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 exciation 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.