lspdf

Functions

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

lspdf [ option ] wfile [ infile ]

-m int
- order of coefficients \((0 \le M)\)
-p int
- frame period \((1 \le P)\)
-i int
- interpolation period \((0 \le I \le P/2)\)
-k int
- input gain type
  - 0 linear gain
  - 1 log gain
  - 2 unity gain
wfile str
- double-type LSP coefficients
infile str
- double-type input sequence
stdout
- double-type output sequence

In the below example, an excitation signal generated from pitch information is passed through the synthesis filter built from LSP coefficients.

excite < data.pitch | lspdf data.lsp > data.syn

Parameters:

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

Returns:

0 on success, 1 on failure.

See also

lpc2lsp lspcheck

class LineSpectralPairsDigitalFilter

Apply line spectral pairs (LSP) digital filter to signals.

The transfer function \(H(z)\) of LSP filter is

\[ H(z) = \displaystyle\frac{K}{1 + \frac{P(z) - 1 + Q(z) - 1}{2}}, \]

where

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

Given the \(M\)-th order filter coefficients,

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

an output signal is obtained by applying \(H(z)\) to an input signal in time domain.

[1] N. Sugamura and F. Itakura, “Speech data compression by LSP speech analysis-synthesis technique,” Journal of IEICE, vol. J64-A, no. 8, pp. 599-606, 1981.

Public Functions

explicit LineSpectralPairsDigitalFilter(int num_filter_order)

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

inline int GetNumFilterOrder() const

Returns:: Order of coefficients.

inline bool IsValid() const

Returns:: True if this object is valid.

bool Run(const std::vector<double> &filter_coefficients, double filter_input, double *filter_output, LineSpectralPairsDigitalFilter::Buffer *buffer) const

Parameters:

filter_coefficients – [in] \(M\)-th order LSP filter coefficients.
filter_input – [in] Input signal.
filter_output – [out] Output signal.
buffer – [inout] Buffer.

Returns:

True on success, false on failure.

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

Parameters:

filter_coefficients – [in] \(M\)-th order LSP filter coefficients.
input_and_output – [inout] Input/output signal.
buffer – [inout] Buffer.

Returns:

True on success, false on failure.

class Buffer: Buffer for LineSpectralPairsDigitalFilter class.