Encoding device, decoding device, and method thereof for specifying a band of a great error

A decoding apparatus, comprising:

• a receiver that receives:
• first layer encoded data acquired by performing encoding processing with respect to input transform coefficients;
• second layer encoded data acquired by performing encoding processing with respect to a target frequency band where, in first layer error transform coefficients representing an error between the input transform coefficients and first layer decoded transform coefficients which are acquired by decoding the first layer encoded data, a maximum error is found;
• first position information showing a first band which maximizes the error, in a bandwidth wider than the target frequency band;
• and
• second position information showing the target frequency band in the first band;
• a first layer decoder that decodes the first layer encoded data to generate first layer decoded transform coefficients;
• a second layer decoder that specifies the target frequency band based on the first position information and the second position information and decodes the second layer encoded data to generate first layer decoded error transform coefficients;
• and
• a processor that adds the first layer decoded transform coefficients and the first layer decoded error transform coefficients to generate second layer decoded transform coefficients.

An encoding method performed by a processor, the processor executing operations comprising:

• performing encoding processing with respect to input transform coefficients to generate first layer encoded data;
• performing decoding processing using the first layer encoded data to generate first layer decoded transform coefficients;
• and
• performing encoding processing with respect to a target frequency band where, in first layer error transform coefficients representing an error between the input transform coefficients and the first layer decoded transform coefficients, a maximum error is found, to generate second layer encoded data,
• wherein the encoding processing with respect to the target frequency band comprises:
• searching for a first band comprising the maximum error throughout a full band, based on a wider bandwidth than the target frequency band and a predetermined first step size to generate first position information showing the specified first band;
• searching for the target frequency band throughout the first band, based on a narrower second step size than the predetermined first step size to generate second position information showing the target frequency band;
• and
• encoding the first layer error transform coefficients included in the target frequency band specified based on the first position information and the second position information to generate encoded information.

A decoding method performed by a processor, the processor executing operations comprising:

• receiving:
• first layer encoded data acquired by performing encoding processing with respect to input transform coefficients;
• second layer encoded data acquired by performing encoding processing with respect to a target frequency band where, in first layer error transform coefficients representing an error between the input transform coefficients and first layer decoded transform coefficients which are acquired by decoding the first layer encoded data, a maximum error is found;
• first position information showing a first band which maximizes the error, in a bandwidth wider than the target frequency band;
• and
• second position information showing the target frequency band in the first band;
• decoding the first layer encoded data to generate first layer decoded transform coefficients;
• specifying the target frequency band based on the first position information and the second position information and decoding the second layer encoded data to generate first layer decoded error transform coefficients;
• and
• adding the first layer decoded transform coefficients and the first layer decoded error transform coefficients to generate second layer decoded transform coefficients.