Dither.cpp File Reference

#include "Dither.h"
#include "Internat.h"
#include "Prefs.h"
#include "float_cast.h"
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <wx/defs.h>

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Classes
struct	State

Typedefs
using	Ditherer = float(*)(State &, float)

Functions
static float	DITHER_NOISE ()
static float	FROM_INT16 (const short *ptr)
static float	FROM_INT24 (const int *ptr)
static float	FROM_FLOAT (const float *ptr)
template<typename dst_type >
static void	IMPLEMENT_STORE (dst_type *ptr, float sample, dst_type min_bound, dst_type max_bound)
static void	DITHER_TO_INT16 (Ditherer dither, State &state, short *dst, float sample)
static void	DITHER_TO_INT24 (Ditherer dither, State &state, int *dst, float sample)
template<typename srcType , typename dstType >
static void	DITHER_LOOP (Ditherer dither, State &state, void(*store)(Ditherer, State &, dstType *, float), float(*load)(const srcType *), samplePtr dst, sampleFormat dstFormat, size_t dstStride, constSamplePtr src, sampleFormat srcFormat, size_t srcStride, size_t len)
static void	DITHER (Ditherer dither, State &state, samplePtr dst, sampleFormat dstFormat, size_t dstStride, constSamplePtr src, sampleFormat srcFormat, size_t srcStride, size_t len)
static float	NoDither (State &, float sample)
static float	RectangleDither (State &, float sample)
static float	TriangleDither (State &state, float sample)
static float	ShapedDither (State &state, float sample)

Variables
constexpr int	BUF_SIZE = 8
constexpr int	BUF_MASK = 7
const float	SHAPED_BS [] = { 2.033f, -2.165f, 1.959f, -1.590f, 0.6149f }
struct State	mState
constexpr auto	CONVERT_DIV16 = float(1<<15)
constexpr auto	CONVERT_DIV24 = float(1<<23)
static const std::initializer_list< EnumValueSymbol >	choicesDither
static auto	intChoicesDither

Typedef Documentation

Ditherer

using Ditherer = float (*)(State &, float)

Definition at line 73 of file Dither.cpp.

Function Documentation

DITHER()

static void DITHER ( Ditherer  dither, State &  state, samplePtr  dst, sampleFormat  dstFormat, size_t  dstStride, constSamplePtr  src, sampleFormat  srcFormat, size_t  srcStride, size_t  len  )

inlinestatic

Definition at line 162 of file Dither.cpp.

{
    if (srcFormat == int24Sample && dstFormat == int16Sample)
        DITHER_LOOP<int, short>(dither, state,
            DITHER_TO_INT16, FROM_INT24, dst,
            int16Sample, dstStride, src, int24Sample, srcStride, len);
    else if (srcFormat == floatSample && dstFormat == int16Sample)
        DITHER_LOOP<float, short>(dither, state,
            DITHER_TO_INT16, FROM_FLOAT, dst,
            int16Sample, dstStride, src, floatSample, srcStride, len);
    else if (srcFormat == floatSample && dstFormat == int24Sample)
        DITHER_LOOP<float, int>(dither, state,
            DITHER_TO_INT24, FROM_FLOAT, dst,
            int24Sample, dstStride, src, floatSample, srcStride, len);
    else { wxASSERT(false); }
}

References DITHER_TO_INT16(), DITHER_TO_INT24(), floatSample, FROM_FLOAT(), FROM_INT24(), int16Sample, and int24Sample.

Referenced by Dither::Apply().

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DITHER_LOOP()

template<typename srcType , typename dstType >

static void DITHER_LOOP ( Ditherer  dither, State &  state, void(*)(Ditherer, State &, dstType *, float)  store, float(*)(const srcType *)  load, samplePtr  dst, sampleFormat  dstFormat, size_t  dstStride, constSamplePtr  src, sampleFormat  srcFormat, size_t  srcStride, size_t  len  )

inlinestatic

Definition at line 143 of file Dither.cpp.

