smcep

Functions

int main(int argc, char *argv[])

smcep [ option ] [ infile ]

• -m int

  • order of coefficients \((0 \le M)\)

• -a double

  • all-pass constant \((|\alpha| < 1)\)

• -t double

  • emphasized frequency in \(\pi\) rad \((0 \le \theta \le 1.0)\)

• -l int

  • FFT length \((2 \le N)\)

• -q int

  • input format

    • 0 amplitude spectrum in dB

    • 1 log amplitude spectrum

    • 2 amplitude spectrum

    • 3 power spectrum

    • 4 windowed waveform

• -f int

  • accuracy factor \((1 \le F)\)

• -i int

  • number of iterations \((0 \le J)\)

• -d double

  • convergence threshold \((0 \le \epsilon)\)

• -e double

  • small value added to power spectrum

• -E double

  • relative floor in decibels

• infile str

  • double-type windowed sequence or spectrum

• stdout

  • double-type mel-cepstral coefficients

In the example below, mel-cepstral coefficients are extracted from data.d.

frame < data.d | window | smcep -t 0.12 > data.mcep

Parameters

• argc – [in] Number of arguments.

• argv – [in] Argument vector.

Returns

0 on success, 1 on failure.

See also

mgcep

class sptk::SecondOrderAllPassMelCepstralAnalysis

Calculate mel-cepstrum from periodogram.

The input is the half of periodogram:

\[ \begin{array}{cccc} |X(0)|^2, & |X(1)|^2, & \ldots, & |X(N/2)|^2, \end{array} \]

where \(N\) is the FFT length. The output is the \(M\)-th order mel-cepstral coefficients:

\[ \begin{array}{cccc} \tilde{c}(0), & \tilde{c}(1), & \ldots, & \tilde{c}(M). \end{array} \]

In the mel-cepstral analysis based on the second order all-pass function, the spectrum of speech signal is modeled by \(M\)-th order mel-cepstral coefficients as follows:

\[ H(z) = \exp \sum_{m=0}^M \tilde{c}(m) \displaystyle\frac{A^m(z) + A^m(z^{-1})}{2}, \]

where

\[ A(z) = \left( \frac{z^{-2} - 2\alpha\cos\theta z^{-1} + \alpha^2} {1 - 2\alpha \cos\theta z^{-1} + \alpha^2 z^{-2}} \right)^{1/2}. \]

The phase characteristic of the all-pass function is controlled by the two parameters: \(\alpha\) and \(\theta\).

Note that the implemenation is based on an unpublished paper.

Public Functions

SecondOrderAllPassMelCepstralAnalysis(int fft_length, int num_order, int accuracy_factor, double alpha, double theta, int num_iteration, double convergence_threshold)

Parameters

• fft_length – [in] Number of FFT bins, \(N\).

• num_order – [in] Order of cepstral coefficients, \(M\).

• accuracy_factor – [in] Accuracy of frequency transform. This must be a power of two.

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

• theta – [in] Frequency emphasis factor, \(\theta\).

• num_iteration – [in] Number of iterations of Newton method, \(J\).

• convergence_threshold – [in] Convergence threshold, \(\epsilon\).

inline int GetFftLength() const

Returns

FFT length.

inline int GetNumOrder() const

Returns

Order of coefficients.

inline double GetAlpha() const

Returns

All-pass constant.

inline double GetTheta() const

Returns

Frequency emphasis factor.

inline int AccuracyFactor() const

Returns

A factor for making a conversion matrix of frequency transform.

inline int GetNumIteration() const

Returns

Number of iterations.

inline double GetConvergenceThreshold() const

Returns

Convergence threshold.

inline bool IsValid() const

Returns

True if this object is valid.

bool Run(const std::vector<double> &periodogram, std::vector<double> *mel_cepstrum, SecondOrderAllPassMelCepstralAnalysis::Buffer *buffer) const

Parameters

• periodogram – [in] \((N/2+1)\)-length periodogram.

• mel_cepstrum – [out] \(M\)-th order mel-cepstral coefficients.

• buffer – [out] Buffer.

Returns

True on success, false on failure.

class Buffer

Buffer for SecondOrderAllPassMelCepstralAnalysis class.

class sptk::SecondOrderAllPassFrequencyTransform

Transform a minimum phase sequence into a frequency-warped sequence.

Public Functions

SecondOrderAllPassFrequencyTransform(int num_input_order, int num_output_order, int fft_length, double alpha, double theta)

Parameters

• num_input_order – [in] Order of input, \(M_1\).

• num_output_order – [in] Order of output, \(M_2\).

• fft_length – [in] FFT length used to make conversion matrix.

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

• theta – [in] Frequency emphasis factor, \(\theta\).

inline int GetNumInputOrder() const

Returns

Order of input.

inline int GetNumOutputOrder() const

Returns

Order of output.

inline double GetAlpha() const

Returns

Frequency warping factor.

inline double GetTheta() const

Returns

Frequency emphasis factor.

inline bool IsValid() const

Returns

True if this object is valid.

bool Run(const std::vector<double> &minimum_phase_sequence, std::vector<double> *warped_sequence) const

Parameters

• minimum_phase_sequence – [in] \(M_1\)-th order input sequence.

• warped_sequence – [out] \(M_2\)-th order output sequence.

Returns

True on success, false on failure.

class sptk::SecondOrderAllPassInverseFrequencyTransform

Transform a frequency-warped sequence into a minimum phase sequence.

Public Functions

SecondOrderAllPassInverseFrequencyTransform(int num_input_order, int num_output_order, int fft_length, double alpha, double theta)

Parameters

• num_input_order – [in] Order of input, \(M_1\).

• num_output_order – [in] Order of output, \(M_2\).

• fft_length – [in] FFT length used to make conversion matrix.

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

• theta – [in] Frequency emphasis factor, \(\theta\).

inline int GetNumInputOrder() const

Returns

Order of input.

inline int GetNumOutputOrder() const

Returns

Order of output.

inline double GetAlpha() const

Returns

Frequency warping factor.

inline double GetTheta() const

Returns

Frequency emphasis factor.

inline bool IsValid() const

Returns

True if this object is valid.

bool Run(const std::vector<double> &warped_sequence, std::vector<double> *minimum_phase_sequence) const

Parameters

• warped_sequence – [in] \(M_1\)-th order input sequence.

• minimum_phase_sequence – [out] \(M_2\)-th order output sequence.

Returns

True on success, false on failure.