Files
UnrealEngine/Engine/Source/Runtime/SignalProcessing/Private/SpectrumAnalyzer.cpp
2025-05-18 13:04:45 +08:00

1357 lines
37 KiB
C++

// Copyright Epic Games, Inc. All Rights Reserved.
#include "DSP/SpectrumAnalyzer.h"
#include "Algo/MaxElement.h"
#include "Algo/MinElement.h"
#include "DSP/ConstantQ.h"
#include "DSP/FFTAlgorithm.h"
#include "DSP/FloatArrayMath.h"
#include "SignalProcessingModule.h"
namespace Audio
{
namespace SpectrumAnalyzerIntrinsics
{
// Bit mask for returning even numbers of int32
const int32 EvenNumberMask = 0xFFFFFFFE;
// Constant useful for calculating log10
const float Loge10 = FMath::Loge(10.f);
}
// Implementation of spectrum band extractor
class FSpectrumBandExtractor : public ISpectrumBandExtractor
{
using FBandSettings = ISpectrumBandExtractor::FBandSettings;
// FBandSpec describes specifications for a single band.
struct FBandSpec : public FBandSettings
{
// Location in output array where band value should be stored.
int32 OutIndex;
// The scaling parameter to apply to the power spectrum.
float PowerSpectrumScale;
FBandSpec(const FBandSettings& InBandSettings, const FSpectrumBandExtractorSettings& InSettings, const FSpectrumBandExtractorSpectrumSettings& InSpectrumSettings, int32 InOutIndex)
: FBandSettings(InBandSettings)
, OutIndex(InOutIndex)
, PowerSpectrumScale(1.f)
{
FBandSpec::Update(InSettings, InSpectrumSettings);
}
virtual ~FBandSpec() {}
// Update calculates parameters that are specific to FFT implementation
// and sample rate.
virtual void Update(const FSpectrumBandExtractorSettings& InSettings, const FSpectrumBandExtractorSpectrumSettings& InSpectrumSettings)
{
PowerSpectrumScale = 1.f;
float FloatFFTSize = FMath::Max(static_cast<float>(InSpectrumSettings.FFTSize), 1.f);
switch (InSpectrumSettings.FFTScaling)
{
case EFFTScaling::MultipliedByFFTSize:
PowerSpectrumScale = 1.f / (FloatFFTSize * FloatFFTSize);
break;
case EFFTScaling::MultipliedBySqrtFFTSize:
PowerSpectrumScale = 1.f / FloatFFTSize;
break;
case EFFTScaling::DividedByFFTSize:
PowerSpectrumScale = FloatFFTSize * FloatFFTSize;
break;
case EFFTScaling::DividedBySqrtFFTSize:
PowerSpectrumScale = FloatFFTSize;
break;
case EFFTScaling::None:
default:
PowerSpectrumScale = 1.f;
break;
}
}
void UpdateOutputFromPowerSpectrum(const float* InputBuffer, int32 InNum, float* OutputBuffer, int32 OutNum) const
{
check(OutIndex >= 0);
check(OutIndex < OutNum);
OutputBuffer[OutIndex] = ExtractFromPowerSpectrum(InputBuffer, InNum) * PowerSpectrumScale;
}
virtual float ExtractFromPowerSpectrum(const float* InputBuffer, int32 InNum) const = 0;
};
// Specification for a nearest neighbor band.
struct FNNBandSpec : public FBandSpec
{
// Use parent constructor
using FBandSpec::FBandSpec;
// Index in power spectrum to lookup band.
int32 Index;
virtual void Update(const FSpectrumBandExtractorSettings& InSettings, const FSpectrumBandExtractorSpectrumSettings& InSpectrumSettings) override
{
// Call parent class update.
FBandSpec::Update(InSettings, InSpectrumSettings);
// Update the index
const int32 MaxSpectrumIndex = InSpectrumSettings.FFTSize / 2;
const float Position = CenterFrequency / FMath::Max(InSpectrumSettings.SampleRate, 1.f) * InSpectrumSettings.FFTSize;
Index = FMath::RoundToInt(Position);
Index = FMath::Clamp(Index, 0, MaxSpectrumIndex);
}
virtual float ExtractFromPowerSpectrum(const float* InputBuffer, int32 InNum) const override
{
int32 SafeIndex = FMath::Clamp(Index, 0, InNum);
return InputBuffer[SafeIndex];
}
};
// Specification for a linearly interpolated band.
struct FLerpBandSpec : public FBandSpec
{
// Use parent constructor
using FBandSpec::FBandSpec;
// Lower index power spectrum.
int32 LowerIndex;
// Upper index of power spectrum.
int32 UpperIndex;
// Value used for lerping between lower and upper band values.
float Alpha;
virtual void Update(const FSpectrumBandExtractorSettings& InSettings, const FSpectrumBandExtractorSpectrumSettings& InSpectrumSettings) override
{
// Call parent class update.
