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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/>.
*/
#include "LinearResampler.h"
using namespace SRCTools;
LinearResampler::LinearResampler(double sourceSampleRate, double targetSampleRate) :
inputToOutputRatio(sourceSampleRate / targetSampleRate),
position(1.0) // Preload delay line which effectively makes resampler zero phase
{}
void LinearResampler::process(const FloatSample *&inSamples, unsigned int &inLength, FloatSample *&outSamples, unsigned int &outLength) {
if (inLength == 0) return;
while (outLength > 0) {
while (1.0 <= position) {
position--;
inLength--;
for (unsigned int chIx = 0; chIx < LINEAR_RESAMPER_CHANNEL_COUNT; ++chIx) {
lastInputSamples[chIx] = *(inSamples++);
}
if (inLength == 0) return;
}
for (unsigned int chIx = 0; chIx < LINEAR_RESAMPER_CHANNEL_COUNT; chIx++) {
*(outSamples++) = FloatSample(lastInputSamples[chIx] + position * (inSamples[chIx] - lastInputSamples[chIx]));
}
outLength--;
position += inputToOutputRatio;
}
}
unsigned int LinearResampler::estimateInLength(const unsigned int outLength) const {
return static_cast<unsigned int>(outLength * inputToOutputRatio);
}
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