AudioResampler.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Containers/Array.h"
#include "Containers/ContainerAllocationPolicies.h"
#include "CoreMinimal.h"
#include "HAL/Platform.h"
#include "Logging/LogMacros.h"
#include "Templates/UniquePtr.h"
 
// TODO: Move BufferVectorOperations AUDIO_BUFFER_ALIGNMENT
// define to more central location and reference here.
#define AUDIO_BUFFER_ALIGNMENT 16
 
DECLARE_LOG_CATEGORY_EXTERN(LogAudioResampler, Warning, All);
 
namespace Audio
{
    // TODO: Move BufferVectorOperations Aligned...Buffer
    // defines to more central location and reference here.
    namespace VectorOps
    {
        using FAlignedFloatBuffer = TArray<float, TAlignedHeapAllocator<AUDIO_BUFFER_ALIGNMENT>>;
    } // namespace VectorOps
 
    enum class EResamplingMethod : uint8
    {
        BestSinc = 0,
        ModerateSinc = 1,
        FastSinc = 2,
        ZeroOrderHold = 3,
        Linear = 4
    };
 
    struct FResamplingParameters
    {
        EResamplingMethod ResamplerMethod;
        int32 NumChannels;
        float SourceSampleRate;
        float DestinationSampleRate;
        VectorOps::FAlignedFloatBuffer& InputBuffer;
    };
 
    struct FResamplerResults
    {
        VectorOps::FAlignedFloatBuffer* OutBuffer;
 
        float ResultingSampleRate;
 
        int32 InputFramesUsed;
 
        int32 OutputFramesGenerated;
 
        FResamplerResults()
            : OutBuffer(nullptr)
            , ResultingSampleRate(0.0f)
            , InputFramesUsed(0)
            , OutputFramesGenerated(0)
        {}
    };
 
    // Get how large the output buffer should be for a resampling operation.
    AUDIOPLATFORMCONFIGURATION_API int32 GetOutputBufferSize(const FResamplingParameters& InParameters);
 
    // Simple, inline resampler. Returns true on success, false otherwise.
    AUDIOPLATFORMCONFIGURATION_API bool Resample(const FResamplingParameters& InParameters, FResamplerResults& OutData);
 
 
    class FResamplerImpl;
 
    class FResampler
    {
    public:
        AUDIOPLATFORMCONFIGURATION_API FResampler();
        AUDIOPLATFORMCONFIGURATION_API ~FResampler();
 
        AUDIOPLATFORMCONFIGURATION_API void Init(EResamplingMethod ResamplingMethod, float StartingSampleRateRatio, int32 InNumChannels);
        AUDIOPLATFORMCONFIGURATION_API void SetSampleRateRatio(float InRatio);
        AUDIOPLATFORMCONFIGURATION_API int32 ProcessAudio(float* InAudioBuffer, int32 InSamples, bool bEndOfInput, float* OutAudioBuffer, int32 MaxOutputFrames, int32& OutNumFrames);
 
    private:
        TUniquePtr<FResamplerImpl> CreateImpl();
        TUniquePtr<FResamplerImpl> Impl;
    };
    
} // namespace Audio