RuntimeResampler.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "DSP/BufferVectorOperations.h"
#include "DSP/Dsp.h"
#include "DSP/MultichannelBuffer.h"
 
#define UE_API SIGNALPROCESSING_API
 
namespace Audio
{
    class FRuntimeResampler
    {
    public:
 
        static UE_API const float MaxFrameRatio;
        static UE_API const float MinFrameRatio;
 
        UE_API FRuntimeResampler(int32 InNumChannels);
 
        UE_API void SetFrameRatio(float InRatio, int32 InNumFramesToInterpolate = 0);
 
        UE_API int32 GetNumInputFramesNeededToProduceOutputFrames(int32 InNumOutputFrames) const;
 
        UE_API int32 GetNumOutputFramesProducedByInputFrames(int32 InNumInputFrames) const;
 
        UE_API int32 ProcessCircularBuffer(FMultichannelCircularBuffer& InAudio, FMultichannelBuffer& OutAudio);
 
        UE_API int32 ProcessCircularBuffer(FMultichannelCircularBuffer& InAudio, FMultichannelBufferView& OutAudio);
 
        UE_API void ProcessInterleaved(TArrayView<const float> Input, TArrayView<float> Output, int32& OutNumInputFramesConsumed, int32& OutNumOutputFramesProduced);
 
        UE_API void Reset(int32 InNumChannels);
 
    private:
        int64 MapOutputFrameToInputFrameFP(int32 InOutputFrameIndex) const;
 
        struct ResamplingParameters
        {
            TConstArrayView<const float*> InputAudio;
            int32 InputStride = 0;
            int32 NumInputFrames = -1;
            TConstArrayView<float*> OutputAudio;
            int32 OutputStride = 0;
            int32 NumOutputFrames = -1;
 
            int32 OutNumInputFramesConsumed = 0;
            int32 OutNumOutputFramesProduced = 0;
        };
 
        void ProcessAudioInternal(ResamplingParameters& Parameters);
 
        void ProcessAudioInBatches(ResamplingParameters& Parameters, int32 MaxSamplesPerBatch);
 
        bool DoDirectCopy(ResamplingParameters& Parameters);
 
        void GenericResamplingCore(const ResamplingParameters& Parameters, int32& OutInputFrameIndexFP, uint32& OutInputFrameRatioFP, int32 OutputSampleIndex, int32 OutputEndIndex);
        void MonoResamplingCore(const float* Input, float* Output, int32& OutInputFrameIndexFP, uint32& OutInputFrameRatioFP, int32 OutputSampleIndex, int32 OutputEndIndex);
        void StereoInterleavedResamplingCore(const float* Input, float* Output, int32& OutInputFrameIndexFP, uint32& OutInputFrameRatioFP, int32 OutputSampleIndex, int32 OutputEndIndex);
        void StereoDeinterleavedResamplingCore(const float* InputLeft, const float* InputRight, float* OutputLeft, float* OutputRight, int32& OutInputFrameIndexFP, uint32& OutInputFrameRatioFP, int32 OutputSampleIndex, int32 OutputEndIndex);
 
        template<typename OutputBufferType, typename OutputChannelType>
        int32 ProcessCircularBufferGeneric(FMultichannelCircularBuffer& InAudio, OutputBufferType& OutAudio);
 
        static const int32 FPScale;
        static const float FPScaleFloat;
 
        int32 CurrentInputFrameIndexFP = 0;
        uint32 CurrentFrameRatioFP = 0;
        uint32 TargetFrameRatioFP = 0;
        int32 FrameRatioFrameDeltaFP = 0;
        int32 NumFramesToInterpolate = 0;
 
        TArray<float, TInlineAllocator<2>> PreviousFrame;
        TArray<const float*, TInlineAllocator<2>> TempInputPointers;
        TArray<float*, TInlineAllocator<2>> TempOutputPointers;
    };
}
 
#undef UE_API