Voice coding device, voice decoding device, voice coding method and voice decoding method

摘要

A voice coding device capable of preventing overall quality degradation even when the bit rate for coding is lowered. The voice coding device codes a wide band signal in a first layer, and codes an extended band signal whose frequency band is located in higher frequency than the wide band signal in an extended band layer. An adaptive band selection unit (301) selects a frequency band to be excluded from a coding object in the extended band layer or a frequency band whose energy is to be attenuated in the extended band layer. A band-limited signal generation unit (302) excludes, within the frequency band of an input signal, the frequency band selected by the adaptive band selection unit (301) from the coding object, or attenuates the energy of the frequency band selected by the adaptive band selection unit (301).

主权项

1. A speech encoding apparatus configured to encode a wide band signal of an input speech signal in a first layer and to encode an extended band signal of the input speech signal, whose frequency band is located in higher frequency than the wide band signal, in an extended band layer, the apparatus comprising:
a band-selector that selects, as a frequency band to which a limiting is applied, a frequency band to be removed from an encoding target in the extended band layer when encoding is performed in the extended band layer; and a band-limiter that applies the limiting to the selected frequency band of the input speech signal by removing the selected frequency band from the encoding target, wherein: the band-selector selects the frequency band to be removed in correlation with a pitch frequency of the input speech signal, such that the higher the pitch frequency of the input speech signal the wider the frequency band to be removed; each of the band-selector and the band-limiter is included in at least one processor, and the input speech signal is encoded by the at least one processor in accordance with the selecting by the band-selector and the limiting by the band-limiter.