FBandSpec::Update(InSettings, InSpectrumSettings);
// Update lower index, upper index and alpha.
const int32 MaxSpectrumIndex = InSpectrumSettings.FFTSize / 2;
const float Position = CenterFrequency / FMath::Max(InSpectrumSettings.SampleRate, 1.f) * InSpectrumSettings.FFTSize;
LowerIndex = FMath::FloorToInt(Position);
UpperIndex = LowerIndex + 1;
Alpha = Position - LowerIndex;
LowerIndex = FMath::Clamp(LowerIndex, 0, MaxSpectrumIndex);
UpperIndex = FMath::Clamp(UpperIndex, 0, MaxSpectrumIndex);
Alpha = FMath::Clamp(Alpha, 0.f, 1.f);
}
virtual float ExtractFromPowerSpectrum(const float* InputBuffer, int32 InNum) const override
{
int32 SafeLowerIndex = FMath::Clamp(LowerIndex, 0, InNum);
int32 SafeUpperIndex = FMath::Clamp(UpperIndex, 0, InNum);
return FMath::Lerp<float>(InputBuffer[SafeLowerIndex], InputBuffer[SafeUpperIndex], Alpha);
}
};
// Specification for band using quadratic interpolation.
struct FQuadraticBandSpec : public FBandSpec
{
// Use parent constructor
using FBandSpec::FBandSpec;
// Lower index of power spectrum used for interpolation.
int32 LowerIndex;
// Middle index of power spectrum used for interpolation.
int32 MidIndex;
// Upper index of power spectrum used for interpolation.
int32 UpperIndex;
// Weight for lower value.
float LowerWeight;
// Weight for middle value.
float MidWeight;
// Weight for upper value.
float UpperWeight;
virtual void Update(const FSpectrumBandExtractorSettings& InSettings, const FSpectrumBandExtractorSpectrumSettings& InSpectrumSettings) override
{
// Call parent class update.
FBandSpec::Update(InSettings, InSpectrumSettings);
QFactor = FMath::Clamp(QFactor, 0.0001f, 10000.f);
// Update indices and weights.
const int32 MaxSpectrumIndex = InSpectrumSettings.FFTSize / 2;
const float Position = CenterFrequency / FMath::Max(InSpectrumSettings.SampleRate, 1.f) * InSpectrumSettings.FFTSize;
MidIndex = FMath::RoundToInt(Position);
LowerIndex = MidIndex - 1;
UpperIndex = MidIndex + 1;
// Calculate polynomail weights
float RelativePosition = Position - LowerIndex;
LowerWeight = ((RelativePosition - 1.f) * (RelativePosition - 2.f)) / 2.f;
MidWeight = (RelativePosition * (RelativePosition - 2.f)) / -1.f;
UpperWeight = (RelativePosition * (RelativePosition - 1.f)) / 2.f;
LowerIndex = FMath::Clamp(LowerIndex, 0, MaxSpectrumIndex);
MidIndex = FMath::Clamp(MidIndex, 0, MaxSpectrumIndex);
UpperIndex = FMath::Clamp(UpperIndex, 0, MaxSpectrumIndex);
}
virtual float ExtractFromPowerSpectrum(const float* InputBuffer, int32 InNum) const override
{
int32 SafeLowerIndex = FMath::Clamp(LowerIndex, 0, InNum);
int32 SafeMidIndex = FMath::Clamp(MidIndex, 0, InNum);
int32 SafeUpperIndex = FMath::Clamp(UpperIndex, 0, InNum);
const float LowerValue = InputBuffer[SafeLowerIndex];
const float MidValue = InputBuffer[SafeMidIndex];
const float UpperValue = InputBuffer[SafeUpperIndex];
return (LowerValue * LowerWeight) + (MidValue * MidWeight) + (UpperValue * UpperWeight);
}
};
// Specification for band using CQT band.
struct FCQTBandSpec : public FBandSpec
{
// Use parent constructor
using FBandSpec::FBandSpec;
// Start index in power spectrum
int32 StartIndex;
// Weights (offset by start index) to apply to power spectrum
FAlignedFloatBuffer Weights;
// Internal buffer used when calculating band.
mutable FAlignedFloatBuffer WorkBuffer;
virtual void Update(const FSpectrumBandExtractorSettings& InSettings, const FSpectrumBandExtractorSpectrumSettings& InSpectrumSettings) override
{
// Call parent class update.
FBandSpec::Update(InSettings, InSpectrumSettings);
// Update band weights and offset index.
const int32 MaxSpectrumIndex = InSpectrumSettings.FFTSize / 2;
const float Position = CenterFrequency / FMath::Max(InSpectrumSettings.SampleRate, 1.f) * InSpectrumSettings.FFTSize;
FPseudoConstantQBandSettings CQTBandSettings;
CQTBandSettings.CenterFreq = CenterFrequency;
CQTBandSettings.BandWidth = FMath::Max(SMALL_NUMBER, CenterFrequency / FMath::Max(SMALL_NUMBER, QFactor));
CQTBandSettings.FFTSize = InSpectrumSettings.FFTSize;
CQTBandSettings.SampleRate = FMath::Max(1.f, InSpectrumSettings.SampleRate);
CQTBandSettings.Normalization = EPseudoConstantQNormalization::EqualEnergy;
StartIndex = 0;
Weights.Reset();
WorkBuffer.Reset();
FPseudoConstantQ::FillArrayWithConstantQBand(CQTBandSettings, Weights, StartIndex);
if (Weights.Num() > 0)
{
WorkBuffer.AddUninitialized(Weights.Num());
}
}
virtual float ExtractFromPowerSpectrum(const float* InputBuffer, int32 InNum) const override
{
int32 SafeStartIndex = FMath::Clamp(StartIndex, 0, InNum);
if (ensure((SafeStartIndex + Weights.Num()) <= InNum))
{
float Value = 0.f;
int32 NumWeights = Weights.Num();
if (NumWeights > 0)
{
check(NumWeights == WorkBuffer.Num());
FMemory::Memcpy(WorkBuffer.GetData(), &InputBuffer[SafeStartIndex], NumWeights * sizeof(float));
ArrayMultiplyInPlace(Weights, WorkBuffer);
ArraySum(WorkBuffer, Value);
}
return Value;
}
return 0.f;
}
};
// Tracks minimum/maximum values given an attack/release time.
