CS-ACELP speech compression system with adaptive pitch prediction filter gain based on a measure of periodicity
DCFirst Claim
1. A method for use in a speech processing system which includes a first portion comprising an adaptive codebook and corresponding adaptive codebook amplifier and a second portion comprising a fixed codebook coupled to a pitch filter, the pitch filter comprising a delay memory coupled to a pitch filter amplifier, the method comprising:
- determining the pitch filter gain based on a measure of periodicity of a speech signal; and
amplifying samples of a signal in said pitch filter based on said determined pitch filter gain.
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Abstract
A speech coding system employing an adaptive codebook model of periodicity is augmented with a pitch-predictive filter (PPF). This PPF has a delay equal to the integer component of the pitch-period and a gain which is adaptive based on a measure of periodicity of the speech signal. In accordance with an embodiment of the present invention, speech processing systems which include a first portion comprising an adaptive codebook and corresponding adaptive codebook amplifier and a second portion comprising a fixed codebook coupled to a pitch filter, are adapted to delay the adaptive codebook gain; determine the pitch filter gain based on the delayed adaptive codebook gain, and amplify samples of a signal in the pitch filter based on said determined pitch filter gain. The adaptive codebook gain is delayed for one subframe. The pitch filter gain equals the delayed. adaptive codebook gain, except when the adaptive codebook gain is either less than 0.2 or greater than 0.8., in which cases the pitch filter gain is set equal to 0.2 or 0.8, respectively.
405 Citations
19 Claims
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1. A method for use in a speech processing system which includes a first portion comprising an adaptive codebook and corresponding adaptive codebook amplifier and a second portion comprising a fixed codebook coupled to a pitch filter, the pitch filter comprising a delay memory coupled to a pitch filter amplifier, the method comprising:
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determining the pitch filter gain based on a measure of periodicity of a speech signal; and amplifying samples of a signal in said pitch filter based on said determined pitch filter gain. - View Dependent Claims (2, 3, 4, 5, 6, 16)
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7. A speech processing system comprising:
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a first portion including an adaptive codebook and means for applying an adaptive codebook gain, and a second portion including a fixed codebook, a pitch filter, wherein the pitch filter includes a means for applying a pitch filter gain, and wherein the improvement comprises; means for determining said pitch filter gain, based on a measure of periodicity of a speech signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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17. A method for determining a gain of a pitch filter for use in a speech processing system, the system including a first portion comprising an adaptive codebook and corresponding adaptive codebook amplifier and a second portion comprising a fixed codebook coupled to a pitch filter, the pitch filter comprising a delay memory coupled to a pitch filter amplifier for applying said determined gain, the speech processing system for processing a speech signal, the method comprising:
determining the pitch filter gain based on periodicity of the speech signal.
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18. A method for use in a speech processing system which includes a first portion which comprises an adaptive codebook and corresponding adaptive codebook amplifier and a second portion which comprises a fixed codebook coupled to a pitch filter, the pitch filter. comprising a delay memory coupled to a pitch filter amplifier, the method comprising:
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delaying the adaptive codebook gain; determining the pitch filter gain to be equal to the delayed adaptive codebook gain, except when the adaptive codebook gain is either less than 0.2 or greater than 0.8., in which cases the pitch filter gain is set equal to 0.2 or 0.8, respectively; and amplifying samples of a signal in said pitch filter based on said determined pitch filter gain.
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19. A speech processing system comprising:
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a first portion including an adaptive codebook and means for applying an adaptive codebook gain, and a second portion including a fixed codebook, a pitch filter, means for applying a second gain, wherein the pitch filter includes a means for applying a pitch filter gain, and wherein the improvement comprises; means for determining said pitch filter gain, said means for determining including means for setting the pitch filter gain equal to an adaptive codebook gain, said signal gain is either less than 0.2 or greater than 0.8., in which cases-the pitch filter gain is set equal to 0.2 or 0.8, respectively.
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Specification