METHOD AND APPARATUS FOR EXTRACTING IMPORTANT SPECTRAL COMPONENT OF AUDIO SIGNAL, AND METHOD AND APPARTUS FOR ENCODING/DECODING AUDIO SIGNAL USING IT

摘要

A method and an apparatus for extracting an ISC(Important Spectral Component) of an audio signal, and a method and apparatus for coding/decoding an audio signal using the same are provided to extract ISC of an audio signal belonging to a frequency band having harmonic characteristics based on a harmonic model and code/decode them, to thus select a more ISC at the same bit rate. A T/F conversion unit(110) converts an input audio signal of a time domain into an audio signal of a frequency domain. A frequency decomposing unit(120) decomposes an audio signal according to each frame into certain sub-bands. A harmonic characteristics determining unit(130) determines whether each sub-band unit has harmonic characteristics by using a frequency shifting method. A harmonic model-based ISC extracting unit extracts an ISC from an audio signal having harmonic characteristics, and a harmonic parameter from the ISC. A psychological sound model-based ISC extracting unit(150) calculates an SMR(Signal to Mask Ratio) in consideration of psychoacoustic characteristics with respect to the audio signal converted into the frequency domain, and extracts an ISC by using the calculated SMR.