Speech decoding device and speech decoding method

摘要

The present invention pertains to a speech decoding device that is capable of preventing degradation in sound quality associated with an adjustment of the slope of a spectrum of an output signal (a decoding signal), making it less likely that a loss of bandwidth sensitivity due to the attenuation of a higher band region is perceived. For each frame of the bandwidth extension layer decoding signal, a filter assessment unit (304) determines whether or not to apply a low-pass filter to the bandwidth extension layer decoding signal on the basis of a change in energy in the bandwidth extension layer decoding signal. A low-pass filtering unit (306) filters the bandwidth extension layer decoding signal of the frames to which the low-pass filter is to be applied, as determined by the filter assessment unit (304), using the low-pass filter.

主权项

1. A speech decoding apparatus, comprising:
a memory that stores instructions; and a processor that executes the instructions, wherein, when executed by the processor, the instructions cause the processor to perform a process comprising: acquiring first layer coded data obtained by encoding a speech signal of a wideband region and band extension layer coded data obtained by encoding a speech signal of an extension band region that is a higher band than the wideband region; decoding the acquired first layer coded data to generate a first layer decoded signal and decoding the acquired band extension layer coded data to generate a band extension layer decoded signal; determining for each frame of the band extension layer decoded signal whether to apply a low-pass filter to the band extension layer decoded signal; performing filter processing on the band extension layer decoded signal of the frame to which the low-pass filter will be applied, and calculating energy of the band extension layer decoded signal for each of the frames of the band extension layer decoded signal, and when a difference between energy of the band extension layer decoded signal of the current frame and average energy of the band extension layer decoded signal up to the current frame is equal to or greater than a threshold, determining that the low-pass filter will be applied to the band extension layer decoded signal of the current frame.