T13: NativeMixer mirror server pipeline (track gain/pan constant-power + brickwall limiter tanh, wired VST2/VST3 bridge, golden test 0.0001dB)

native_host/NativeMixer.cpp

@@ -0,0 +1,90 @@
+// NativeMixer.cpp — xem NativeMixer.h cho cong thuc mirror.
+#include "NativeMixer.h"
+
+namespace sonicforge {
+
+namespace {
+
+// Mirror _clamp(v, lo, hi, default) cua mastering_engine.py: NaN -> default.
+float clampDb (float v, float lo, float hi, float def)
+{
+    if (!(v == v)) // NaN
+        return def;
+    if (v < lo)
+        return lo;
+    if (v > hi)
+        return hi;
+    return v;
+}
+
+} // namespace
+
+TrackGainPan TrackGainPan::fromDbPan (float gainDb, float pan)
+{
+    TrackGainPan t;
+    t.gainLin = std::pow (10.0f, gainDb / 20.0f);
+    float p = pan;
+    if (p < -1.0f)
+        p = -1.0f;
+    else if (p > 1.0f)
+        p = 1.0f;
+    if (p == 0.0f)
+    {
+        t.panL = 1.0f;
+        t.panR = 1.0f;
+    }
+    else
+    {
+        const float theta = ((p + 1.0f) / 2.0f) * (3.14159265358979323846f / 2.0f);
+        t.panL = std::cos (theta);
+        t.panR = std::sin (theta);
+    }
+    return t;
+}
+
+void NativeMixer::setLimiter (bool active, float thresholdDb)
+{
+    m_limActive = active;
+    if (!active)
+    {
+        m_limK = 1.0f;
+        m_limTk = 1.0f;
+        return;
+    }
+    const float t = clampDb (thresholdDb, -24.0f, 0.0f, -1.0f);
+    const float tLin = std::pow (10.0f, t / 20.0f);
+    m_limK = 1.0f / (tLin > 0.02f ? tLin : 0.02f);
+    m_limTk = std::tanh (m_limK);
+}
+
+void NativeMixer::processInPlace (float* outL, float* outR, int32 frames) const
+{
+    if (!outL || !outR || frames <= 0)
+        return;
+    const float gl = m_track.gainLin * m_track.panL;
+    const float gr = m_track.gainLin * m_track.panR;
+    for (int32 i = 0; i < frames; ++i)
+    {
+        float l = outL[i] * gl;
+        float r = outR[i] * gr;
+        if (m_limActive)
+        {
+            l = std::tanh (l * m_limK) / m_limTk;
+            r = std::tanh (r * m_limK) / m_limTk;
+            // Hard clip [-1,1] — mirror render_project sau apply_mastering
+            // (chi khi mastering on; limiter off => khong clip).
+            if (l > 1.0f)
+                l = 1.0f;
+            else if (l < -1.0f)
+                l = -1.0f;
+            if (r > 1.0f)
+                r = 1.0f;
+            else if (r < -1.0f)
+                r = -1.0f;
+        }
+        outL[i] = l;
+        outR[i] = r;
+    }
+}
+
+} // namespace sonicforge