class FAutoRange
{
float CurrentMinimum;
float CurrentMaximum;
float AttackTimeConstant;
float ReleaseTimeConstant;
bool bAreCurrentValuesValid;
public:
FAutoRange(float InAttackTime = 0.5f, float InReleaseTime = 30.f)
: CurrentMinimum(0.f)
, CurrentMaximum(0.f)
, AttackTimeConstant(1.f)
, ReleaseTimeConstant(1.f)
, bAreCurrentValuesValid(false)
{
SetAttackTime(InAttackTime);
SetReleaseTime(InReleaseTime);
}
void Set(float InMinimum, float InMaximum)
{
CurrentMinimum = InMinimum;
CurrentMaximum = InMaximum;
bAreCurrentValuesValid = true;
}
void Update(float InMinimumValue, float InMaximumValue, float InTimeDelta)
{
if (bAreCurrentValuesValid)
{
InTimeDelta = FMath::Max(0.f, InTimeDelta);
// The time delta isn't constant between updates, so we need to determine
// how much the value will change.
const float AttackCoef = InTimeDelta * AttackTimeConstant;
const float ReleaseCoef = InTimeDelta * ReleaseTimeConstant;
const float MaxDiff = InMaximumValue - CurrentMaximum;
if (MaxDiff > 0.f)
{
CurrentMaximum += MaxDiff * AttackCoef;
}
else
{
CurrentMaximum += MaxDiff * ReleaseCoef;
}
const float MinDiff = InMinimumValue - CurrentMinimum;
if (MinDiff < 0.f)
{
CurrentMinimum += MinDiff * AttackCoef;
}
else
{
CurrentMinimum += MinDiff * ReleaseCoef;
}
}
else
{
// On first time around, initialize to given min/max values.
Set(InMinimumValue, InMaximumValue);
}
}
// Normalize input values to the min/max range.
void Normalize(TArrayView<float> InValues) const
{
ArrayClampInPlace(InValues, CurrentMinimum, CurrentMaximum);
ArraySubtractByConstantInPlace(InValues, CurrentMinimum);
float Range = FMath::Max(SMALL_NUMBER, CurrentMaximum - CurrentMinimum);
ArrayMultiplyByConstantInPlace(InValues, 1.f / Range);
}
void SetAttackTime(float InAttackTime)
{
// Factor set to achieve 90% of value by attack time.
AttackTimeConstant = 0.9f / FMath::Max(0.001f, InAttackTime);
}
void SetReleaseTime(float InReleaseTime)
{
// Factor set to achieve 90% of value by release time.
ReleaseTimeConstant = 0.9f / FMath::Max(0.001f, InReleaseTime);
}
};
public:
FSpectrumBandExtractor(const FSpectrumBandExtractorSettings& InSettings)
: Settings(InSettings)
, LastTimestamp(0)
{
AutoRange.SetAttackTime(Settings.AutoRangeAttackTimeInSeconds);
AutoRange.SetReleaseTime(Settings.AutoRangeReleaseTimeInSeconds);
}
virtual void SetSettings(const FSpectrumBandExtractorSettings& InSettings) override
{
Settings = InSettings;
AutoRange.SetAttackTime(Settings.AutoRangeAttackTimeInSeconds);
AutoRange.SetReleaseTime(Settings.AutoRangeReleaseTimeInSeconds);
}
virtual void SetSpectrumSettings(const FSpectrumBandExtractorSpectrumSettings& InSpectrumSettings) override
{
bool bSpectrumSettingsChanged = (SpectrumSettings != InSpectrumSettings);
SpectrumSettings = InSpectrumSettings;
if (bSpectrumSettingsChanged)
{
// If the settings have changed from the previous call, the band specs
// need to be updated with the new information.
UpdateBandSpecs();
}
}
// Clear out all added bands.
virtual void RemoveAllBands() override
{
NNBandSpecs.Reset();
LerpBandSpecs.Reset();
QuadraticBandSpecs.Reset();
CQTBandSpecs.Reset();
}
// Return total number of bands.
virtual int32 GetNumBands() const override
{
int32 Num = NNBandSpecs.Num();
Num += LerpBandSpecs.Num();
Num += QuadraticBandSpecs.Num();
Num += CQTBandSpecs.Num();
return Num;
}
virtual void AddBand(const FBandSettings& InBandSettings) override
{
switch (InBandSettings.Type)
{
case EBandType::NearestNeighbor:
AddBand<FNNBandSpec>(NNBandSpecs, InBandSettings);
break;
case EBandType::Lerp:
AddBand<FLerpBandSpec>(LerpBandSpecs, InBandSettings);
break;
case EBandType::Quadratic:
AddBand<FQuadraticBandSpec>(QuadraticBandSpecs, InBandSettings);
break;
case EBandType::ConstantQ:
default:
AddBand<FCQTBandSpec>(CQTBandSpecs, InBandSettings);
break;
}
}
// Extract band from input.
virtual void ExtractBands(const FAlignedFloatBuffer& InComplexBuffer, double InTimestamp, TArray<float>& OutValues) override
{
const int32 NumComplex = InComplexBuffer.Num();
float TimeDelta = FMath::Max(0.0f, static_cast<float>(InTimestamp - LastTimestamp));
LastTimestamp = InTimestamp;
check(NumComplex == (SpectrumSettings.FFTSize + 2));
OutValues.Reset();
OutValues.AddZeroed(GetNumBands());
PowerSpectrum.Reset();
if (NumComplex > 1)
{
PowerSpectrum.AddUninitialized(NumComplex / 2);
}
// All band extractors expect a power spectrum
ArrayComplexToPower(InComplexBuffer, PowerSpectrum);
ExtractBands(PowerSpectrum, NNBandSpecs, OutValues);
ExtractBands(PowerSpectrum, LerpBandSpecs, OutValues);
ExtractBands(PowerSpectrum, QuadraticBandSpecs, OutValues);
ExtractBands(PowerSpectrum, CQTBandSpecs, OutValues);
ApplyMetric(OutValues);
if (Settings.bDoAutoRange)
{
Normalize(OutValues);
float* MinimumValuePtr = Algo::MinElement(OutValues);
float* MaximumValuePtr = Algo::MaxElement(OutValues);
float MinimumValue = MinimumValuePtr == nullptr ? 0.f : *MinimumValuePtr;
float MaximumValue = MaximumValuePtr == nullptr ? 0.f : *MaximumValuePtr;
AutoRange.Update(MinimumValue, MaximumValue, TimeDelta);
AutoRange.Normalize(OutValues);
}
else if (Settings.bDoNormalize)
{
Normalize(OutValues);
ArrayClampInPlace(OutValues, 0.f, 1.f);
}
}
private:
// Adds a band spec and returns a reference to the added spec.
