SPEECH ENCODING APPARATUS AND SPEECH ENCODING METHOD
First Claim
1. A speech encoding apparatus comprising:
- a linear prediction analyzing section that performs a linear prediction analysis with respect to a speech signal to generate a linear prediction coefficient;
a quantizing section that quantizes the linear prediction coefficient;
a perceptual weighting section that performs perceptual weighting filtering with respect to an input speech signal to generate a perceptual weighted speech signal using a transfer function including a tilt compensation coefficient for adjusting a spectral slope of a quantization noise;
a tilt compensation coefficient control section that controls the tilt compensation coefficient using a signal to noise ratio of the speech signal in a first frequency band; and
an excitation search section that performs an excitation search of an adaptive codebook and fixed codebook to generate an excitation signal using the perceptual weighted speech signal.
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Accused Products
Abstract
Disclosed is an audio encoding device capable of adjusting a spectrum inclination of a quantized noise without changing the Formant weight. The device includes: an HPF (131) which extracts a high-frequency component of the frequency region from an input audio signal; a high-frequency energy level calculation unit (132) which calculates an energy level of the high-frequency component in a frame unit; an LPF (133) which extracts a low-frequency component of the frequency region from the input audio signal; a low-energy level calculation unit (134) which calculates an energy level of a low-frequency component in a frame unit; an inclination correction coefficient calculation unit (141) multiplies the difference between SNR of the high-frequency component and SNR of the low-frequency component inputted from an adder (140) by a constant and adds a bias component to the product so as to calculate an inclination correction coefficient ?3. The inclination correction coefficient is used for adjusting the spectrum inclination of a quantized noise.
90 Citations
15 Claims
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1. A speech encoding apparatus comprising:
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a linear prediction analyzing section that performs a linear prediction analysis with respect to a speech signal to generate a linear prediction coefficient; a quantizing section that quantizes the linear prediction coefficient; a perceptual weighting section that performs perceptual weighting filtering with respect to an input speech signal to generate a perceptual weighted speech signal using a transfer function including a tilt compensation coefficient for adjusting a spectral slope of a quantization noise; a tilt compensation coefficient control section that controls the tilt compensation coefficient using a signal to noise ratio of the speech signal in a first frequency band; and an excitation search section that performs an excitation search of an adaptive codebook and fixed codebook to generate an excitation signal using the perceptual weighted speech signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A speech encoding method comprising the steps of:
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performing a linear prediction analysis with respect to a speech signal to generate a linear prediction coefficient; quantizing the linear prediction coefficient; performing perceptual weighting filtering with respect to an input speech signal to generate a perceptual weighted speech signal using a transfer function including a tilt compensation coefficient for adjusting a spectral slope of a quantization noise; controlling the tilt compensation coefficient using a signal to noise ratio in a first frequency band of the speech signal; and performing an excitation search of an adaptive codebook and fixed codebook to generate an excitation signal using the perceptual weighted speech signal. - View Dependent Claims (15)
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Specification