EP0424121A2
Expired / Lapsed
EP
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Speech coding system
Assignee: Toshiba Corp
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Filing: 1990-10-17
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Granted: —
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Expires: 2010-10-17
Abstract
Abstract This invention provides a novel speech coding system which recursively executes filter-applied "Toeplitz characteristic" by causing the "drive signal utilizing to be converted into the "Toeplitz matrix" when detecting such a pitch period in which which distortion of the input vector and the vector subsequent to the application of filter-applied computation to the drive signal vector in the pitch forecast called either "closed loop" or "compatible code book" is minimized. The vector quantamization method substantially making up the speech coding system of the invention characteristically used a by the system.
Inventors
- 👤 Masami C/O Intellectual Property Div. Akamine
- 👤 Yuji C/O Intellectual Property Div. Okuda
- 👤 Kimio C/O Intellectual Property Div. Miseki
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 15:27
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/04; G10L19/08; G10L19/083; G10L19/12; G10L19/16; G10L2019/0001; G10L2019/0011; G10L2019/0013; G10L2019/0014
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
348 words
A speech coding system, comprising: a means (102) which, on receipt of input speech signal, outputs said input speech signal in the form of an input speech vector having one frame of unit; an analyzing means (104) for analyzing said input speech vector by means of a liner predictive coding method and extracting a predictive parameter from said input speech vector; a weighting means (105) for weighting said input speech vector with said predictive parameter from said analyzing means, and for outputing a first weighted input speech vector; a drive signal generating means (118) for generating a filter drive signal for driving a synthesis filter; a drive signal vector generating means (116) for generating a first drive signal vector when a pitch period exceeds a predetermined value, and for generating a second drive signal vector when the pitch period is below the predetermined value, said first and second drive signal vectors being obtained from said drive signal; a computing means (119a) and (120a) for recursively executing operations by using composed of drive signal matrix including said first and-second drive signal vectors as Toeplitz matrix when executing the operations to determine optimal pitch period at which error between said first weighted input speech vector and said drive signal vector is minimum, a first synthetic filter means (109) for generating synthesis speech vector corresponding to said optimal pitch period; a means (131) for externally delivering a second weighted input speech vector obtained by excluding the influence of a last frame and the influence of a pitch from said first weighted input speech vector and said synthetic speech vector; a code vector generating means (117) for generating a code vector available for detecting the content of a code book and expressible by means of said Toeplitz matrix; a second synthetic filter means (114) for computtomg said code vector for filtering; and a selection means (119b) and (120b) for selecting from said code vector generating means an optimal code vector at which the difference between an output from said second synthesis filter means and said second weighted input speech vector is minimized.
Claim 2
Dependent Claim
348 words
A speech coding system, comprising: a means (102) which, on receipt of input speech signal, outputs said input speech signal in the form of an input speech vector having one frame of unit; an analyzing means (104) for analyzing said input speech vector by means of a liner predictive coding method and extracting a predictive parameter from said input speech vector; a weighting means (105) for weighting said input speech vector with said predictive parameter from said analyzing means, and for outputing a first weighted input speech vector; a drive signal generating means (118) for generating a filter drive signal for driving a synthesis filter; a drive signal vector generating means (116) for generating a first drive signal vector when a pitch period exceeds a predetermined value, and for generating a second drive signal vector when the pitch period is below the predetermined value, said first and second drive signal vectors being obtained from said drive signal; a computing means (119a) and (120a) for recursively executing operations by using composed of drive signal matrix including said first and-second drive signal vectors as Toeplitz matrix when executing the operations to determine optimal pitch period at which error between said first weighted input speech vector and said drive signal vector is minimum, a first synthetic filter means (109) for generating synthesis speech vector corresponding to said optimal pitch period; a means (131) for externally delivering a second weighted input speech vector obtained by excluding the influence of a last frame and the influence of a pitch from said first weighted input speech vector and said synthetic speech vector; a code vector generating means (117) for generating a code vector available for detecting the content of a code book and expressible by means of said Toeplitz matrix; a second synthetic filter means (114) for computtomg said code vector for filtering; and a selection means (119b) and (120b) for selecting from said code vector generating means an optimal code vector at which the difference between an output from said second synthesis filter means and said second weighted input speech vector is minimized.
Claim 3
Dependent Claim
107 words
The speech coding system, according to claim 1, characterized in that said drive signal vector generating means (116) and (130) includes: a delay circuit (116), and a waveform coupling means (130) which synthesizes the predetermined speech waveform and those speech waveforms preliminarily stored in a storage means (110) for storing the past speech waveform; and characterized in that said drive signal vector generating means (116) and (130) is connected to a switching means (115) which, in accordance with a predetermined condition, switches the destination of signal delivered from said drive signal generatig means (118) either to said delay circuit (116) or to said waveform coupling means (130).