template<typename T>
T& AddBand(TArray<T>& InBandSpecs, const FBandSettings& InBandSettings)
{
int32 OutIndex = GetNumBands();
T BandSpec(InBandSettings, Settings, SpectrumSettings, OutIndex);
BandSpec.Update(Settings, SpectrumSettings);
return InBandSpecs.Add_GetRef(MoveTemp(BandSpec));
}
// Calls update on all band specs in the array.
template<typename T>
void UpdateBandSpecs(TArray<T>& InSpecs)
{
for (T& BandSpec : InSpecs)
{
BandSpec.Update(Settings, SpectrumSettings);
}
}
// Updates all band specs.
void UpdateBandSpecs()
{
UpdateBandSpecs<FNNBandSpec>(NNBandSpecs);
UpdateBandSpecs<FLerpBandSpec>(LerpBandSpecs);
UpdateBandSpecs<FQuadraticBandSpec>(QuadraticBandSpecs);
UpdateBandSpecs<FCQTBandSpec>(CQTBandSpecs);
}
template<typename T>
void ExtractBands(const FAlignedFloatBuffer& InPowerSpectrum, const TArray<T>& InBandSpecs, TArray<float>& OutValues) const
{
float* OutData = OutValues.GetData();
int32 OutNum = OutValues.Num();
const float* InData = InPowerSpectrum.GetData();
int32 InNum = InPowerSpectrum.Num();
for (const T& Spec : InBandSpecs)
{
Spec.UpdateOutputFromPowerSpectrum(InData, InNum, OutData, OutNum);
}
}
// apply metric to a band value
void ApplyMetric(TArray<float>& InValues) const
{
switch (Settings.Metric)
{
case FSpectrumBandExtractorSettings::EMetric::Magnitude:
ArraySqrtInPlace(InValues);
break;
case FSpectrumBandExtractorSettings::EMetric::Decibel:
ArrayPowerToDecibelInPlace(InValues, Settings.DecibelNoiseFloor);
break;
case FSpectrumBandExtractorSettings::EMetric::Power:
default:
break;
}
}
void Normalize(TArray<float>& InValues) const
{
// Only decibel values need to be normalized.
if (FSpectrumBandExtractorSettings::EMetric::Decibel == Settings.Metric)
{
for (float& Value : InValues)
{
if (!FMath::IsFinite(Value))
{
Value = Settings.DecibelNoiseFloor;
}
}
ArrayClampMinInPlace(InValues, Settings.DecibelNoiseFloor);
ArraySubtractByConstantInPlace(InValues, Settings.DecibelNoiseFloor);
float Range = FMath::Max(0.01f, -Settings.DecibelNoiseFloor);
ArrayMultiplyByConstantInPlace(InValues, 1.f / Range);
}
}
FSpectrumBandExtractorSettings Settings;
FSpectrumBandExtractorSpectrumSettings SpectrumSettings;
double LastTimestamp;
FAlignedFloatBuffer PowerSpectrum;
TArray<FNNBandSpec> NNBandSpecs;
TArray<FLerpBandSpec> LerpBandSpecs;
TArray<FQuadraticBandSpec> QuadraticBandSpecs;
TArray<FCQTBandSpec> CQTBandSpecs;
FAutoRange AutoRange;
};
// Creates a concreted implementation of the ISpectrumBandExtractor interface.
TUniquePtr<ISpectrumBandExtractor> ISpectrumBandExtractor::CreateSpectrumBandExtractor(const FSpectrumBandExtractorSettings& InSettings)
{
return MakeUnique<FSpectrumBandExtractor>(InSettings);
}
FSpectrumAnalyzer::FSpectrumAnalyzer()
: CurrentSettings(FSpectrumAnalyzerSettings())
, bSettingsWereUpdated(false)
, bIsInitialized(false)
, SampleRate(0.0f)
, Window(CurrentSettings.WindowType, (int32)CurrentSettings.FFTSize, 1, false)
, SampleCounter(0)
, InputQueue(FMath::Max((int32)CurrentSettings.FFTSize * 4, 4096))
, FrequencyBuffer((int32)CurrentSettings.FFTSize)
, LockedBufferTimestamp(0)
, LockedFrequencyVector(nullptr)
{
}
FSpectrumAnalyzer::FSpectrumAnalyzer(const FSpectrumAnalyzerSettings& InSettings, float InSampleRate)
: CurrentSettings(InSettings)
, bSettingsWereUpdated(false)
, bIsInitialized(true)
, SampleRate(InSampleRate)
, Window(InSettings.WindowType, (int32)InSettings.FFTSize, 1, false)
, SampleCounter(0)
, InputQueue(FMath::Max((int32)CurrentSettings.FFTSize * 4, 4096))
, FrequencyBuffer((int32)InSettings.FFTSize)
, LockedBufferTimestamp(0)
, LockedFrequencyVector(nullptr)
{
ResetSettings();
}
FSpectrumAnalyzer::FSpectrumAnalyzer(float InSampleRate)
: CurrentSettings(FSpectrumAnalyzerSettings())
, bSettingsWereUpdated(false)
, bIsInitialized(true)
, SampleRate(InSampleRate)
, Window(CurrentSettings.WindowType, (int32)CurrentSettings.FFTSize, 1, false)
, SampleCounter(0)
, InputQueue(FMath::Max((int32)CurrentSettings.FFTSize * 4, 4096))
, FrequencyBuffer((int32)CurrentSettings.FFTSize)
, LockedBufferTimestamp(0)
, LockedFrequencyVector(nullptr)
{
ResetSettings();
}
void FSpectrumAnalyzer::Init(float InSampleRate)
{
FSpectrumAnalyzerSettings DefaultSettings = FSpectrumAnalyzerSettings();
Init(DefaultSettings, InSampleRate);
}
void FSpectrumAnalyzer::Init(const FSpectrumAnalyzerSettings& InSettings, float InSampleRate)
{
CurrentSettings = InSettings;
bSettingsWereUpdated = false;
SampleRate = InSampleRate;
SampleCounter.Set(0);
InputQueue.SetCapacity(FMath::Max((int32)CurrentSettings.FFTSize * 4, 4096));
FrequencyBuffer.Reset((int32)CurrentSettings.FFTSize);
ResetSettings();
bIsInitialized = true;
}
void FSpectrumAnalyzer::ResetSettings()
{
// If the game thread has locked a frequency vector, we can't resize our buffers under it.