{
    char *d;
    const char *s;
    unsigned int ii;
    for (d = (char*)dst, s = (char*)src, ii = 0;
        ii < len;
        ii++, d += SAMPLE_SIZE(dstFormat) * dstStride,
        s += SAMPLE_SIZE(srcFormat) * srcStride) {
            store(dither, state, reinterpret_cast<dstType *>(d), load(reinterpret_cast<const srcType *>(s)));
        }
}

References SAMPLE_SIZE.

DITHER_NOISE()

static float DITHER_NOISE ( )

inlinestatic

Definition at line 76 of file Dither.cpp.

{
    return rand() / (float)RAND_MAX - 0.5f;
}

Referenced by RectangleDither(), ShapedDither(), and TriangleDither().

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DITHER_TO_INT16()

static void DITHER_TO_INT16 ( Ditherer  dither, State &  state, short *  dst, float  sample  )

inlinestatic

Definition at line 123 of file Dither.cpp.

{
    IMPLEMENT_STORE<short>(dst,
        dither(state, sample * CONVERT_DIV16),
        short(-32768), short(32767));
}

References CONVERT_DIV16.

Referenced by DITHER().

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DITHER_TO_INT24()

static void DITHER_TO_INT24 ( Ditherer  dither, State &  state, int *  dst, float  sample  )

inlinestatic

Definition at line 132 of file Dither.cpp.

{
    IMPLEMENT_STORE<int>(dst,
        dither(state, sample * CONVERT_DIV24), -8388608, 8388607);
}

References CONVERT_DIV24.

Referenced by DITHER().

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FROM_FLOAT()

static float FROM_FLOAT ( const float *  ptr )

inlinestatic

Definition at line 99 of file Dither.cpp.

{
    return *((float*)(ptr)) > 1.0
        ?  1.0 :
        *((float*)(ptr)) < -1.0
            ? -1.0 :
            *((float*)(ptr));
}

Referenced by DITHER().

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FROM_INT16()

static float FROM_INT16 ( const short *  ptr )

inlinestatic

Definition at line 86 of file Dither.cpp.

{
    return *ptr / CONVERT_DIV16;
}

References CONVERT_DIV16.

Referenced by Dither::Apply().

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FROM_INT24()

static float FROM_INT24 ( const int *  ptr )

inlinestatic

Definition at line 91 of file Dither.cpp.

{
    return *ptr / CONVERT_DIV24;
}

References CONVERT_DIV24.

Referenced by Dither::Apply(), and DITHER().

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IMPLEMENT_STORE()

template<typename dst_type >

static void IMPLEMENT_STORE ( dst_type *  ptr, float  sample, dst_type  min_bound, dst_type  max_bound  )

inlinestatic

Definition at line 110 of file Dither.cpp.

{
    int x = lrintf(sample);
    if (x > max_bound)
        *ptr = max_bound;
    else if (x<(min_bound))
        *ptr = min_bound;
    else
        *ptr = static_cast<dst_type>(x);
}

References lrintf.

NoDither()

float NoDither ( State &  , float  sample  )

inlinestatic

Definition at line 331 of file Dither.cpp.

{
    return sample;
}

Referenced by Dither::Apply().

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RectangleDither()

float RectangleDither ( State &  , float  sample  )

inlinestatic

Definition at line 337 of file Dither.cpp.

{
    return sample - DITHER_NOISE();
}

References DITHER_NOISE().

Referenced by Dither::Apply().

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ShapedDither()

float ShapedDither ( State &  state, float  sample  )

inlinestatic

Definition at line 353 of file Dither.cpp.