Claim 4
Dependent Claim
129 words
The speech coding system, according to claim 2, characterized in that, if said pitch period (j) were in excess of the dimensional number (k) of said code vector, said switching means (115) generates signal from said drive signal generating means (118) to said delay circuit (116), whereas if said pitch period (j) were less than the dimensional number (k) of said code vector, said switching means (115) outputs signal from said drive signal generating means (118) to said waveform coupling means (130); characterized in that said delay circuit (116) delays said pitch period to the predetermined level and produces the past drive signal vector (e); and characterized in that said waveform coupling means (130) couples zero-vector with said past drive signal vector (e), and then produces drive signal vector.
Claim 5
Dependent Claim
117 words
The speech coding system, according to claim 1, further comprising a pitch analyzing means (103) which is connected to said ana-lyzing means (104) to execute pitch analysis for implementing long-term speech forecast by applying said forecast parameter {αi} (i = 1, ..., P, where P designates prediction order) extracted from said analyzing means (104) and also applying an forecast residual signal vector designating the difference generating forecast error, and then said pitch analyzing means (103) extracts the pitch period (j) resulted from said pitch analysis and the optimal gain parameter (Y j ) suited for this pitch period, and finally outputs the value of said optimal gain parameter (γ j ) to said waveform coupling means (130).
Claim 6
Dependent Claim
340 words
A speech coding system which encodes speech by means of a drive signal matrix including drive signal vector available for generating synthesis speech and a code-book matrix including code vector, comprising the following steps: a step which designates said drive signal matrix and code-book matrix by means of Toeplitz matrix; the first computation step which, to detect a pitch period at which the error between the input speech vector corresponding to input speech signal and said drive signal vector remains minimum, computes distortion corresponding to squate distance of said error by means of equation (1) shown below; and the second computation step which executes equation (2) shown below to select a specific code vector at which said distortion can remain minimum; characterized in that said first computation step includes a step for executing said equation (1) based on matrix-vector product calculation and recursive calculation using characteristic of Toeplitz matrix; and characterized in that said second computation step includes a step for executing said equation (2) based on matrix-vector functional calculation and recursive calculation using characteristic of Toeplitz matrix; E j = ∥X t - γ j HB j ∥ (20 ≦ j ≦ 147) (1) where X t designates the target vector: B j drive signal vector when the pitch period "j" is present; γ j the optimal gain parameter against the pitch period "j"; (20 ≦ j ≦ 147) designates detectable range of the pitch period "j"; and H designates the value countable by applying the trigonometric determinant shown below, E j = ∥X t - γ j HC j ∥ (1 ≦ j ≦ n) (2) where X t designates the weighted input vector free from the influence of the last frame and the pitch; C j the j-th code vector; γ j the optimal gain parameter against the j-th code vector; n the number of code vectors; and H designates the value countable by applying the trigonometric determinant shown below, where "k" designates the dimensional number of said drive signal vector B j and the code vector.
Claim 7
Dependent Claim
340 words
A speech coding system which encodes speech by means of a drive signal matrix including drive signal vector available for generating synthesis speech and a code-book matrix including code vector, comprising the following steps: a step which designates said drive signal matrix and code-book matrix by means of Toeplitz matrix; the first computation step which, to detect a pitch period at which the error between the input speech vector corresponding to input speech signal and said drive signal vector remains minimum, computes distortion corresponding to squate distance of said error by means of equation (1) shown below; and the second computation step which executes equation (2) shown below to select a specific code vector at which said distortion can remain minimum; characterized in that said first computation step includes a step for executing said equation (1) based on matrix-vector product calculation and recursive calculation using characteristic of Toeplitz matrix; and characterized in that said second computation step includes a step for executing said equation (2) based on matrix-vector functional calculation and recursive calculation using characteristic of Toeplitz matrix; E j = ∥X t - γ j HB j ∥ (20 ≦ j ≦ 147) (1) where X t designates the target vector: B j drive signal vector when the pitch period "j" is present; γ j the optimal gain parameter against the pitch period "j"; (20 ≦ j ≦ 147) designates detectable range of the pitch period "j"; and H designates the value countable by applying the trigonometric determinant shown below, E j = ∥X t - γ j HC j ∥ (1 ≦ j ≦ n) (2) where X t designates the weighted input vector free from the influence of the last frame and the pitch; C j the j-th code vector; γ j the optimal gain parameter against the j-th code vector; n the number of code vectors; and H designates the value countable by applying the trigonometric determinant shown below, where "k" designates the dimensional number of said drive signal vector B j and the code vector.
Claim 8
Dependent Claim
73 words
The speech coding system, according to claim 5, characterized in that said second computation step comprises the following two steps in the speech coding process using vector quantization including: step (S10) for determining the first matrix-vector product (HC₁) of the pitch period by applying a matrix-vector product computation; step (S20) for storing said first matrix-vector product; and characterized in that a computing process (P01) related to the first pitch period is initially executed.
