dynamics_analyzer.cpp.hpp

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#include "fl/audio/detector/dynamics_analyzer.h"
#include "fl/audio/audio_context.h"
#include "fl/math/math.h"
#include "fl/stl/noexcept.h"
 
namespace fl {
namespace audio {
namespace detector {
 
DynamicsAnalyzer::DynamicsAnalyzer()
    : mHistorySize(86)  // ~2 seconds at 43fps
    , mHistoryIndex(0)
    , mCurrentRMS(0.0f)
    , mAverageRMS(0.0f)
    , mPeakRMS(0.0f)
    , mMinRMS(1.0f)
    , mTrend(0.0f)
    , mCompressionRatio(1.0f)
    , mPeakDecay(0.99f)
    , mSmoothingFactor(0.9f)
    , mTrendThreshold(0.15f)
    , mIsCrescendo(false)
    , mIsDiminuendo(false)
    , mPrevIsCrescendo(false)
    , mPrevIsDiminuendo(false)
    , mLastUpdateTime(0)
{
    mRMSHistory.reserve(mHistorySize);
}
 
DynamicsAnalyzer::~DynamicsAnalyzer() FL_NOEXCEPT = default;
 
void DynamicsAnalyzer::update(shared_ptr<Context> context) {
    mCurrentRMS = context->getRMS();
    u32 timestamp = context->getTimestamp();
 
    // Update peak with decay
    updatePeak(mCurrentRMS);
 
    // Add to history
    if (mRMSHistory.size() < mHistorySize) {
        mRMSHistory.push_back(mCurrentRMS);
        mHistoryIndex = mRMSHistory.size();
    } else {
        mRMSHistory[mHistoryIndex] = mCurrentRMS;
        mHistoryIndex = (mHistoryIndex + 1) % mHistorySize;
    }
 
    // Calculate average RMS from history
    float sum = 0.0f;
    for (fl::size i = 0; i < mRMSHistory.size(); i++) {
        sum += mRMSHistory[i];
    }
    mAverageRMS = (mRMSHistory.size() > 0) ? sum / mRMSHistory.size() : 0.0f;
 
    // Track minimum RMS (with slow rise to handle changing environments)
    if (mCurrentRMS < mMinRMS) {
        mMinRMS = mCurrentRMS;
    } else {
        mMinRMS += (mCurrentRMS - mMinRMS) * 0.001f;  // Very slow rise
    }
 
    // Calculate dynamic trend
    float newTrend = calculateTrend();
 
    // Smooth the trend
    mTrend = mSmoothingFactor * mTrend + (1.0f - mSmoothingFactor) * newTrend;
 
    // Determine crescendo/diminuendo state
    mPrevIsCrescendo = mIsCrescendo;
    mPrevIsDiminuendo = mIsDiminuendo;
 
    mIsCrescendo = (mTrend > mTrendThreshold);
    mIsDiminuendo = (mTrend < -mTrendThreshold);
 
    // Update compression ratio
    updateCompression();
 
    mLastUpdateTime = timestamp;
}
 
void DynamicsAnalyzer::fireCallbacks() {
    if (mIsCrescendo && !mPrevIsCrescendo && onCrescendo) {
        onCrescendo();
    }
    if (mIsDiminuendo && !mPrevIsDiminuendo && onDiminuendo) {
        onDiminuendo();
    }
    if (onDynamicTrend) {
        onDynamicTrend(mTrend);
    }
    if (onCompressionRatio) {
        onCompressionRatio(mCompressionRatio);
    }
}
 
void DynamicsAnalyzer::reset() {
    mRMSHistory.clear();
    mHistoryIndex = 0;
    mCurrentRMS = 0.0f;
    mAverageRMS = 0.0f;
    mPeakRMS = 0.0f;
    mMinRMS = 1.0f;
    mTrend = 0.0f;
    mCompressionRatio = 1.0f;
    mIsCrescendo = false;
    mIsDiminuendo = false;
    mPrevIsCrescendo = false;
    mPrevIsDiminuendo = false;
    mLastUpdateTime = 0;
}
 
float DynamicsAnalyzer::calculateTrend() {
    if (mRMSHistory.size() < 10) {
        return 0.0f;  // Not enough data
    }
 
    // Use linear regression to determine trend
    // Compare recent average to older average
    fl::size halfSize = mRMSHistory.size() / 2;
 
    float recentSum = 0.0f;
    float olderSum = 0.0f;
 
    // Recent half
    for (fl::size i = 0; i < halfSize; i++) {
        fl::size idx = (mHistoryIndex + i) % mRMSHistory.size();
        olderSum += mRMSHistory[idx];
    }
 
    // Older half
    for (fl::size i = halfSize; i < mRMSHistory.size(); i++) {
        fl::size idx = (mHistoryIndex + i) % mRMSHistory.size();
        recentSum += mRMSHistory[idx];
    }
 
    float recentAvg = recentSum / halfSize;
    float olderAvg = olderSum / halfSize;
 
    // Avoid division by zero
    if (olderAvg < 1e-6f) {
        return 0.0f;
    }
 
    // Calculate normalized trend (-1 to +1)
    float rawTrend = (recentAvg - olderAvg) / olderAvg;
 
    // Clamp to reasonable range
    return fl::max(-1.0f, fl::min(1.0f, rawTrend * 5.0f));
}
 
void DynamicsAnalyzer::updatePeak(float rms) {
    if (rms > mPeakRMS) {
        mPeakRMS = rms;
    } else {
        // Apply decay
        mPeakRMS *= mPeakDecay;
    }
}
 
void DynamicsAnalyzer::updateCompression() {
    // Calculate dynamic range compression ratio
    // Compression ratio = (peak - min) / peak
    // High compression (near 1.0) = small dynamic range
    // Low compression (near 0.0) = large dynamic range
 
    if (mPeakRMS < 1e-6f) {
        mCompressionRatio = 1.0f;
        return;
    }
 
    float dynamicRange = mPeakRMS - mMinRMS;
    mCompressionRatio = 1.0f - (dynamicRange / mPeakRMS);
 
    // Clamp to 0-1
    mCompressionRatio = fl::max(0.0f, fl::min(1.0f, mCompressionRatio));
}
 
void DynamicsAnalyzer::setHistorySize(fl::size size) {
    mHistorySize = size;
    mRMSHistory.clear();
    mRMSHistory.reserve(size);
    mHistoryIndex = 0;
}
 
void DynamicsAnalyzer::setTrendThreshold(float threshold) {
    mTrendThreshold = threshold;
}
 
void DynamicsAnalyzer::setSmoothingFactor(float alpha) {
    // Clamp to 0-1
    mSmoothingFactor = fl::max(0.0f, fl::min(1.0f, alpha));
}
 
} // namespace detector
} // namespace audio
}  // namespace fl