68 lines
1.9 KiB
C++
68 lines
1.9 KiB
C++
/*
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* Copyright 2022 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>
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#include <math.h>
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#include <unistd.h>
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#include "FlowGraphNode.h"
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#include "Limiter.h"
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using namespace FLOWGRAPH_OUTER_NAMESPACE::flowgraph;
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Limiter::Limiter(int32_t channelCount)
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: FlowGraphFilter(channelCount) {
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}
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int32_t Limiter::onProcess(int32_t numFrames) {
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const float *inputBuffer = input.getBuffer();
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float *outputBuffer = output.getBuffer();
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int32_t numSamples = numFrames * output.getSamplesPerFrame();
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// Cache the last valid output to reduce memory read/write
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float lastValidOutput = mLastValidOutput;
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for (int32_t i = 0; i < numSamples; i++) {
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// Use the previous output if the input is NaN
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if (!isnan(*inputBuffer)) {
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lastValidOutput = processFloat(*inputBuffer);
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}
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inputBuffer++;
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*outputBuffer++ = lastValidOutput;
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}
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mLastValidOutput = lastValidOutput;
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return numFrames;
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}
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float Limiter::processFloat(float in)
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{
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float in_abs = fabsf(in);
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if (in_abs <= 1) {
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return in;
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}
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float out;
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if (in_abs < kXWhenYis3Decibels) {
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out = (kPolynomialSplineA * in_abs + kPolynomialSplineB) * in_abs + kPolynomialSplineC;
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} else {
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out = M_SQRT2;
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}
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if (in < 0) {
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out = -out;
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}
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return out;
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}
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