Encoding device and method, decoding device and method, and program

An encoding method comprising the steps of:

• dividing an input signal into a plurality of subbands, and generating a low-frequency subband signal including a plurality of subbands on the low-frequency side, and a high-frequency subband signal including a plurality of subbands on the high-frequency side;
• calculating feature amount that represents features of the input signal based on at least one of the low-frequency subband signal and the input signal;
• subjecting the feature amount to smoothing;
• calculating pseudo high-frequency subband power that is an estimated value of power of the high-frequency subband signal based on the smoothed feature amount and a predetermined coefficient;
• calculating high-frequency subband power of the high-frequency subband signal from the high-frequency subband signal, and comparing the high-frequency subband power and the pseudo high-frequency subband power to select a coefficient from a plurality of coefficients;
• encoding coefficient information for obtaining the selected coefficient, and smoothing information relating to the smoothing to generate high-frequency encoded data;
• encoding a low-frequency signal of the input signal to generate low-frequency encoded data;
• and
• multiplexing the low-frequency encoded data and the high-frequency encoded data to obtain an output code string for transmitting to a playback device including a decoding device.

A non-transitory computer-readable medium encoded with a program that, when executed by a computer, causes the computer to execute processing comprising the steps of:

• dividing an input signal into a plurality of subbands, and generating a low-frequency subband signal made up of a plurality of subbands on the low-frequency side, and a high-frequency subband signal made up of a plurality of subbands on the high-frequency side;
• calculating feature amount that represents features of the input signal based on at least any one of the low-frequency subband signal and the input signal;
• subjecting the feature amount smoothing;
• calculating pseudo high-frequency subband power that is an estimated value of power of the high-frequency subband signal based on the smoothed feature amount and a predetermined coefficient;
• calculating high-frequency subband power of the high-frequency subband signal from the high-frequency subband signal, and comparing the high-frequency subband power and the pseudo high-frequency subband power to select any of a plurality of the coefficients;
• encoding coefficient information for obtaining the selected coefficient, and smoothing information relating to the smoothing to generate high-frequency encoded data;
• encoding a low-frequency signal of the input signal to generate low-frequency encoded data;
• and
• multiplexing the low-frequency encoded data and the high-frequency encoded data to obtain an output code string for transmitting to a playback device including a decoding device.

A decoding device comprising:

• demultiplexing means configured to demultiplex input encoded data into low-frequency encoded data, coefficient information for obtaining a coefficient, and smoothing information relating to smoothing;
• low-frequency decoding means configured to decode the low-frequency encoded data to generate a low-frequency signal;
• subband dividing means configured to divide the low-frequency signal into a plurality of subbands to generate a low-frequency subband signal for each of the subbands;
• feature amount calculating means configured to calculate feature amount based on the low-frequency subband signals;
• smoothing means configured to subject the feature amount to smoothing based on the smoothing information;
• and
• generating means configured to generate a high-frequency signal based on the coefficient obtained from the coefficient information, the feature amount subjected to smoothing, and the low-frequency subband signals,
• wherein the low-frequency signal and the high frequency signal produce high sound quality when combined and played back.

A decoding method comprising the steps of:

• demultiplexing input encoded data into low-frequency encoded data, coefficient information for obtaining a coefficient, and smoothing information relating to smoothing;
• decoding the low-frequency encoded data to generate a low-frequency signal;
• dividing the low-frequency signal into a plurality of subbands to generate a low-frequency subband signal for each of the subbands;
• calculating feature amount based on the low-frequency subband signals;
• subjecting the feature amount to smoothing based on the smoothing information;
• and
• generating a high-frequency signal based on the coefficient obtained from the coefficient information, the feature amount subjected to smoothing, and the low-frequency subband signals,
• wherein the low-frequency signal and the high-frequency signal produce high sound quality when combined and played back.

A non-transitory computer-readable medium encoded with a program that, when executed by a computer, causes the computer to execute processing comprising the steps of:

• demultiplexing input encoded data into low-frequency encoded data, coefficient information for obtaining a coefficient, and smoothing information relating to smoothing;
• decoding the low-frequency encoded data to generate a low-frequency signal;
• dividing the low-frequency signal into a plurality of subbands to generate a low-frequency subband signal for each of the subbands;
• calculating feature amount based on the low-frequency subband signals;
• subjecting the feature amount to smoothing based on the smoothing information;
• and
• generating a high-frequency signal based on the coefficient obtained from the coefficient information, the feature amount subjected to smoothing, and the low-frequency subband signals,
• wherein the low-frequency signal and the high-frequency signal produce high sound quality when combined and played back.

An encoding device comprising:

• a subband dividing circuit configured to divide an input signal into a plurality of subbands, and to generate a low-frequency subband signal including a plurality of subbands on the low-frequency side, and a high-frequency subband signal including, a plurality of subbands on the high-frequency side;
• a feature amount calculating circuit configured to calculate feature amount that represents features of the input signal based on at least any one of the low-frequency subband signal and the input signal;
• a smoothing circuit configured to subject the feature amount to smoothing;
• a pseudo high-frequency subband power calculating circuit configured to calculate pseudo high-frequency subband power that is an estimated value of power of the high-frequency subband signal based on the smoothed feature amount and a predetermined coefficient;
• a selecting circuit configured to calculate high-frequency subband power of the high-frequency subband signal from the high-frequency subband signal, and to compare the high-frequency subband power and the pseudo high-frequency subband power to select a coefficient from a plurality of coefficients;
• a high-frequency encoding circuit configured to encode coefficient information for obtaining the selected coefficient, and smoothing information relating to the smoothing to generate high-frequency encoded data;
• a low-frequency encoding circuit configured to encode a low-frequency signal of the input signal to generate low-frequency encoded data;
• and
• a multiplexing circuit configured to multiplex the low-frequency encoded data and the high-frequency encoded data to obtain an output code string for transmitting to a playback device including a decoding device.

A decoding device comprising:

• a demultiplexing circuit configured to demultiplex input encoded data into low-frequency encoded data, coefficient information for obtaining a coefficient, and smoothing information relating to smoothing;
• a low-frequency decoding circuit configured to decode the low-frequency encoded data to generate a low-frequency signal;
• a subband dividing circuit configured to divide the low-frequency signal into a plurality of subbands to generate a low-frequency subband signal for each of the subbands;
• a feature amount calculating circuit configured to calculate feature amount based on the low-frequency subband signals;
• a smoothing circuit configured to subject the feature amount to smoothing based on the smoothing information;
• and
• a generating circuit configured to generate a high-frequency signal based on the coefficient obtained from the coefficient information, the feature amount subjected to smoothing, and the low-frequency subband signals,
• wherein the low-frequency signal and the high-frequency signal produce high sound quality when combined and played back.