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Source/DSP/AcousticMetrics.h

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+#pragma once
+#include "DSPConstants.h"
+#include <array>
+#include <atomic>
+#include <vector> // <- 1 row added
+
+namespace FDNReverb {
+
+     // -----------------------------------------------------------------------------
+     // AcousticMetrics class
+     // -----------------------------------------------------------------------------
+     // Computes real-time acoustic metrics (D50, C50, C80, EDT).
+    //  
+     // Principle:
+     // Accumulate the squared energy of the input signal in a ring buffer,
+     // then compare it against the energy from 50 ms / 80 ms ago,
+     // and compute the D50 / C50 / C80 values.
+    //
+     // Sample-rate support:
+     // times (ms) are converted to sample counts,
+     // so 44.1 kHz through 192 kHz are supported automatically.
+    //
+     // CPU:
+     // O(1) per-sample computation (energy accumulation)
+     // CPU overhead: below ~0.5%
+     // -----------------------------------------------------------------------------
+    class AcousticMetrics {
+    public:
+        AcousticMetrics() = default;
+
+         // -- initialize --
+         // sampleRate: sample rate (Hz)
+         // analysisWindowMs: analysis window (ms). 2000 ms (2 s)
+        void prepare(double sampleRate, float analysisWindowMs = 2000.0f);
+
+         // -- per-sample state update --
+         // sample: current Wet signal sample (mono)
+        void processSample(float sample) noexcept;
+
+         // -- value getters --
+         // ranges:
+         // D50: 0.0 ~ 1.0 ( 0.3~0.9)
+        //   C50: -10 ~ +30 dB
+        //   C80: -10 ~ +30 dB
+         // EDT: 0.0 ~ 5.0 (s)
+        float getD50() const noexcept { return d50.load(std::memory_order_relaxed); }
+        float getC50() const noexcept { return c50.load(std::memory_order_relaxed); }
+        float getC80() const noexcept { return c80.load(std::memory_order_relaxed); }
+        float getEDT() const noexcept { return edt.load(std::memory_order_relaxed); }
+
+         // --- added: expose energy history for drawing ---
+         // get the instantaneous energy (squared) at a time offset in the past
+        float getEnergyAtTimeOffset(float secondsAgo) const noexcept;
+
+         // input activity detection (energy over the last 50 ms)
+        bool isActive() const noexcept;
+
+         // -- reset --
+        void reset() noexcept;
+
+    private:
+         // -- compute --
+        void updateMetrics() noexcept;
+
+         // -- parameter --
+        double sampleRate{ 48000.0 };
+        float analysisWindowMs{ 2000.0f };
+
+         // 50ms / 80ms sample count ( sample rate depends on )
+        int samples50ms{ 2400 };   // @ 48kHz
+        int samples80ms{ 3840 };   // @ 48kHz
+        int analysisWindowSamples{ 96000 };  // 2000ms @ 48kHz
+
+         // -- buffer --
+         // energy history ( squared value )
+        std::vector<float> energyHistory;
+        int historyWritePos{ 0 };
+
+         // -- cumulative energy value --
+         // 50ms cumulative energy ( time )
+        double recent50msEnergy{ 0.0 };
+         // 80ms cumulative energy ( time )
+        double recent80msEnergy{ 0.0 };
+         // entire cumulative energy
+        double totalEnergy{ 0.0 };
+
+         // EDT : energy decay tracking
+        float energyPeak{ 0.0f };
+        int energyPeakPos{ 0 };
+
+         // -- output value (atomic for thread safety) --
+        std::atomic<float> d50{ 0.0f };
+        std::atomic<float> c50{ 0.0f };
+        std::atomic<float> c80{ 0.0f };
+        std::atomic<float> edt{ 0.0f };
+
+         // -- update --
+         // sample compute ,
+         // sample interval update
+        int updateCounter{ 0 };
+         static constexpr int kUpdateInterval = 1024; // about 21ms @ 48kHz
+    };
+
+}  // namespace FDNReverb