SampleBufferReader.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "DSP/Dsp.h"
#include "SampleBuffer.h"
 
namespace Audio
{
    namespace ESeekType
    {
        enum Type
        {
            FromBeginning,
            FromCurrentPosition,
            FromEnd
        };
    }
 
    class FSampleBufferReader
    {
    public:
        SIGNALPROCESSING_API FSampleBufferReader();
        SIGNALPROCESSING_API ~FSampleBufferReader();
 
        SIGNALPROCESSING_API void Init(const int32 InSampleRate);
 
        // This must be a completely loaded buffer. This buffer reader doesn't OWN the buffer memory.
        SIGNALPROCESSING_API void SetBuffer(const int16* InBufferPtr, const int32 InNumBufferSamples, const int32 InNumChannels, const int32 InBufferSampleRate);
 
        // Seeks the buffer the given time in seconds. Returns true if succeeded.
        SIGNALPROCESSING_API void SeekTime(const float InTimeSec, const ESeekType::Type InSeekType = ESeekType::FromBeginning, const bool bWrap = true);
 
        // Sets the pitch of the buffer reader. Can be negative. Will linearly interpolate over the given time value.
        SIGNALPROCESSING_API void SetPitch(const float InPitch, const float InterpolationTimeSec = 0.0f);
 
        // Puts the wave reader into scrub mode
        SIGNALPROCESSING_API void SetScrubMode(const bool bInIsScrubMode);
        
        // Sets the scrub width. The sound will loop between the scrub width region and the current frame
        SIGNALPROCESSING_API void SetScrubTimeWidth(const float InScrubTimeWidthSec);
 
        // Returns the number of channels of this buffer.
        int32 GetNumChannels() const { return BufferNumChannels; }
 
        // Returns the number of frames of the buffer.
        int32 GetNumFrames() const { return BufferNumFrames; }
 
        // Returns the current playback position in seconds
        float GetPlaybackProgress() const { return PlaybackProgress; }
 
        // Generates the next block of audio. Returns true if it's no longer playing (reached end of the buffer and not set to wrap)
        SIGNALPROCESSING_API bool Generate(float* OutAudioBuffer, const int32 NumFrames, const int32 OutChannels, const bool bWrap = false);
 
        // Whether or not the buffer reader has a buffer
        bool HasBuffer() const { return BufferPtr != nullptr; }
 
        // Clears current buffer and resets state
        SIGNALPROCESSING_API void ClearBuffer();
 
    protected:
 
        SIGNALPROCESSING_API float GetSampleValueForChannel(const int32 Channel);
        SIGNALPROCESSING_API void UpdateScrubMinAndMax();
        SIGNALPROCESSING_API void UpdateSeekFrame();
        SIGNALPROCESSING_API float GetSampleValue(const int16* InBuffer, const int32 SampleIndex);
 
        const int16* BufferPtr;
        int32 BufferNumSamples;
        int32 BufferNumFrames;
        int32 BufferSampleRate;
        int32 BufferNumChannels;
        int32 FadeFrames;
        float FadeValue;
        float FadeIncrement;
 
        float DeviceSampleRate;
 
        // The current frame alpha
        float BasePitch;
        float PitchScale;
        Audio::FLinearEase Pitch;
 
        int32 CurrentFrameIndex;
        int32 NextFrameIndex;
        double AlphaLerp;
 
        double CurrentBufferFrameIndexInterpolated;
 
        float PlaybackProgress;
 
        double ScrubAnchorFrame;
        double ScrubMinFrame;
        double ScrubMaxFrame;
 
        double ScrubWidthFrames;
        float CurrentSeekTime;
        float CurrentScrubWidthSec;
 
        ESeekType::Type CurrentSeekType;
        bool bWrap;
        bool bIsScrubMode;
        bool bIsFinished;
    };
 
}