8160868

Claim:
A scalable decoding apparatus that decodes core layer encoded information and enhancement layer encoded information comprising enhancement layer gain coefficients, the scalable decoding apparatus comprising: a core layer decoder that generates a core layer decoded speech signal by decoding core layer coded data; a current frame power calculator that calculates a power of a current frame of the core layer decoded speech signal generated by the core layer decoder; a previous frame power storer that stores the current frame power calculated by the current frame power calculator by a number of essential frames; a change detector that detects a change in power of the core layer decoded speech signal by comparing the current frame power calculated by the current frame power calculator with a previous frame power stored in the previous frame power storer; a setter that variably sets a degree of attenuation according to the detected change in power so as to (i) set the degree of attenuation greater when a power decrease of the core layer decoded speech signal is detected than when a power increase of the core layer decoded speech signal is detected or (ii) set the degree of attenuation less when the power increase of the core layer decoded speech signal is detected than when the power decrease of the core layer decoded speech signal is detected; and an attenuator that attenuates enhancement layer gain coefficients for a second interval earlier than the first interval according to the set degree of attenuation and interpolates enhancement layer gain coefficients for the first interval, when enhancement layer encoded information of a first interval is lost.