Audio signal coding apparatus, audio signal decoding apparatus, audio signal coding method, and audio signal decoding method

An audio signal decoding apparatus for decoding coded information, the audio signal decoding apparatus comprising:

• a memory that stores instructions;
• and
• at least a processor that, when executing the instructions stored in the memory, performs operations comprising:
• demultiplexing the coded information into first coded information, second coded information, quantized sub-band energies for each sub-band among a plurality of sub-bands, and an analysis result for a tonality calculated for each sub-band among the plurality of sub-bands;
• selecting a second sub-band on which decoding is performed by a second decoder from among the plurality of sub-bands on the basis of the analysis result for the tonality and the quantized sub-band energy, and determining a first number of bits to be allocated to a first sub-band among the plurality of sub-bands, on which decoding is performed by a first decoder;
• and
• generating and outputting an output audio signal by performing a transform on a spectrum output from the second decoder into a time domain,
• wherein
• the first decoder generates a first decoded spectrum by decoding the first coded information using the first number of bits, and
• the second decoder generates a second decoded information by decoding the second coded information, and
• the second decoder generates a reconstructed spectrum by performing decoding using the second decoded information and the first decoded spectrum.

An audio signal coding method comprising:

• generating a spectrum comprising performing a transform on an input audio signal into a frequency domain,
• dividing the spectrum into a plurality of sub-bands, which are predetermined frequency bands, and outputting sub-band spectral samples;
• obtaining, for each sub-band of the plurality of sub-bands, a quantized sub-band energy;
• analyzing a tonality of the sub-band spectral samples and outputting an analysis result;
• selecting a second sub-band from among the plurality of sub-bands on the basis of the analysis result for the tonality and the quantized sub-band energy;
• determining a first number of bits to be allocated to a first sub-band among the plurality of sub-bands;
• generating first coded information by coding a sub-band spectral sample among the sub-band spectral samples that is included in the first sub-band by a first coding method using the first number of bits;
• generating second coded information by coding a sub-band spectral sample among the sub-band spectral samples that is included in the second sub-band by using a second coding method wherein the second coding method is configured for calculating lag information for the second subband;
• and
• multiplexing together and outputting the first coded information and the second coded information.

An audio signal decoding method for decoding coded information, the audio signal decoding method comprising:

• demultiplexing the coded information into first coded information, second coded information, quantized sub-band energies for each sub-band among a plurality of sub-bands, and an analysis result for a tonality calculated for each sub-band among the plurality of sub-bands;
• selecting a second sub-band from among the plurality of sub-bands on the basis of the analysis result for the tonality and the quantized sub-band energy;
• determining a first number of bits to be allocated to a first sub-band among the plurality of sub-bands;
• generating a first decoded spectrum by decoding the first coded information using the first number of bits;
• generating a second decoded information by decoding the second coded information;
• generating a reconstructed spectrum by performing decoding using the second decoded information and the first decoded spectrum;
• and
• generating and outputting an output audio signal by performing a transform on the reconstructed spectrum into a time domain.