juce_ResamplingAudioSource.h

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/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2015 - ROLI Ltd.
 
   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3
 
   Details of these licenses can be found at: www.gnu.org/licenses
 
   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 
   ------------------------------------------------------------------------------
 
   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.
 
  ==============================================================================
*/
 
#ifndef JUCE_RESAMPLINGAUDIOSOURCE_H_INCLUDED
#define JUCE_RESAMPLINGAUDIOSOURCE_H_INCLUDED
 
 
//==============================================================================
class JUCE_API  ResamplingAudioSource  : public AudioSource
{
public:
    //==============================================================================
    ResamplingAudioSource (AudioSource* inputSource,
                           bool deleteInputWhenDeleted,
                           int numChannels = 2);
 
    ~ResamplingAudioSource();
 
    void setResamplingRatio (double samplesInPerOutputSample);
 
    double getResamplingRatio() const noexcept                  { return ratio; }
 
    void flushBuffers();
 
    //==============================================================================
    void prepareToPlay (int samplesPerBlockExpected, double sampleRate) override;
    void releaseResources() override;
    void getNextAudioBlock (const AudioSourceChannelInfo&) override;
 
private:
    //==============================================================================
    OptionalScopedPointer<AudioSource> input;
    double ratio, lastRatio;
    AudioSampleBuffer buffer;
    int bufferPos, sampsInBuffer;
    double subSampleOffset;
    double coefficients[6];
    SpinLock ratioLock;
    const int numChannels;
    HeapBlock<float*> destBuffers;
    HeapBlock<const float*> srcBuffers;
 
    void setFilterCoefficients (double c1, double c2, double c3, double c4, double c5, double c6);
    void createLowPass (double proportionalRate);
 
    struct FilterState
    {
        double x1, x2, y1, y2;
    };
 
    HeapBlock<FilterState> filterStates;
    void resetFilters();
 
    void applyFilter (float* samples, int num, FilterState& fs);
 
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ResamplingAudioSource)
};
 
 
#endif   // JUCE_RESAMPLINGAUDIOSOURCE_H_INCLUDED