lpc2c
Functions
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int main(int argc, char *argv[])
lpc2c [ option ] [ infile ]
-m int
order of LPC coefficients \((0 \le M_1)\)
-M int
order of LPC cepstral coefficients \((0 \le M_2)\)
infile str
double-type LPC coefficients
stdout
double-type LPC cepstral coefficients
The below example extracts 15-th order LPC cepstral coefficients from
data.d.frame < data.d | window | lpc -m 10 | lpc2c -m 10 -M 15 > data.cep
- Parameters
argc – [in] Number of arguments.
argv – [in] Argument vector.
- Returns
0 on success, 1 on failure.
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class sptk::LinearPredictiveCoefficientsToCepstrum
Convert LPC coefficients to LPC cepstral coefficients.
The input is the \(M_1\)-th order LPC coefficients:
\[ \begin{array}{cccc} K, & a(1), & \ldots, & a(M_1), \end{array} \]and the output is the \(M_2\)-th order cepstral coefficients:\[ \begin{array}{cccc} c(0), & c(1), & \ldots, & c(M_2). \end{array} \]The cesptral coefficients is obtained by the following recursion:\[\begin{split} c(m) = \left\{ \begin{array}{ll} \log K, & m = 0 \\ -a(m) - \displaystyle\sum_{k=1}^{m-1} \frac{k}{m} c(k) a(m-k), & (0 < m \le M_1) \\ -\displaystyle\sum_{k=m-M_1}^{m-1} \frac{k}{m} c(k) a(m-k). & (M_1 < m \le M_2) \end{array} \right. \end{split}\]This simple recursion does not require any DFTs.Public Functions
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LinearPredictiveCoefficientsToCepstrum(int num_input_order, int num_output_order)
- Parameters
num_input_order – [in] Order of LPC coefficients, \(M_1\).
num_output_order – [in] Order of cepstral coefficients, \(M_2\).
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inline int GetNumInputOrder() const
- Returns
Order of LPC coefficients.
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inline int GetNumOutputOrder() const
- Returns
Order of cepstral coefficients.
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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> &linear_predictive_coefficients, std::vector<double> *cepstrum) const
- Parameters
linear_predictive_coefficients – [in] \(M_1\)-th order LPC coefficients.
cepstrum – [out] \(M_2\)-th order cepstral coefficients.
- Returns
True on success, false on failure.
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LinearPredictiveCoefficientsToCepstrum(int num_input_order, int num_output_order)