mc2b

Functions

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.

See also

b2mc mgc2mgc

class sptk::MelCepstrumToMlsaDigitalFilterCoefficients

Convert mel-cepstral coefficients to MLSA digital filter coefficients.

The input is the $M$-th order mel-cepstral coefficients:

$$\begin{array}{cccc}\tilde{c}(0),& \tilde{c}(1),& \dots ,& \tilde{c}(M),\end{array}$$

and the output is the $M$-th order MLSA digital filter coefficients:

$$\begin{array}{cccc}b(0),& b(1),& \dots ,& b(M).\end{array}$$

The MLSA digital filter coefficients can be obtained by the linear transformation of the mel-cepstral coefficients:

$$\mathit{b}={\mathit{A}}^{-1}\tilde{\mathit{c}},$$

where

$$\begin{array}{r}\begin{array}{rcl}{\mathit{A}}^{-1}& =& \left[\begin{array}{ccccc}1& -\alpha & (-\alpha {)}^2& \cdots & (-\alpha {)}^M\\ 0& 1& -\alpha & \ddots & ⋮\\ 0& 0& 1& \ddots & (-\alpha {)}^2\\ ⋮& ⋮& \ddots & \ddots & -\alpha \\ 0& 0& \cdots & 0& 1\end{array}\right],\\ \mathit{b}& =& {\left[\begin{array}{cccc}b(0)& b(1)& \cdots & b(M)\end{array}\right]}^{\mathsf{T}},\\ \tilde{\mathit{c}}& =& {\left[\begin{array}{cccc}\tilde{c}(0)& \tilde{c}(1)& \cdots & \tilde{c}(M)\end{array}\right]}^{\mathsf{T}}.\end{array}\end{array}$$

The conversion is implemented with low computational complexity in a recursive manner as follows:

$$\begin{array}{r}b(m)=\{\begin{array}{ll}\tilde{c}(m),& m=M\\ \tilde{c}(m)-\alpha b(m+1).& 0\le m<M\end{array}\end{array}$$

[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

MelCepstrumToMlsaDigitalFilterCoefficients(int num_order, double alpha)

Parameters

• num_order – [in] Order of coefficients, $M$.

• alpha – [in] Frequency warping factor, $\alpha$.

inline int GetNumOrder() const

Returns

Order of coefficients.

inline double GetAlpha() const

Returns

Frequency warping factor.

inline bool IsValid() const

Returns

True if this object is valid.

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.

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.