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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANALYZER_BASE_SINE_ANALYZER_H
#define ANALYZER_BASE_SINE_ANALYZER_H
#include <algorithm>
#include <cctype>
#include <iomanip>
#include <iostream>
#include "InfiniteRecording.h"
#include "LatencyAnalyzer.h"
/**
* Output a steady sine wave and analyze the return signal.
*
* Use a cosine transform to measure the predicted magnitude and relative phase of the
* looped back sine wave. Then generate a predicted signal and compare with the actual signal.
*/
class BaseSineAnalyzer : public LoopbackProcessor {
public:
BaseSineAnalyzer()
: LoopbackProcessor()
, mInfiniteRecording(64 * 1024) {}
virtual bool isOutputEnabled() { return true; }
void setMagnitude(double magnitude) {
mMagnitude = magnitude;
mScaledTolerance = mMagnitude * getTolerance();
}
double getPhaseOffset() {
ALOGD("%s(), mPhaseOffset = %f\n", __func__, mPhaseOffset);
return mPhaseOffset;
}
double getMagnitude() const {
return mMagnitude;
}
void setInputChannel(int inputChannel) {
mInputChannel = inputChannel;
}
int getInputChannel() const {
return mInputChannel;
}
void setOutputChannel(int outputChannel) {
mOutputChannel = outputChannel;
}
int getOutputChannel() const {
return mOutputChannel;
}
void setNoiseAmplitude(double noiseAmplitude) {
mNoiseAmplitude = noiseAmplitude;
}
double getNoiseAmplitude() const {
return mNoiseAmplitude;
}
double getTolerance() {
return mTolerance;
}
void setTolerance(double tolerance) {
mTolerance = tolerance;
}
// advance and wrap phase
void incrementOutputPhase() {
mOutputPhase += mPhaseIncrement;
if (mOutputPhase > M_PI) {
mOutputPhase -= (2.0 * M_PI);
}
}
/**
* @param frameData upon return, contains the reference sine wave
* @param channelCount
*/
result_code processOutputFrame(float *frameData, int channelCount) override {
float output = 0.0f;
// Output sine wave so we can measure it.
if (isOutputEnabled()) {
float sinOut = sinf(mOutputPhase);
incrementOutputPhase();
output = (sinOut * mOutputAmplitude)
+ (mWhiteNoise.nextRandomDouble() * getNoiseAmplitude());
// ALOGD("sin(%f) = %f, %f\n", mOutputPhase, sinOut, kPhaseIncrement);
}
for (int i = 0; i < channelCount; i++) {
frameData[i] = (i == mOutputChannel) ? output : 0.0f;
}
return RESULT_OK;
}
/**
* Calculate the magnitude of the component of the input signal
* that matches the analysis frequency.
* Also calculate the phase that we can use to create a
* signal that matches that component.
* The phase will be between -PI and +PI.
*/
double calculateMagnitudePhase(double *phasePtr = nullptr) {
if (mFramesAccumulated == 0) {
return 0.0;
}
double sinMean = mSinAccumulator / mFramesAccumulated;
double cosMean = mCosAccumulator / mFramesAccumulated;
double magnitude = 2.0 * sqrt((sinMean * sinMean) + (cosMean * cosMean));
if (phasePtr != nullptr) {
double phase = atan2(cosMean, sinMean);
*phasePtr = phase;
}
return magnitude;
}
/**
* Perform sin/cos analysis on each sample.
* Measure magnitude and phase on every period.
* Updates mPhaseOffset
* @param sample
* @param referencePhase
* @return true if magnitude and phase updated
*/
bool transformSample(float sample, float referencePhase) {
// Track incoming signal and slowly adjust magnitude to account
// for drift in the DRC or AGC.
mSinAccumulator += static_cast<double>(sample) * sinf(referencePhase);
mCosAccumulator += static_cast<double>(sample) * cosf(referencePhase);
mFramesAccumulated++;
// Must be a multiple of the period or the calculation will not be accurate.
if (mFramesAccumulated == mSinePeriod) {
const double coefficient = 0.1;
double magnitude = calculateMagnitudePhase(&mPhaseOffset);
ALOGD("%s(), mPhaseOffset = %f\n", __func__, mPhaseOffset);
// One pole averaging filter.
setMagnitude((mMagnitude * (1.0 - coefficient)) + (magnitude * coefficient));
resetAccumulator();
return true;
} else {
return false;
}
}
// reset the sine wave detector
virtual void resetAccumulator() {
mFramesAccumulated = 0;
mSinAccumulator = 0.0;
mCosAccumulator = 0.0;
}
void reset() override {
LoopbackProcessor::reset();
resetAccumulator();
mMagnitude = 0.0;
}
void prepareToTest() override {
LoopbackProcessor::prepareToTest();
mSinePeriod = getSampleRate() / kTargetGlitchFrequency;
mOutputPhase = 0.0f;
mInverseSinePeriod = 1.0 / mSinePeriod;
mPhaseIncrement = 2.0 * M_PI * mInverseSinePeriod;
}
protected:
// Try to get a prime period so the waveform plot changes every time.
static constexpr int32_t kTargetGlitchFrequency = 48000 / 113;
int32_t mSinePeriod = 1; // this will be set before use
double mInverseSinePeriod = 1.0;
double mPhaseIncrement = 0.0;
double mOutputPhase = 0.0;
double mOutputAmplitude = 0.75;
// If this jumps around then we are probably just hearing noise.
double mPhaseOffset = 0.0;
double mMagnitude = 0.0;
int32_t mFramesAccumulated = 0;
double mSinAccumulator = 0.0;
double mCosAccumulator = 0.0;
double mScaledTolerance = 0.0;
InfiniteRecording<float> mInfiniteRecording;
private:
int32_t mInputChannel = 0;
int32_t mOutputChannel = 0;
float mTolerance = 0.10; // scaled from 0.0 to 1.0
float mNoiseAmplitude = 0.00; // Used to experiment with warbling caused by DRC.
PseudoRandom mWhiteNoise;
};
#endif //ANALYZER_BASE_SINE_ANALYZER_H
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