Encoding device, decoding device, encoding method, decoding method, and non-transitory computer-readable recording medium

A decoding device that receives a first encoded signal, a high-band encoded signal comprising lag information, and a band energy encoded signal representing a quantized band energy for each subband of a plurality of subbands, the decoding device comprising:

• a first decoder, which in operation, decodes the first encoded signal to generate a low-band decoded signal;
• a second decoder, which in operation, decodes the high-band encoded signal to generate a wide-band decoded signal by using the low-band decoded signal;
• and
• a third decoder, which in operation, decodes the band energy encoded signal to generate a quantized band energy for each subband of the plurality of subbands,
• wherein the second decoder comprises:
• a bandwidth extending unit that copies a low-band non-tonal signal derived from the low-band decoded signal to a high band by using the lag information obtained by decoding the high-band encoded signal to obtain a high-band non-tonal signal;
• a tonal signal energy estimating unit that estimates an energy of a high-band tonal signal from an energy of the high-band non-tonal signal and the quantized band energy for a subband of the plurality of subbands;
• and
• an addition unit that adds the low-band non-tonal signal, the high-band non-tonal signal, a low-band tonal signal derived from the low-band decoded signal, and a high-band tonal signal derived from the low-band decoded signal and the lag information to generate a wide-band decoded signal.

An encoding method comprising:

• encoding a low-band signal from a voice or audio input signal to generate a first encoded signal;
• decoding the first encoded signal to generate a low-band decoded signal;
• encoding, on the basis of the low-band decoded signal, a high-band signal having a band higher than that of the low-band signal to generate a high-band encoded signal;
• calculating an energy of the voice or audio input signal for each subband of a plurality of subbands of the voice or audio input signal to obtain a calculated energy for each subband of the plurality of subbands of the voice or audio input signal, quantizing the calculated energy for each subband of the plurality of subbands of the voice or audio input signal to obtain a quantized band energy for each subband of the plurality of subbands of the voice or audio input signal, and outputting the quantized band energy for each subband of the plurality of subbands of the voice or audio input signal;
• and
• multiplexing the quantized band energy for each subband of the plurality of subbands of the voice or audio input signal, the first encoded signal and the high-band encoded signal to generate and output an encoded signal,
• wherein the encoding the high-band signal comprises:
• outputting, as lag information, position information regarding a specific band in which a correlation between the high-band signal and a low-band tonal signal derived from the low-band decoded signal becomes maximum, the lag information being included in the high-band encoded signal.

A decoding method for a first encoded signal, a high-band encoded signal comprising lag information, and a band energy encoded signal representing a quantized band energy for each subband of a plurality of subbands, the method comprising:

• decoding the first encoded signal to generate a low-band decoded signal;
• decoding the high-band encoded signal to generate a wide-band decoded signal by using the low-band decoded signal;
• and
• decoding the band energy encoded signal to generate a quantized band energy for each subband of the plurality of subbands;
• wherein the decoding the high-band encoded signal comprises:
• copying a low-band non-tonal signal derived from the low-band decoded signal to a high band by using the lag information obtained by decoding the high-band encoded signal to obtain a high-band non-tonal signal;
• estimating an energy of a high-band tonal signal from an energy of the high-band non-tonal signal and the quantized band energy for a subband of the plurality of subbands;
• and
• adding the low-band non-tonal signal, the high-band non-tonal signal a low-band tonal signal derived from the low-band decoded signal, and a high-band tonal signal derived from the low-band decoded signal and the lag information to generate a wide-band decoded signal.