Patent ID: 8756068
Filing Date: 2014-06-17
Classification: G10L

Abstract:
1. A speech decoder that decodes a coded sequence of encoded speech signal, comprising: a demultiplexing unit for demultiplexing the coded sequence into a low frequency band coded sequence and a high frequency band coded sequence; a low frequency band decoding unit for decoding the low frequency band coded sequence demultiplexed by the demultiplexing unit and obtaining a low frequency band signal; a frequency transformation unit for transforming the low frequency band signal, which is obtained by the low frequency band decoding unit, into a frequency domain; a high frequency band coded sequence analysis unit for analyzing the high frequency band coded sequence demultiplexed by the demultiplexing unit and acquiring supplementary information for high frequency band generation and time envelope information; a coded sequence decoding and dequantization unit for decoding and inversely quantizing the supplementary information for high frequency band generation and the time envelope information acquired by the high frequency band coded sequence analysis unit; a high frequency band generation unit for generating, using the supplementary information for high frequency band generation decoded by the coded sequence decoding and dequantization unit, high frequency band components in the speech signal from the low frequency band signal transformed into the frequency domain by the frequency transformation unit; a first to Nth (N is an integer equal to or larger than two) low frequency band time envelope calculation unit for analyzing the low frequency band signal transformed into the frequency domain by the frequency transformation unit and acquiring time envelopes for a plurality of low frequency bands; a time envelope calculation unit for calculating a high frequency band time envelope using the time envelope information, which is acquired by the coded sequence decoding and dequantization unit, and the plurality of low frequency band time envelopes, which are acquired by the low frequency band time envelope calculation unit; a time envelope adjustment unit for adjusting, using the time envelope acquired by the time envelope calculation unit, a time envelope of the high frequency band components generated by the high frequency band generation unit; and a signal outputting unit for adding the high frequency band components, which are adjusted by the time envelope adjustment unit, and the low frequency band signal, which is decoded by the low frequency band decoding unit, and outputting a time domain signal containing entire frequency band components.