// Thus, wait until it's unlocked.
if (LockedFrequencyVector != nullptr)
{
return;
}
Window = FWindow(CurrentSettings.WindowType, (int32)CurrentSettings.FFTSize, 1, false);
FFTSize = (int32) CurrentSettings.FFTSize;
int32 Log2FFTSize = 9;
if (FFTSize > 0)
{
// FFTSize must be log2
check(FMath::CountBits(FFTSize) == 1);
Log2FFTSize = FMath::CountTrailingZeros(FFTSize);
}
AnalysisTimeDomainBuffer.Reset();
if (FMath::IsNearlyZero(CurrentSettings.HopSize))
{
HopInSamples = GetCOLAHopSizeForWindow(CurrentSettings.WindowType, (uint32)CurrentSettings.FFTSize);
}
else
{
HopInSamples = FMath::FloorToInt((float)CurrentSettings.FFTSize * CurrentSettings.HopSize);
}
// Create a new FFT
FFFTSettings FFTSettings;
FFTSettings.Log2Size = Log2FFTSize;
FFTSettings.bArrays128BitAligned = true;
FFTSettings.bEnableHardwareAcceleration = true;
FFT = FFFTFactory::NewFFTAlgorithm(FFTSettings);
if (!FFT.IsValid())
{
if (FFFTFactory::AreFFTSettingsSupported(FFTSettings))
{
UE_LOG(LogSignalProcessing, Error, TEXT("Failed to create fft for supported settings."))
}
else
{
UE_LOG(LogSignalProcessing, Warning, TEXT("FFT Settings are unsupported."))
}
FFTScaling = EFFTScaling::None;
if (FFTSize > 0)
{
AnalysisTimeDomainBuffer.AddZeroed(FFTSize);
FrequencyBuffer.Reset(FFTSize);
}
}
else
{
int32 NumFFTInput = FFT->NumInputFloats();
int32 NumFFTOutput = FFT->NumOutputFloats();
FFTScaling = FFT->ForwardScaling();
if (NumFFTInput > 0)
{
AnalysisTimeDomainBuffer.AddUninitialized(NumFFTInput);
}
FrequencyBuffer.Reset(NumFFTOutput);
}
bSettingsWereUpdated = false;
}
void FSpectrumAnalyzer::PerformInterpolation(const FAlignedFloatBuffer& InComplexBuffer, FSpectrumAnalyzer::EPeakInterpolationMethod InMethod, const float InFreq, float& OutReal, float& OutImag)
{
const float* InComplexData = InComplexBuffer.GetData();
const int32 VectorLength = InComplexBuffer.Num();
const int32 NyquistPosition = VectorLength - 2;
const float Nyquist = SampleRate / 2.f;
// Fractional position in the frequency vector in terms of indices.
// float Position = NyquistPosition + (InFreq / Nyquist);
const float NormalizedFreq = (InFreq / Nyquist);
float Position = InFreq >= 0 ? (NormalizedFreq * VectorLength) : 0.f;
switch (InMethod)
{
case Audio::FSpectrumAnalyzer::EPeakInterpolationMethod::NearestNeighbor:
{
int32 Index = FMath::RoundToInt(Position) & SpectrumAnalyzerIntrinsics::EvenNumberMask;
Index = FMath::Clamp(Index, 0, NyquistPosition);
OutReal = InComplexData[Index];
OutImag = InComplexData[Index + 1];
break;
}
case Audio::FSpectrumAnalyzer::EPeakInterpolationMethod::Linear:
{
int32 LowerIndex = FMath::FloorToInt(Position) & SpectrumAnalyzerIntrinsics::EvenNumberMask;
int32 UpperIndex = LowerIndex + 2;
LowerIndex = FMath::Clamp(LowerIndex, 0, NyquistPosition);
UpperIndex = FMath::Clamp(UpperIndex, 0, NyquistPosition);
const float PositionFraction = Position - LowerIndex;
const float y1Real = InComplexData[LowerIndex];
const float y2Real = InComplexData[UpperIndex];
OutReal = FMath::Lerp<float>(y1Real, y1Real, PositionFraction);
const float y1Imag = InComplexData[LowerIndex + 1];
const float y2Imag = InComplexData[UpperIndex + 1];
OutImag = FMath::Lerp<float>(y1Imag, y2Imag, PositionFraction);
break;
}
case Audio::FSpectrumAnalyzer::EPeakInterpolationMethod::Quadratic:
{
// Note: math here does not interpolate quadratically.
