alaw

Functions

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

alaw [ option ] [ infile ]

• -v double

  • absolute maximum value of input $(0<V)$

• -a double

  • compression factor $(1\le A)$

• infile str

  • double-type input data sequence

• stdout

  • double-type compressed data sequence

In the below example, 16-bit data read from data.short is compressed to 8-bit A-law format.

x2x +sd data.short | alaw | quantize > data.alaw

Parameters:

• argc – [in] Number of arguments.

• argv – [in] Argument vector.

Returns:

0 on success, 1 on failure.

See also

ialaw ulaw

class ALawCompression

Nonlinearly compress data based on A-law algorithm.

Given the input data $x(n)$, the compression is performed as follows:

$$\begin{array}{r}y(n)=V\mathrm{sgn}(x(n))\{\begin{array}{ll}\frac{A\frac{|x(n)|}{V}}{1+\log A},& \frac{|x(n)|}{V}<\frac{1}{A}\\ \frac{1+\log (A\frac{|x(n)|}{V})}{1+\log A},& \frac{|x(n)|}{V}\ge \frac{1}{A}\end{array}\end{array}$$

where $V$ is the absolute maximum value of the input data and $A$ is the compression factor, which is typically set to 87.6.

Public Functions

ALawCompression(double abs_max_value, double compression_factor)

Parameters:

• abs_max_value – [in] Absolute maximum value.

• compression_factor – [in] Compression factor, $A$.

inline double GetAbsMaxValue() const

Returns:

Absolute maximum value.

inline double GetCompressionFactor() const

Returns:

Compression factor.

inline bool IsValid() const

Returns:

True if this object is valid.

bool Run(double input, double *output) const

Parameters:

• input – [in] Input data.

• output – [out] Output data.

Returns:

True on success, false on failure.

bool Run(double *input_and_output) const

Parameters:

input_and_output – [inout] Input/output data.

Returns:

True on success, false on failure.