ajout effets audio

Appli/Core/Src/fx_saturation.c

@@ -0,0 +1,32 @@
+#include "fx_saturation.h"
+#include <math.h>
+
+#define FX_SATURATION_DC_BLOCK_R 0.995f
+
+void FxSaturation_Init(FxSaturationState *state, FxSaturationParams *params)
+{
+    state->dc_block_x1 = 0.0f;
+    state->dc_block_y1 = 0.0f;
+
+    params->enabled = false;
+    params->drive   = 0.3f;
+    params->level   = 0.8f;
+}
+
+float FxSaturation_Process(FxSaturationState *state, const FxSaturationParams *params, float input)
+{
+    if (!params->enabled)
+    {
+        return input;
+    }
+
+    float driven = input * (1.0f + params->drive * 12.0f);
+    float shaped = tanhf(driven);
+
+    /* Le tanh sur un signal non symetrique introduit un leger DC : filtre bloqueur de DC. */
+    float y = shaped - state->dc_block_x1 + FX_SATURATION_DC_BLOCK_R * state->dc_block_y1;
+    state->dc_block_x1 = shaped;
+    state->dc_block_y1 = y;
+
+    return y * params->level;
+}