mc2b
Functions
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int main(int argc, char *argv[])
mc2b [ option ] [ infile ]
-m int
order of coefficients \((0 \le M)\)
-a double
all-pass constant \((|\alpha| < 1)\)
infile str
double-type mel-cepstral coefficients
stdout
double-type MLSA digital filter coefficients
The below example converts mel-cepstral coefficients into MLSA digital filter coefficients:
mc2b < data.mc > data.b
The converted MLSA digital filter coefficients can be reverted by
b2mc < data.b > data.mc
- Parameters
argc – [in] Number of arguments.
argv – [in] Argument vector.
- Returns
0 on success, 1 on failure.
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class sptk::MelCepstrumToMlsaDigitalFilterCoefficients
Convert mel-cepstral coefficients to MLSA digital filter coefficients.
The input is the \(M\)-th order mel-cepstral coefficients:
\[ \begin{array}{cccc} \tilde{c}(0), & \tilde{c}(1), & \ldots, & \tilde{c}(M), \end{array} \]and the output is the \(M\)-th order MLSA digital filter coefficients:\[ \begin{array}{cccc} b(0), & b(1), & \ldots, & b(M). \end{array} \]The MLSA digital filter coefficients can be obtained by the linear transformation of the mel-cepstral coefficients:\[ \boldsymbol{b} = \boldsymbol{A}^{-1}\tilde{\boldsymbol{c}}, \]where\[\begin{split}\begin{eqnarray} \boldsymbol{A}^{-1} &=& \left[ \begin{array}{ccccc} 1 & -\alpha & (-\alpha)^2 & \cdots & (-\alpha)^M \\ 0 & 1 & -\alpha & \ddots & \vdots \\ 0 & 0 & 1 & \ddots & (-\alpha)^2 \\ \vdots & \vdots & \ddots & \ddots & -\alpha \\ 0 & 0 & \cdots & 0 & 1 \\ \end{array} \right], \\ \boldsymbol{b} &=& \left[ \begin{array}{cccc} b(0) & b(1) & \cdots & b(M) \end{array} \right]^{\mathsf{T}}, \\ \tilde{\boldsymbol{c}} &=& \left[ \begin{array}{cccc} \tilde{c}(0) & \tilde{c}(1) & \cdots & \tilde{c}(M) \end{array} \right]^{\mathsf{T}}. \end{eqnarray}\end{split}\]The conversion is implemented with low computational complexity in a recursive manner as follows:\[\begin{split} b(m) = \left\{ \begin{array}{ll} \tilde{c}(m), & m = M \\ \tilde{c}(m) - \alpha b(m + 1). & 0 \le m < M \end{array} \right. \end{split}\][1] K. Tokuda, T. Kobayashi, T. Chiba, and S. Imai, “Spectral estimation of speech by mel-generalized cepstral analysis,” Electronics and Communications in Japan, part 3, vol. 76, no. 2, pp. 30-43, 1993.
Public Functions
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MelCepstrumToMlsaDigitalFilterCoefficients(int num_order, double alpha)
- Parameters
num_order – [in] Order of coefficients, \(M\).
alpha – [in] Frequency warping factor, \(\alpha\).
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inline int GetNumOrder() const
- Returns
Order of coefficients.
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inline double GetAlpha() const
- Returns
Frequency warping factor.
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inline bool IsValid() const
- Returns
True if this object is valid.
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bool Run(const std::vector<double> &mel_cepstrum, std::vector<double> *mlsa_digital_filter_coefficients) const
- Parameters
mel_cepstrum – [in] \(M\)-th order mel-cepstral coefficients.
mlsa_digital_filter_coefficients – [out] \(M\)-th order MLSA digital filter coefficients.
- Returns
True on success, false on failure.
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bool Run(std::vector<double> *input_and_output) const
- Parameters
input_and_output – [inout] \(M\)-th order coefficients.
- Returns
True on success, false on failure.
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MelCepstrumToMlsaDigitalFilterCoefficients(int num_order, double alpha)