lsp2lpc

Functions

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

lsp2lpc [ option ] [ infile ]

-m int
- order of coefficients \((0 \le M)\)
-s double
- sampling rate \((0 < F_s)\)
-k int
- input gain type
  - 0 linear gain
  - 1 log gain
  - 2 without gain
-q int
- input format
  - 0 frequency in rad
  - 1 frequency in cyc
  - 2 frequency in kHz
  - 3 frequency in Hz
infile str
- double-type LSP coefficients
stdout
- double-type LPC coefficients

Parameters:

argc – [in] Number of arguments.
argv – [in] Argument vector.

Returns:

0 on success, 1 on failure.

See also

lpc2lsp

class LineSpectralPairsToLinearPredictiveCoefficients

Convert line spectral pairs to linear predictive coefficients.

The input is the \(M\)-th order LSP:

\[ \begin{array}{cccc} K, & \omega(1), & \ldots, & \omega(M), \end{array} \]

and the output is the \(M\)-th order LPC:

\[ \begin{array}{cccc} K, & a(1), & \ldots, & a(M). \end{array} \]

The LSP coefficients are the roots of the following polynomials:

\[\begin{split}\begin{eqnarray} P(z)&=&(1-z^{-1})\prod_{m=2,4,\ldots}^M (1-2\cos\omega(m)z^{-1}+z^{-2}), \\ Q(z)&=&(1+z^{-1})\prod_{m=1,3,\ldots}^M (1-2\cos\omega(m)z^{-1}+z^{-2}). \end{eqnarray}\end{split}\]

The relation between the polynomials and the all-pole filter is

\[\begin{split}\begin{eqnarray} A(z) &=& 1 + \sum_{m=1}^M a(m) z^{-m} \\ &=& \displaystyle\frac{P(z) + Q(z)}{2}. \end{eqnarray}\end{split}\]

The LPC coefficients are derived from the LSP coefficients using the above relation.

Public Functions

explicit LineSpectralPairsToLinearPredictiveCoefficients(int num_order)

Parameters:: num_order – [in] Order of coefficients, \(M\).

inline int GetNumOrder() const

Returns:: Order of coefficients.

inline bool IsValid() const

Returns:: True if this object is valid.

bool Run(const std::vector<double> &line_spectral_pairs, std::vector<double> *linear_predictive_coefficients, LineSpectralPairsToLinearPredictiveCoefficients::Buffer *buffer) const

Parameters:

line_spectral_pairs – [in] \(M\)-th order LSP.
linear_predictive_coefficients – [out] \(M\)-th order LPC.
buffer – [out] Buffer.

Returns:

True on success, false on failure.

bool Run(std::vector<double> *input_and_output, LineSpectralPairsToLinearPredictiveCoefficients::Buffer *buffer) const

Parameters:

input_and_output – [inout] \(M\)-th order coefficients.
buffer – [out] Buffer.

Returns:

True on success, false on failure.

class Buffer: Buffer for LineSpectralPairsToLinearPredictiveCoefficients class.