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/* Copyright (C) 2015-2017 Sergey V. Mikayev
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 2.1 of the License, or
* (at your option) any later version.
*
* This program 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef FIR_RESAMPLER_H
#define FIR_RESAMPLER_H
#include "ResamplerStage.h"
namespace SRCTools {
typedef FloatSample FIRCoefficient;
static const unsigned int FIR_INTERPOLATOR_CHANNEL_COUNT = 2;
class FIRResampler : public ResamplerStage {
public:
FIRResampler(const unsigned int upsampleFactor, const double downsampleFactor, const FIRCoefficient kernel[], const unsigned int kernelLength);
~FIRResampler();
void process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength);
unsigned int estimateInLength(const unsigned int outLength) const;
private:
const struct Constants {
// Filter coefficients
const FIRCoefficient *taps;
// Indicates whether to interpolate filter taps
bool usePhaseInterpolation;
// Size of array of filter coefficients
unsigned int numberOfTaps;
// Upsampling factor
unsigned int numberOfPhases;
// Downsampling factor
double phaseIncrement;
// Index of last delay line element, generally greater than numberOfTaps to form a proper binary mask
unsigned int delayLineMask;
// Delay line
FloatSample(*ringBuffer)[FIR_INTERPOLATOR_CHANNEL_COUNT];
Constants(const unsigned int upsampleFactor, const double downsampleFactor, const FIRCoefficient kernel[], const unsigned int kernelLength);
} constants;
// Index of current sample in delay line
unsigned int ringBufferPosition;
// Current phase
double phase;
bool needNextInSample() const;
void addInSamples(const FloatSample *&inSamples);
void getOutSamplesStereo(FloatSample *&outSamples);
}; // class FIRResampler
} // namespace SRCTools
#endif // FIR_RESAMPLER_H
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