Decoding device and decoding method

A decoding method comprising:

• separating a first signal obtained by performing down-mix on original signals of a plurality of channels, a residual signal representing a component of a difference between the original signals and the first signal, and spatial information representing the relationship among the original signals of the plurality of channels from an input signal which is obtained by multiplexing the first signal, the residual signal, and the spatial information and decoding the separated encoded first signal, the encoded residual signal, and the encoded spatial information;
• generating a decorrelation signal, by a computer processor, as decorrelation of the first signal decoded by the decoding;
• determining using the residual signal whether a level of the residual signal decoded by the decoding is equal to or smaller than a predetermined residual threshold value;
• generating a second signal corresponding to the decoded residual signal when the determining using the residual signal determines that the level of the residual signal is larger than the residual threshold value whereas generate a second signal by replacing the decoded residual signal by the decorrelation signal generated by the generating of the decorrelation signal when the determining using the residual signal determines that the level of the residual signal is equal to or smaller than the residual threshold value;
• and
• generating an output signal by decoding the input signal in accordance with the first signal decoded by the decoding, the second signal generated by the generating of the second signal, and the spatial information decoded by the decoding.

A computer-readable storage medium storing a decoding program that causing a computer to execute a process comprising:

• separating a first signal obtained by performing down-mix on original signals of a plurality of channels, a residual signal representing a component of a difference between the original signals and the first signal, and spatial information representing the relationship among the original signals of the plurality of channels from an input signal which is obtained by multiplexing the first signal, the residual signal, and the spatial information and decoding the separated encoded first signal, the encoded residual signal, and the encoded spatial information;
• generating a decorrelation signal as decorrelation of the first signal decoded by the decoding;
• determining using the residual signal whether a level of the residual signal decoded by the decoding is equal to or smaller than a predetermined residual threshold value;
• generating a second signal corresponding to the decoded residual signal when the determining using the residual signal determines that the level of the residual signal is larger than the residual threshold value whereas generate a second signal by replacing the decoded residual signal by the decorrelation signal generated by the generating of the decorrelation signal when the determination using the residual signal determines that the level of the residual signal is equal to or smaller than the residual threshold value;
• and
• generating an output signal by decoding the input signal in accordance with the first signal decoded by the decoding, the second signal generated by the generating of the second signal, and the spatial information decoded by the decoding.

A decoding device comprising:

• a processor;
• and
• a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute,
• separating a first signal obtained by performing down-mix on original signals of a plurality of channels, a residual signal representing a component of a difference between the original signals and the first signal, and spatial information representing the relationship among the original signals of the plurality of channels from an input signal which is obtained by multiplexing the first signal, the residual signal, and the spatial information and decoding the separated encoded first signal, the encoded residual signal, and the encoded spatial information;
• generating a decorrelation signal as decorrelation of the first signal decoded by the decoding;
• determining using the residual signal whether a level of the residual signal decoded by the decoding is equal to or smaller than a predetermined residual threshold value;
• generating a second signal corresponding to the decoded residual signal when the determining using the residual signal determines that the level of the residual signal is larger than the residual threshold value whereas generate a second signal by replacing the decoded residual signal by the decorrelation signal generated by the generating of the decorrelation signal when the determining using the residual signal determines that the level of the residual signal is equal to or smaller than the residual threshold value;
• and
• generating an output signal by decoding the input signal in accordance with the first signal decoded by the decoding, the second signal generated by the generating of the second signal, and the spatial information decoded by the decoding.