Encoder, decoder, and method therefor

摘要

Provided is an encoder which can effectively encode/decode spectrum data of a broad frequency signal in a high frequency range, can dramatically reduce the number of the arithmetic operations to be performed, and can improve the quality of the decoded signal. The encoder comprises a first layer coding unit (202) which encodes an input signal in a low frequency range below a predetermined frequency to generate first coded information, a first layer decoding unit (203) which decodes the first coded information to generate a decoded signal, and a second layer coding unit (206) which splits the input signal in a high frequency range above a predetermined frequency, into a plurality of sub-bands, presumes the respective sub-hands from the input signal or decoded signal, partially selects a spectrum component within each sub-band, and calculates an amplitude adjustment parameter used to adjust the amplitude of the selected spectrum component to thereby generate second coding information.

主权项

1. An encoding apparatus comprising:
a first encoder structured to generate first encoded information by encoding a lower frequency part of an input signal equal to or lower than a predetermined frequency; a decoder structured to generate a decoded signal by decoding the first encoded information; and a second encoder structured to generate second encoded information by dividing a high frequency part of the input signal higher than the predetermined frequency into a plurality of sub-bands, estimating the plurality of sub-bands respectively from the decoded signal, selecting a spectrum component within each of the sub-bands, and calculating a second amplitude adjustment parameter for adjusting an amplitude for the selected spectrum component, the second amplitude adjustment parameter being a correlation value of the selected spectrum component and the input signal in a logarithmic domain, wherein the second encoder comprises:
a similar part searcher structured to search for a band which is most similar to a spectrum of each of the plurality of sub-bands and a first amplitude adjustment parameter from a spectrum of the decoded signal;an amplitude value searcher structured to search for, for each of the sub-bands, a spectrum component having a maximum amplitude value for a spectrum of a high frequency that is estimated by the most similar band and the first amplitude adjustment parameter;a spectrum component selector structured to select a spectrum component that is present in a region that has a wider bandwidth than a bandwidth of the spectrum component having the maximum amplitude value, the spectrum component having the maximum amplitude value being located at the center of the region; andan amplitude adjustment parameter calculator structured to calculate the second amplitude adjustment parameter that is the correlation value of the selected spectrum component and the input signal in a logarithmic domain, for the selected spectrum component.