Claim 9
Dependent Claim
133 words
A speech coding system, comprising the method of executing vector quantization for specifying prospective indexes based on the target vector, code vector, and the critical value of gain of the predetermined code vector including sequential steps of: step (21a) for gaining vector power produced based on said prospective indexes; step (21b) for gaining inner product of said vector and the target vector; step (22) for specifying said prospective indexes based on said power, said inner product, and the critical value of the gain of the predetermined code vector; step (23) for detecting and selecting quantized output index by applying said power and inner product based on the specified prospective indexes; and step (24) for quantizing the gain of the code vector using the power and the inner product based on the selected index.
Claim 10
Dependent Claim
133 words
A speech coding system, comprising the method of executing vector quantization for specifying prospective indexes based on the target vector, code vector, and the critical value of gain of the predetermined code vector including sequential steps of: step (21a) for gaining vector power produced based on said prospective indexes; step (21b) for gaining inner product of said vector and the target vector; step (22) for specifying said prospective indexes based on said power, said inner product, and the critical value of the gain of the predetermined code vector; step (23) for detecting and selecting quantized output index by applying said power and inner product based on the specified prospective indexes; and step (24) for quantizing the gain of the code vector using the power and the inner product based on the selected index.
Claim 11
Dependent Claim
107 words
A speech coding system, executing those sequential steps in the speech coding process using vector quantization including: step (21a) for gaining vector power produced based on the prospective index specifying the predetermined vector in the preset code vector table; step (21b) for gaining the inner product of said vector and the target vector; step (22) for specifying the prospective indexes based on said power, said inner product, and the critical value of the gain of the present code vector; and step (13) for detecting and selecting the quantized output index and the acquired gain using said power and said inner product based on the specified prospective indexes.
Claim 12
Dependent Claim
107 words
A speech coding system, executing those sequential steps in the speech coding process using vector quantization including: step (21a) for gaining vector power produced based on the prospective index specifying the predetermined vector in the preset code vector table; step (21b) for gaining the inner product of said vector and the target vector; step (22) for specifying the prospective indexes based on said power, said inner product, and the critical value of the gain of the present code vector; and step (13) for detecting and selecting the quantized output index and the acquired gain using said power and said inner product based on the specified prospective indexes.
Claim 13
Dependent Claim
148 words
A speech coding system, characterized by further comprising: an input means (102) which, on receipt of input speech signal, generates said input speech signal in a form of an input speech vector; a weighting means (105) which weights the input speech vector by means of a predetermined parameter and generates a weighted input speech vector; a drive signal vector generating means (118, 115, 116, 130) which extracts and generates a drive signal vector from a filter drive signal for driving a liner predictive coding check filter; a computing means (119) for recursively executing operations by using a drive signal matrix having the drive signal vector as Toeplitz matrix when executing operations to determine an optimal pitch period at which error between the weighted input speech vector and the drive signal vector is minimum; and generating means (109) for outputting a speech vector corresponding to the optimal pitch period.
Claim 14
Dependent Claim
148 words
A speech coding system, characterized by further comprising: an input means (102) which, on receipt of input speech signal, generates said input speech signal in a form of an input speech vector; a weighting means (105) which weights the input speech vector by means of a predetermined parameter and generates a weighted input speech vector; a drive signal vector generating means (118, 115, 116, 130) which extracts and generates a drive signal vector from a filter drive signal for driving a liner predictive coding check filter; a computing means (119) for recursively executing operations by using a drive signal matrix having the drive signal vector as Toeplitz matrix when executing operations to determine an optimal pitch period at which error between the weighted input speech vector and the drive signal vector is minimum; and generating means (109) for outputting a speech vector corresponding to the optimal pitch period.
Claim 15
Dependent Claim
60 words
The speech coding system, according to claim 9, characterized in that said drive signal vector generating means (116, 130) includes means (116, 130) for generating the drive signal vector including a first drive signal vector generated when a pitch period exceeds a predetermined value and a second drive signal vector produced when the pitch period is below the predetermined value.
Claim 16
Dependent Claim
105 words
A speech coding system, characterized by further comprising: generating means (102) which, on receipt of input speech signal, generates the input speech signal in a form of an input speech vector; a weighting means (105) which weights the input speech vector by means of a predetermined parameter and generates a weights input speech vector; a code vector generating means (117) which generates a code vector available for detecting the content of a code book and expressible by means of a Toeplitz matrix; and means (119) for computing the code vector represented by the Toeplitz matrix to obtain an optimal code vector from said code book.
Claim 17
Dependent Claim
105 words
A speech coding system, characterized by further comprising: generating means (102) which, on receipt of input speech signal, generates the input speech signal in a form of an input speech vector; a weighting means (105) which weights the input speech vector by means of a predetermined parameter and generates a weights input speech vector; a code vector generating means (117) which generates a code vector available for detecting the content of a code book and expressible by means of a Toeplitz matrix; and means (119) for computing the code vector represented by the Toeplitz matrix to obtain an optimal code vector from said code book.
References Cited (Backward Citations)
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