const int32 MidIndex = FMath::Clamp(FMath::RoundToInt(Position) & SpectrumAnalyzerIntrinsics::EvenNumberMask, 0, NyquistPosition);
const int32 LowerIndex = FMath::Max(0, MidIndex - 2);
const int32 UpperIndex = FMath::Min(NyquistPosition, MidIndex + 2);
const float y1Real = InComplexData[LowerIndex];
const float y2Real = InComplexData[MidIndex];
const float y3Real = InComplexData[UpperIndex];
const float InterpReal = (y3Real - y1Real) / (2.f * (2.f * y2Real - y1Real - y3Real));
OutReal = InterpReal;
const float y1Imag = InComplexData[LowerIndex + 1];
const float y2Imag = InComplexData[MidIndex + 1];
const float y3Imag = InComplexData[UpperIndex + 1];
const float InterpImag = (y3Imag - y1Imag) / (2.f * (2.f * y2Imag - y1Imag - y3Imag));
OutImag = InterpImag;
break;
}
default:
break;
}
}
void FSpectrumAnalyzer::SetSettings(const FSpectrumAnalyzerSettings& InSettings)
{
CurrentSettings = InSettings;
bSettingsWereUpdated = true;
}
void FSpectrumAnalyzer::GetSettings(FSpectrumAnalyzerSettings& OutSettings)
{
OutSettings = CurrentSettings;
}
float FSpectrumAnalyzer::GetMagnitudeForFrequency(float InFrequency, FSpectrumAnalyzer::EPeakInterpolationMethod InMethod)
{
if (!bIsInitialized)
{
return 0.f;
}
const FAlignedFloatBuffer* OutVector = nullptr;
bool bShouldUnlockBuffer = true;
if (LockedFrequencyVector)
{
OutVector = LockedFrequencyVector;
bShouldUnlockBuffer = false;
}
else
{
OutVector = &FrequencyBuffer.LockMostRecentBuffer();
}
// Perform work.
if (OutVector)
{
float OutMagnitude = 0.0f;
float InterpolatedReal, InterpolatedImag;
PerformInterpolation(*OutVector, InMethod, InFrequency, InterpolatedReal, InterpolatedImag);
OutMagnitude = FMath::Sqrt((InterpolatedReal * InterpolatedReal) + (InterpolatedImag * InterpolatedImag));
if (bShouldUnlockBuffer)
{
FrequencyBuffer.UnlockBuffer();
LockedBufferTimestamp = 0.0;
}
return OutMagnitude;
}
// If we got here, something went wrong, so just output zero.
return 0.0f;
}
float FSpectrumAnalyzer::GetNormalizedMagnitudeForFrequency(float InFrequency, EPeakInterpolationMethod InMethod)
{
float Norm = static_cast<uint16>(CurrentSettings.FFTSize) * 0.5f;
if (Norm > 0.0f)
{
return GetMagnitudeForFrequency(InFrequency, InMethod) / Norm;
}
return 0.f;
}
float FSpectrumAnalyzer::GetPhaseForFrequency(float InFrequency, FSpectrumAnalyzer::EPeakInterpolationMethod InMethod)
{
if (!bIsInitialized)
{
return 0.f;
}
const FAlignedFloatBuffer* OutVector = nullptr;
bool bShouldUnlockBuffer = true;
if (LockedFrequencyVector)
{
OutVector = LockedFrequencyVector;
bShouldUnlockBuffer = false;
}
else
{
OutVector = &FrequencyBuffer.LockMostRecentBuffer();
}
// Perform work.
if (OutVector)
{
float OutPhase = 0.0f;
float InterpolatedReal, InterpolatedImag;
PerformInterpolation(*OutVector, InMethod, InFrequency, InterpolatedReal, InterpolatedImag);
OutPhase = FMath::Atan2(InterpolatedImag, InterpolatedReal);
if (bShouldUnlockBuffer)
{
FrequencyBuffer.UnlockBuffer();
LockedBufferTimestamp = 0.0;
}
return OutPhase;
}
// If we got here, something went wrong, so just output zero.
return 0.0f;
}
// Return bands extracted by band extractor.
void FSpectrumAnalyzer::GetBands(ISpectrumBandExtractor& InExtractor, TArray<float>& OutValues)
{
OutValues.Reset();
if (!bIsInitialized)
{
return;
}
const FAlignedFloatBuffer* AnalysisBuffer = nullptr;
bool bShouldUnlockBuffer = true;
FSpectrumBandExtractorSpectrumSettings ExtractorSettings;
ExtractorSettings.SampleRate = SampleRate;
ExtractorSettings.FFTSize = FFTSize;
ExtractorSettings.FFTScaling = FFTScaling;
ExtractorSettings.WindowType = Window.GetWindowType();
// This should have minimal cost if settings have not changed between calls.
