dct

Functions

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

dct [ option ] [ infile ]

• -l int

  • DCT length $(1\le L)$

• -q int

  • input format

    • 0 real and imaginary parts

    • 1 real part

• -o int

  • output format

    • 0 real and imaginary parts

    • 1 real part

    • 2 imaginary part

    • 3 amplitude spectrum

    • 4 power spectrum

• infile str

  • double-type data sequence

• stdout

  • double-type DCT sequence

Parameters:

• argc – [in] Number of arguments.

• argv – [in] Argument vector.

Returns:

0 on success, 1 on failure.

See also

idct

class DiscreteCosineTransform

Calculate DCT-II of complex-valued input data.

The inputs are $L$-length order complex-valued data:

$$\begin{array}{r}\begin{array}{cccc}\mathrm{Re}(x(0)),& \mathrm{Re}(x(1)),& \dots ,& \mathrm{Re}(x(L-1)),\\ \mathrm{Im}(x(0)),& \mathrm{Im}(x(1)),& \dots ,& \mathrm{Im}(x(L-1)).\end{array}\end{array}$$

The outputs are

$$\begin{array}{r}\begin{array}{cccc}\mathrm{Re}(X(0)),& \mathrm{Re}(X(1)),& \dots ,& \mathrm{Re}(X(L-1)),\\ \mathrm{Im}(X(0)),& \mathrm{Im}(X(1)),& \dots ,& \mathrm{Im}(X(L-1)).\end{array}\end{array}$$

They are computed as

$$X(k)=\sqrt{\frac{2}{L}}c(k)\sum _{n=0}^{L-1}x(n)\cos \left(\frac{\pi }{L}(n+\frac{1}{2})k\right),$$

where

$$\begin{array}{r}c(k)=\{\begin{array}{ll}1/\sqrt{2},& k=0\\ 1.& 1\le k<L\end{array}\end{array}$$

Public Functions

explicit DiscreteCosineTransform(int dct_length)

Parameters:

dct_length – [in] DCT length, $L$.

inline int GetDctLength() const

Returns:

DCT length.

inline bool IsValid() const

Returns:

True if this object is valid.

bool Run(const std::vector<double> &real_part_input, const std::vector<double> &imag_part_input, std::vector<double> *real_part_output, std::vector<double> *imag_part_output, DiscreteCosineTransform::Buffer *buffer) const

Parameters:

• real_part_input – [in] $L$-length real part of input.

• imag_part_input – [in] $L$-length imaginary part of input.

• real_part_output – [out] $L$-length real part of output.

• imag_part_output – [out] $L$-length imaginary part of output.

• buffer – [out] Buffer.

Returns:

True on success, false on failure.

bool Run(std::vector<double> *real_part, std::vector<double> *imag_part, DiscreteCosineTransform::Buffer *buffer) const

Parameters:

• real_part – [inout] $L$-length real part.

• imag_part – [inout] $L$-length imaginary part.

• buffer – [out] Buffer.

Returns:

True on success, false on failure.

class Buffer

Buffer for DiscreteCosineTransform class.