{
    // Generate triangular dither, +-1 LSB, flat psd
    float r = DITHER_NOISE() + DITHER_NOISE();
    if(sample != sample)  // test for NaN
       sample = 0; // and do the best we can with it
 
    // Run FIR
    float xe = sample + state.mBuffer[state.mPhase] * SHAPED_BS[0]
        + state.mBuffer[(state.mPhase - 1) & BUF_MASK] * SHAPED_BS[1]
        + state.mBuffer[(state.mPhase - 2) & BUF_MASK] * SHAPED_BS[2]
        + state.mBuffer[(state.mPhase - 3) & BUF_MASK] * SHAPED_BS[3]
        + state.mBuffer[(state.mPhase - 4) & BUF_MASK] * SHAPED_BS[4];
 
    // Accumulate FIR and triangular noise
    float result = xe + r;
 
    // Roll buffer and store last error
    state.mPhase = (state.mPhase + 1) & BUF_MASK;
    state.mBuffer[state.mPhase] = xe - lrintf(result);
 
    return result;
}

References BUF_MASK, DITHER_NOISE(), lrintf, State::mBuffer, State::mPhase, and SHAPED_BS.

Referenced by Dither::Apply().

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TriangleDither()

float TriangleDither ( State &  state, float  sample  )

inlinestatic

Definition at line 343 of file Dither.cpp.

{
    float r = DITHER_NOISE();
    float result = sample + r - state.mTriangleState;
    state.mTriangleState = r;
 
    return result;
}

References DITHER_NOISE(), and State::mTriangleState.

Referenced by Dither::Apply().

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Variable Documentation

BUF_MASK

constexpr int BUF_MASK = 7

constexpr

Definition at line 61 of file Dither.cpp.

Referenced by ShapedDither().

BUF_SIZE

constexpr int BUF_SIZE = 8

constexpr

Definition at line 60 of file Dither.cpp.

Referenced by Dither::Reset().

choicesDither

const std::initializer_list<EnumValueSymbol> choicesDither

static

Initial value:

{
   { XO("None") },
   { XO("Rectangle") },
   { XC("Triangle", "dither") },
   { XO("Shaped") },
}

Definition at line 377 of file Dither.cpp.

CONVERT_DIV16

constexpr auto CONVERT_DIV16 = float(1<<15)

constexpr

Definition at line 82 of file Dither.cpp.

Referenced by DITHER_TO_INT16(), and FROM_INT16().

CONVERT_DIV24

constexpr auto CONVERT_DIV24 = float(1<<23)

constexpr

Definition at line 83 of file Dither.cpp.

Referenced by DITHER_TO_INT24(), and FROM_INT24().

intChoicesDither

auto intChoicesDither

static

Initial value:

= {
   DitherType::none,
   DitherType::rectangle,
   DitherType::triangle,
   DitherType::shaped,
}

Definition at line 383 of file Dither.cpp.

mState

struct State mState

Referenced by Dither::Apply(), audacity::cloud::audiocom::sync::CloudSyncStatusField::GetWidth(), audacity::cloud::audiocom::sync::RemoteProjectSnapshot::InProgress(), audacity::cloud::audiocom::sync::CloudSyncStatusField::IsVisible(), audacity::cloud::audiocom::sync::CloudSyncStatusField::MarkDirty(), audacity::cloud::audiocom::sync::CloudSyncStatusField::OnCloudStatusChanged(), EffectBassTreble::Instance::ProcessBlock(), EffectPhaser::Instance::ProcessBlock(), EffectReverb::Instance::ProcessBlock(), EffectWahwah::Instance::ProcessBlock(), EffectBassTreble::Instance::ProcessInitialize(), EffectPhaser::Instance::ProcessInitialize(), EffectReverb::Instance::ProcessInitialize(), EffectWahwah::Instance::ProcessInitialize(), EffectBassTreble::Instance::RealtimeProcess(), EffectPhaser::Instance::RealtimeProcess(), EffectWahwah::Instance::RealtimeProcess(), audacity::cloud::audiocom::sync::RemoteProjectSnapshot::ReportProgress(), Dither::Reset(), audacity::cloud::audiocom::sync::RemoteProjectSnapshot::SetState(), and ToolBarGrabber::ToolBarGrabber().

SHAPED_BS

const float SHAPED_BS[] = { 2.033f, -2.165f, 1.959f, -1.590f, 0.6149f }

Definition at line 64 of file Dither.cpp.

Referenced by ShapedDither().