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:

\[\begin{split} y(n) = V \, \mathrm{sgn}(x(n)) \left\{ \begin{array}{ll} \frac{A \frac{|x(n)|}{V}}{1 + \log A}, & \frac{|x(n)|}{V} < \frac{1}{A} \\ \frac{1 + \log(A \frac{|x(n)|}{V})}{1 + \log A}, & \frac{|x(n)|}{V} \ge \frac{1}{A} \end{array} \right. \end{split}\]

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.