SPEECH SIGNAL DECODING DEVICE AND METHOD FOR DECODING SPEECH SIGNAL

• US 20180182407A1
• Filed: 05/20/2016
• Published: 06/28/2018
• Est. Priority Date: 08/05/2015
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: EHARA, Hiroyuki
• Granted Patent: US 10,347,266 B2
• Time in Patent Office: Days
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/08 Determination or coding of the excitation function; Determination or coding of the long-term prediction parameters
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• CPC Class Codes: G10L 19/125 Pitch excitation, e.g. pitch synchronous innovation CELP [PSI-CELP]
• CPC Class Codes: G10L 19/16 Vocoder architecture
• CPC Class Codes: G10L 21/003 Changing voice quality, e.g. pitch or formants
• CPC Class Codes: G10L 25/90 Pitch determination of speech signals
• CPC Class Codes: H03M 7/30 Compression speech analysis-synthesis for redundancy reduction G10L19/00; for image communication H04N; Expansion; Suppression of unnecessary data, e.g. redundancy reduction

Abstract

A speech signal decoding device includes an adaptive code-book decoder, a fixed code-book decoder, a ratio calculator, a determination unit, and an attenuator. The adaptive code-book decoder generates an adaptive code-book vector using an adaptive code-book code of an encoded signal encoded by a CELP method. The fixed code-book decoder generates a fixed code-book vector using a fixed code-book code of the encoded signal. The ratio calculator calculates an amplitude ratio or an energy ratio between the adaptive code-book vector and the fixed code-book vector. The determination unit determines whether the amplitude ratio or the energy ratio exceeds a predetermined threshold. When the amplitude ratio or the energy ratio is determined to exceed the predetermined threshold, the attenuator attenuates an excitation signal that has been defined by adding the adaptive code-book vector to the fixed code-book vector.

Claims

1. A speech signal decoding device comprising:

an adaptive code-book decoder that generates an adaptive code-book decoded component using an adaptive code-book code of an encoded signal encoded by a code-excited linear prediction (CELP) method;

a fixed code-book decoder that generates a fixed code-book decoded component using a fixed code-book code of the encoded signal;

a ratio calculator that calculates an amplitude ratio or an energy ratio between the adaptive code-book decoded component and the fixed code-book decoded component;

a determination unit that determines whether the amplitude ratio or the energy ratio, which has been calculated by the ratio calculator, exceeds a predetermined threshold; and

an attenuator that attenuates an excitation signal that has been defined by adding the adaptive code-book decoded component to the fixed code-book decoded component, when the determination unit determines that the amplitude ratio or the energy ratio exceeds the predetermined threshold.

2. The speech signal decoding device according to claim 1, further comprising a demultiplexer that separates the encoded signal into the adaptive code-book code and the fixed code-book code for each frame.

3. The speech signal decoding device according to claim 2, wherein, when a frame whose amplitude ratio or energy ratio is determined to exceed the predetermined threshold by the determination unit is present, the attenuator attenuates excitation signals of a predetermined number of frames subsequent to the determined frame.

4. The speech signal decoding device according to claim 1, further comprising a synthesis filter that generates a decoded speech signal from the excitation signal attenuated by the attenuator.

5. A method for decoding a speech signal comprising:

generating an adaptive code-book decoded component using an adaptive code-book code of an encoded signal encoded by a code-excited linear prediction (CELP) method;

generating a fixed code-book decoded component using a fixed code-book code of the encoded signal;

calculating an amplitude ratio or an energy ratio between the adaptive code-book decoded component and the fixed code-book decoded component;

determining whether the amplitude ratio or the energy ratio exceeds a predetermined threshold; and

attenuating an excitation signal that has been defined by adding the adaptive code-book decoded component to the fixed code-book decoded component, when the amplitude ratio or the energy ratio is determined to exceed the predetermined threshold.