Functions for generating dither noise. More...

#include "pa_types.h"
#include "pa_dither.h"

Macros
#define	PA_DITHER_BITS_ (15)

#define	DITHER_SHIFT_ ((sizeof(PaInt32)*8 - PA_DITHER_BITS_) + 1)

#define	PA_FLOAT_DITHER_SCALE_ (1.0f / ((1<<PA_DITHER_BITS_)-1))

Functions
void	PaUtil_InitializeTriangularDitherState (PaUtilTriangularDitherGenerator *state)
	Initialize dither state.

PaInt32	PaUtil_Generate16BitTriangularDither (PaUtilTriangularDitherGenerator *state)
	Calculate 2 LSB dither signal with a triangular distribution. Ranged for adding to a 1 bit right-shifted 32 bit integer prior to >>15. eg:

float	PaUtil_GenerateFloatTriangularDither (PaUtilTriangularDitherGenerator *state)
	Calculate 2 LSB dither signal with a triangular distribution. Ranged for adding to a pre-scaled float.

Detailed Description

Functions for generating dither noise.

Macro Definition Documentation

◆ DITHER_SHIFT_

#define DITHER_SHIFT_ ((sizeof(PaInt32)*8 - PA_DITHER_BITS_) + 1)

Referenced by PaUtil_Generate16BitTriangularDither(), and PaUtil_GenerateFloatTriangularDither().

◆ PA_DITHER_BITS_

#define PA_DITHER_BITS_ (15)

◆ PA_FLOAT_DITHER_SCALE_

#define PA_FLOAT_DITHER_SCALE_ (1.0f / ((1<<PA_DITHER_BITS_)-1))

Function Documentation

◆ PaUtil_Generate16BitTriangularDither()

PaInt32 PaUtil_Generate16BitTriangularDither ( PaUtilTriangularDitherGenerator * ditherState )

Calculate 2 LSB dither signal with a triangular distribution. Ranged for adding to a 1 bit right-shifted 32 bit integer prior to >>15. eg:

    signed long in = *
    signed long dither = PaUtil_Generate16BitTriangularDither( ditherState );
    signed short out = (signed short)(((in>>1) + dither) >> 15);

Returns: A signed 32-bit integer with a range of +32767 to -32768

References DITHER_SHIFT_, PaUtilTriangularDitherGenerator::previous, PaUtilTriangularDitherGenerator::randSeed1, and PaUtilTriangularDitherGenerator::randSeed2.

Referenced by ShowDitherDistribution().

◆ PaUtil_GenerateFloatTriangularDither()

float PaUtil_GenerateFloatTriangularDither ( PaUtilTriangularDitherGenerator * ditherState )

Calculate 2 LSB dither signal with a triangular distribution. Ranged for adding to a pre-scaled float.

    float in = *
    float dither = PaUtil_GenerateFloatTriangularDither( ditherState );
    // use smaller scaler to prevent overflow when we add the dither
    signed short out = (signed short)(in*(32766.0f) + dither );

Returns: A float with a range of -2.0 to +1.99999.

References DITHER_SHIFT_, PaUtilTriangularDitherGenerator::previous, PaUtilTriangularDitherGenerator::randSeed1, and PaUtilTriangularDitherGenerator::randSeed2.

◆ PaUtil_InitializeTriangularDitherState()

void PaUtil_InitializeTriangularDitherState ( PaUtilTriangularDitherGenerator * state )

Initialize dither state.

References PaUtilTriangularDitherGenerator::previous, PaUtilTriangularDitherGenerator::randSeed1, and PaUtilTriangularDitherGenerator::randSeed2.

Referenced by main(), PaUtil_InitializeBufferProcessor(), and ShowDitherDistribution().

Macros

Functions