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81 lines
3.0 KiB
81 lines
3.0 KiB
/*
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* Copyright 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <algorithm> // Do NOT delete. Needed for LLVM. See #1746
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#include <cassert>
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#include <math.h>
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#include "SincResamplerStereo.h"
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using namespace RESAMPLER_OUTER_NAMESPACE::resampler;
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#define STEREO 2
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SincResamplerStereo::SincResamplerStereo(const MultiChannelResampler::Builder &builder)
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: SincResampler(builder) {
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assert(builder.getChannelCount() == STEREO);
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}
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void SincResamplerStereo::writeFrame(const float *frame) {
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// Move cursor before write so that cursor points to last written frame in read.
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if (--mCursor < 0) {
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mCursor = getNumTaps() - 1;
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}
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float *dest = &mX[mCursor * STEREO];
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const int offset = mNumTaps * STEREO;
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// Write each channel twice so we avoid having to wrap when running the FIR.
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const float left = frame[0];
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const float right = frame[1];
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// Put ordered writes together.
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dest[0] = left;
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dest[1] = right;
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dest[offset] = left;
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dest[1 + offset] = right;
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}
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// Multiply input times windowed sinc function.
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void SincResamplerStereo::readFrame(float *frame) {
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// Clear accumulator for mixing.
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std::fill(mSingleFrame.begin(), mSingleFrame.end(), 0.0);
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std::fill(mSingleFrame2.begin(), mSingleFrame2.end(), 0.0);
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// Determine indices into coefficients table.
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double tablePhase = getIntegerPhase() * mPhaseScaler;
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int index1 = static_cast<int>(floor(tablePhase));
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float *coefficients1 = &mCoefficients[static_cast<size_t>(index1)
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* static_cast<size_t>(getNumTaps())];
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int index2 = (index1 + 1);
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float *coefficients2 = &mCoefficients[static_cast<size_t>(index2)
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* static_cast<size_t>(getNumTaps())];
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float *xFrame = &mX[static_cast<size_t>(mCursor) * static_cast<size_t>(getChannelCount())];
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for (int i = 0; i < mNumTaps; i++) {
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float coefficient1 = *coefficients1++;
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float coefficient2 = *coefficients2++;
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for (int channel = 0; channel < getChannelCount(); channel++) {
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float sample = *xFrame++;
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mSingleFrame[channel] += sample * coefficient1;
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mSingleFrame2[channel] += sample * coefficient2;
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}
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}
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// Interpolate and copy to output.
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float fraction = tablePhase - index1;
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for (int channel = 0; channel < getChannelCount(); channel++) {
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float low = mSingleFrame[channel];
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float high = mSingleFrame2[channel];
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frame[channel] = low + (fraction * (high - low));
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}
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}
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