Decoding device, encoding device, decoding method, and encoding method

An encoding device for encoding an original signal, comprising:

• a processor;
• and
• a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute,
• outputting main signal code obtained by encoding low-frequency components of the original signal, and auxiliary information code obtained by encoding auxiliary information for generating a highband main signal corresponding to high-frequency components of the original signal, from a lowband main signal obtained by decoding the main signal code;
• and
• outputting residual code obtained by encoding low-frequency components of a residual signal indicating error components produced by encoding of the original signal,
• the auxiliary information with the high-frequency components of the original signal usable to generate a highband residual signal from a lowband residual signal from the residual code.

A decoding method to decode a main signal code obtained by encoding low-frequency components of an original signal, the method comprising:

• decoding the main signal code obtained by the encoding low-frequency components of the original signal, and thereby outputting a lowband main signal;
• decoding auxiliary information code obtained by encoding auxiliary information for generating a highband main signal corresponding to high-frequency components of the original signal, from the lowband main signal, and thereby outputting the auxiliary information;
• decoding residual code obtained by encoding low-frequency components of a residual signal indicating error components produced by encoding of the original signal, and thereby output a lowband residual signal;
• generating, by a processor, the highband main signal based on the lowband main signal outputted by the outputting of the lowband main signal and the auxiliary information outputted by the outputting of the auxiliary information;
• generating a highband residual signal indicating high-frequency components of the residual signal, based on the lowband residual signal output by the outputting of the lowband residual signal and the auxiliary information outputted by the outputting of the auxiliary information;
• generating an output signal based on the lowband main signal, the highband main signal, the lowband residual signal and the highband residual signal.