InExtractor.SetSpectrumSettings(ExtractorSettings);
if (LockedFrequencyVector)
{
AnalysisBuffer = LockedFrequencyVector;
bShouldUnlockBuffer = false;
}
else
{
AnalysisBuffer = &FrequencyBuffer.LockMostRecentBuffer(LockedBufferTimestamp);
}
// Perform work.
if (AnalysisBuffer)
{
InExtractor.ExtractBands(*AnalysisBuffer, LockedBufferTimestamp, OutValues);
if (bShouldUnlockBuffer)
{
FrequencyBuffer.UnlockBuffer();
LockedBufferTimestamp = 0.0;
}
}
}
void FSpectrumAnalyzer::LockOutputBuffer()
{
if (!bIsInitialized)
{
return;
}
if (LockedFrequencyVector != nullptr)
{
FrequencyBuffer.UnlockBuffer();
LockedBufferTimestamp = 0.0;
}
LockedFrequencyVector = &FrequencyBuffer.LockMostRecentBuffer(LockedBufferTimestamp);
}
void FSpectrumAnalyzer::UnlockOutputBuffer()
{
if (!bIsInitialized)
{
return;
}
if (LockedFrequencyVector != nullptr)
{
FrequencyBuffer.UnlockBuffer();
LockedFrequencyVector = nullptr;
LockedBufferTimestamp = 0.0;
}
}
bool FSpectrumAnalyzer::PushAudio(const TSampleBuffer<float>& InBuffer)
{
check(InBuffer.GetNumChannels() == 1);
return PushAudio(InBuffer.GetData(), InBuffer.GetNumSamples());
}
bool FSpectrumAnalyzer::PushAudio(const float* InBuffer, int32 NumSamples)
{
SampleCounter.Add(NumSamples);
return InputQueue.Push(InBuffer, NumSamples) == NumSamples;
}
bool FSpectrumAnalyzer::PerformAnalysisIfPossible(bool bUseLatestAudio)
{
if (!IsInitialized())
{
return false;
}
// If settings were updated, perform resizing and parameter updates here:
if (bSettingsWereUpdated)
{
ResetSettings();
}
FAlignedFloatBuffer& FFTOutput = FrequencyBuffer.StartWorkOnBuffer();
// If we have enough audio pushed to the spectrum analyzer and we have an available buffer to work in,
// we can start analyzing.
uint32 RequiredSize = FMath::Max(FFTSize, HopInSamples);
if (InputQueue.Num() >= RequiredSize)
{
int64 WindowSampleCenterIndex = 0;
float* TimeDomainBuffer = AnalysisTimeDomainBuffer.GetData();
if (bUseLatestAudio)
{
WindowSampleCenterIndex = SampleCounter.GetValue() - (FFTSize / 2);
// If we are only using the latest audio, scrap the oldest audio in the InputQueue:
InputQueue.SetNum((uint32)FFTSize);
InputQueue.Pop(TimeDomainBuffer, FFTSize);
}
else
{
WindowSampleCenterIndex = SampleCounter.GetValue() - InputQueue.Num() + (FFTSize / 2);
// Perform pop/peek here based on FFT size and hop amount.
InputQueue.Peek(TimeDomainBuffer, FFTSize);
InputQueue.Pop(HopInSamples);
}
double Timestamp = static_cast<double>(WindowSampleCenterIndex) / FMath::Max(SampleRate, 1.f);
// apply window if necessary.
Window.ApplyToBuffer(TimeDomainBuffer);
// Perform FFT.
if (FFT.IsValid())
{
check(AnalysisTimeDomainBuffer.Num() == FFT->NumInputFloats());
check(FFTOutput.Num() == FFT->NumOutputFloats());
FFT->ForwardRealToComplex(TimeDomainBuffer, FFTOutput.GetData());
}
else
{
if (FFTOutput.Num() > 0)
{
FMemory::Memset(FFTOutput.GetData(), 0, sizeof(float) * FFTOutput.Num());
}
}
// We're done, so unlock this vector.
FrequencyBuffer.StopWorkOnBuffer(Timestamp);
return true;
}
else
{
return false;
}
}
bool FSpectrumAnalyzer::IsInitialized()
{
return bIsInitialized;
}
static const int32 SpectrumAnalyzerBufferSize = 4;
FSpectrumAnalyzerBuffer::FSpectrumAnalyzerBuffer()
: OutputIndex(0)
, InputIndex(0)
{
}
FSpectrumAnalyzerBuffer::FSpectrumAnalyzerBuffer(int32 InNum)
{
Reset(InNum);
}
void FSpectrumAnalyzerBuffer::Reset(int32 InNum)
{
FScopeLock ScopeLock(&BufferIndicesCriticalSection);
static_assert(SpectrumAnalyzerBufferSize > 2, "Please ensure that SpectrumAnalyzerBufferSize is greater than 2.");
ComplexBuffers.Reset();
for (int32 Index = 0; Index < SpectrumAnalyzerBufferSize; Index++)
{
FAlignedFloatBuffer& Buffer = ComplexBuffers.Emplace_GetRef();
if (InNum > 0)
{
Buffer.AddZeroed(InNum);
}
}
Timestamps.Reset();
Timestamps.AddZeroed(SpectrumAnalyzerBufferSize);
InputIndex = 0;
OutputIndex = 0;
}
void FSpectrumAnalyzerBuffer::IncrementInputIndex()
{
FScopeLock ScopeLock(&BufferIndicesCriticalSection);
InputIndex = (InputIndex + 1) % SpectrumAnalyzerBufferSize;
if (InputIndex == OutputIndex)
{
InputIndex = (InputIndex + 1) % SpectrumAnalyzerBufferSize;
}
check(InputIndex != OutputIndex);
}
void FSpectrumAnalyzerBuffer::IncrementOutputIndex()
{
FScopeLock ScopeLock(&BufferIndicesCriticalSection);
OutputIndex = (OutputIndex + 1) % SpectrumAnalyzerBufferSize;
