72 lines
3 KiB
C++
Vendored
72 lines
3 KiB
C++
Vendored
/*
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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 <cassert>
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#include <math.h>
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#include "oboe_flowgraph_resampler_SincResampler_android.h"
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using namespace RESAMPLER_OUTER_NAMESPACE::resampler;
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SincResampler::SincResampler(const MultiChannelResampler::Builder &builder)
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: MultiChannelResampler(builder)
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, mSingleFrame2(builder.getChannelCount()) {
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assert((getNumTaps() % 4) == 0); // Required for loop unrolling.
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mNumRows = kMaxCoefficients / getNumTaps(); // includes guard row
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int32_t numRowsNoGuard = mNumRows - 1;
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mPhaseScaler = (double) numRowsNoGuard / mDenominator;
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double phaseIncrement = 1.0 / numRowsNoGuard;
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generateCoefficients(builder.getInputRate(),
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builder.getOutputRate(),
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mNumRows,
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phaseIncrement,
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builder.getNormalizedCutoff());
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}
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void SincResampler::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 indexLow = static_cast<int>(floor(tablePhase));
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int indexHigh = indexLow + 1; // OK because using a guard row.
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assert (indexHigh < mNumRows);
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float *coefficientsLow = &mCoefficients[static_cast<size_t>(indexLow)
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* static_cast<size_t>(getNumTaps())];
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float *coefficientsHigh = &mCoefficients[static_cast<size_t>(indexHigh)
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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 tap = 0; tap < mNumTaps; tap++) {
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float coefficientLow = *coefficientsLow++;
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float coefficientHigh = *coefficientsHigh++;
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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 * coefficientLow;
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mSingleFrame2[channel] += sample * coefficientHigh;
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}
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}
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// Interpolate and copy to output.
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float fraction = tablePhase - indexLow;
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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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