rewrite VU to native

native/src/vumeter.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <cstddef>
+#include <vector>
+
+namespace Visualizer {
+
+struct VUMeterSnapshot {
+    float vuLDb;
+    float vuRDb;
+    float barLDb;
+    float barRDb;
+    float peakLDb;
+    float peakRDb;
+    float correlation;
+};
+
+class VUMeterAnalyzer {
+public:
+    VUMeterAnalyzer();
+
+    void setSampleRate(float sampleRate);
+    void pushSamples(const float* leftChannel, const float* rightChannel, size_t length);
+    VUMeterSnapshot getSnapshot();
+    void reset();
+
+private:
+    void configureForSampleRate(float sampleRate);
+    void processSample(float left, float right, double& maxPeakL, double& maxPeakR);
+    void advancePeaks(double nowMs);
+    void maybeUpdatePeak(double peakDb, double nowMs, bool leftChannel);
+    double applyPeakDecay(double currentDb, double holdUntilMs, double nowMs) const;
+    void recomputeSnapshot();
+
+    static double currentTimeMs();
+    static double amplitudeToDb(double amplitude);
+    static double clampDb(double db, double minDb, double maxDb);
+
+    float sampleRate_ = 48000.0f;
+    size_t integrationWindowSamples_ = 1;
+    std::vector<double> sqL_;
+    std::vector<double> sqR_;
+    std::vector<double> cross_;
+    size_t writeIndex_ = 0;
+    size_t sampleCount_ = 0;
+    double sumSqL_ = 0.0;
+    double sumSqR_ = 0.0;
+    double sumCross_ = 0.0;
+    double barEnvelopeL_ = 0.0;
+    double barEnvelopeR_ = 0.0;
+    double barAttackCoeff_ = 0.0;
+    double barReleaseCoeff_ = 0.0;
+    double peakHoldUntilL_ = 0.0;
+    double peakHoldUntilR_ = 0.0;
+    double lastPeakUpdateMs_ = 0.0;
+    bool hasLastPeakUpdate_ = false;
+    VUMeterSnapshot snapshot_{};
+};
+
+} // namespace Visualizer