if (InputIndex == OutputIndex)
{
OutputIndex = (OutputIndex + 1) % SpectrumAnalyzerBufferSize;
}
check(InputIndex != OutputIndex);
}
FAlignedFloatBuffer& FSpectrumAnalyzerBuffer::StartWorkOnBuffer()
{
return ComplexBuffers[InputIndex];
}
void FSpectrumAnalyzerBuffer::StopWorkOnBuffer(double InTimestamp)
{
Timestamps[InputIndex] = InTimestamp;
IncrementInputIndex();
}
const FAlignedFloatBuffer& FSpectrumAnalyzerBuffer::LockMostRecentBuffer(double& OutTimestamp) const
{
OutTimestamp = Timestamps[OutputIndex];
return ComplexBuffers[OutputIndex];
}
const FAlignedFloatBuffer& FSpectrumAnalyzerBuffer::LockMostRecentBuffer() const
{
return ComplexBuffers[OutputIndex];
}
void FSpectrumAnalyzerBuffer::UnlockBuffer()
{
IncrementOutputIndex();
}
void FSpectrumAnalysisAsyncWorker::DoWork()
{
FScopeLock AbandonLock(&NonAbandonableSection);
if (!bIsAbandoned)
{
TSharedPtr<FSpectrumAnalyzer, ESPMode::ThreadSafe> AnalyzerSharedPtr = AnalyzerWeakPtr.Pin();
if (AnalyzerSharedPtr.IsValid())
{
AnalyzerSharedPtr->PerformAnalysisIfPossible(bUseLatestAudio);
}
}
}
void FSpectrumAnalysisAsyncWorker::Abandon()
{
FScopeLock AbandonLock(&NonAbandonableSection);
bIsAbandoned = true;
}
FAsyncSpectrumAnalyzer::FAsyncSpectrumAnalyzer()
: Analyzer(MakeShared<FSpectrumAnalyzer, ESPMode::ThreadSafe>())
{
}
FAsyncSpectrumAnalyzer::FAsyncSpectrumAnalyzer(float InSampleRate)
: Analyzer(MakeShared<FSpectrumAnalyzer, ESPMode::ThreadSafe>(InSampleRate))
{
}
FAsyncSpectrumAnalyzer::FAsyncSpectrumAnalyzer(const FSpectrumAnalyzerSettings& InSettings, float InSampleRate)
: Analyzer(MakeShared<FSpectrumAnalyzer, ESPMode::ThreadSafe>(InSettings, InSampleRate))
{
}
FAsyncSpectrumAnalyzer::~FAsyncSpectrumAnalyzer()
{
if (AsyncAnalysisTask.IsValid())
{
if (!AsyncAnalysisTask->IsDone())
{
if (!AsyncAnalysisTask->Cancel())
{
const bool bDoWorkOnThisThreadIfNotStarted = true;
AsyncAnalysisTask->EnsureCompletion(bDoWorkOnThisThreadIfNotStarted);
}
}
}
}
void FAsyncSpectrumAnalyzer::Init(float InSampleRate)
{
Analyzer->Init(InSampleRate);
}
void FAsyncSpectrumAnalyzer::Init(const FSpectrumAnalyzerSettings& InSettings, float InSampleRate)
{
Analyzer->Init(InSettings, InSampleRate);
}
bool FAsyncSpectrumAnalyzer::IsInitialized()
{
return Analyzer->IsInitialized();
}
void FAsyncSpectrumAnalyzer::SetSettings(const FSpectrumAnalyzerSettings& InSettings)
{
Analyzer->SetSettings(InSettings);
}
void FAsyncSpectrumAnalyzer::GetSettings(FSpectrumAnalyzerSettings& OutSettings)
{
Analyzer->GetSettings(OutSettings);
}
float FAsyncSpectrumAnalyzer::GetMagnitudeForFrequency(float InFrequency, FSpectrumAnalyzer::EPeakInterpolationMethod InMethod)
{
return Analyzer->GetMagnitudeForFrequency(InFrequency, InMethod);
}
float FAsyncSpectrumAnalyzer::GetNormalizedMagnitudeForFrequency(float InFrequency, FSpectrumAnalyzer::EPeakInterpolationMethod InMethod)
{
return Analyzer->GetNormalizedMagnitudeForFrequency(InFrequency, InMethod);
}
float FAsyncSpectrumAnalyzer::GetPhaseForFrequency(float InFrequency, FSpectrumAnalyzer::EPeakInterpolationMethod InMethod)
{
return Analyzer->GetPhaseForFrequency(InFrequency, InMethod);
}
void FAsyncSpectrumAnalyzer::GetBands(ISpectrumBandExtractor& InExtractor, TArray<float>& OutValues)
{
Analyzer->GetBands(InExtractor, OutValues);
}
void FAsyncSpectrumAnalyzer::LockOutputBuffer()
{
Analyzer->LockOutputBuffer();
}
void FAsyncSpectrumAnalyzer::UnlockOutputBuffer()
{
Analyzer->UnlockOutputBuffer();
}
bool FAsyncSpectrumAnalyzer::PushAudio(const TSampleBuffer<float>& InBuffer)
{
return Analyzer->PushAudio(InBuffer);
}
bool FAsyncSpectrumAnalyzer::PushAudio(const float* InBuffer, int32 NumSamples)
{
return Analyzer->PushAudio(InBuffer, NumSamples);
}
bool FAsyncSpectrumAnalyzer::PerformAnalysisIfPossible(bool bUseLatestAudio)
{
return Analyzer->PerformAnalysisIfPossible(bUseLatestAudio);
}
bool FAsyncSpectrumAnalyzer::PerformAsyncAnalysisIfPossible(bool bUseLatestAudio)
{
if (!IsInitialized())
{
return false;
}
// if bAsync is true, kick off a new task if one isn't in flight already, and return.
if (!AsyncAnalysisTask.IsValid())
{
AsyncAnalysisTask.Reset(new FSpectrumAnalyzerTask(Analyzer, bUseLatestAudio));
AsyncAnalysisTask->StartBackgroundTask();
}
else if (AsyncAnalysisTask->IsDone())
{
AsyncAnalysisTask->StartBackgroundTask();
}
return true;
}
}