ajout effets audio

Appli/Core/Src/fx_reverb.c

@@ -0,0 +1,114 @@
+#include "fx_reverb.h"
+#include <string.h>
+
+/* Lignes a retard inspirees de Freeverb (Jezar), redimensionnees de 44.1kHz vers 48kHz. */
+#define FX_REVERB_COMB0 1215U
+#define FX_REVERB_COMB1 1293U
+#define FX_REVERB_COMB2 1390U
+#define FX_REVERB_COMB3 1476U
+#define FX_REVERB_COMB4 1548U
+#define FX_REVERB_COMB5 1623U
+#define FX_REVERB_COMB6 1695U
+#define FX_REVERB_COMB7 1761U
+
+#define FX_REVERB_ALLPASS0 605U
+#define FX_REVERB_ALLPASS1 480U
+#define FX_REVERB_ALLPASS2 371U
+#define FX_REVERB_ALLPASS3 245U
+
+static float fx_reverb_comb_buf0[FX_REVERB_COMB0];
+static float fx_reverb_comb_buf1[FX_REVERB_COMB1];
+static float fx_reverb_comb_buf2[FX_REVERB_COMB2];
+static float fx_reverb_comb_buf3[FX_REVERB_COMB3];
+static float fx_reverb_comb_buf4[FX_REVERB_COMB4];
+static float fx_reverb_comb_buf5[FX_REVERB_COMB5];
+static float fx_reverb_comb_buf6[FX_REVERB_COMB6];
+static float fx_reverb_comb_buf7[FX_REVERB_COMB7];
+
+static float fx_reverb_allpass_buf0[FX_REVERB_ALLPASS0];
+static float fx_reverb_allpass_buf1[FX_REVERB_ALLPASS1];
+static float fx_reverb_allpass_buf2[FX_REVERB_ALLPASS2];
+static float fx_reverb_allpass_buf3[FX_REVERB_ALLPASS3];
+
+static float FxComb_Process(FxCombState *c, float input, float feedback, float damp1, float damp2)
+{
+    float output = c->buffer[c->idx];
+    c->filter_store = (output * damp2) + (c->filter_store * damp1);
+    c->buffer[c->idx] = input + (c->filter_store * feedback);
+    c->idx = (c->idx + 1U) % c->size;
+    return output;
+}
+
+static float FxAllpass_Process(FxAllpassState *a, float input, float feedback)
+{
+    float buf_out = a->buffer[a->idx];
+    float output = -input + buf_out;
+    a->buffer[a->idx] = input + buf_out * feedback;
+    a->idx = (a->idx + 1U) % a->size;
+    return output;
+}
+
+void FxReverb_Init(FxReverbState *state, FxReverbParams *params)
+{
+    params->enabled   = false;
+    params->room_size = 0.5f;
+    params->damping   = 0.5f;
+    params->mix       = 0.3f;
+
+    float *comb_buffers[FX_REVERB_NUM_COMBS] = {
+        fx_reverb_comb_buf0, fx_reverb_comb_buf1, fx_reverb_comb_buf2, fx_reverb_comb_buf3,
+        fx_reverb_comb_buf4, fx_reverb_comb_buf5, fx_reverb_comb_buf6, fx_reverb_comb_buf7
+    };
+    uint32_t comb_sizes[FX_REVERB_NUM_COMBS] = {
+        FX_REVERB_COMB0, FX_REVERB_COMB1, FX_REVERB_COMB2, FX_REVERB_COMB3,
+        FX_REVERB_COMB4, FX_REVERB_COMB5, FX_REVERB_COMB6, FX_REVERB_COMB7
+    };
+    for (uint32_t i = 0; i < FX_REVERB_NUM_COMBS; i++)
+    {
+        state->combs[i].buffer = comb_buffers[i];
+        state->combs[i].size = comb_sizes[i];
+        state->combs[i].idx = 0;
+        state->combs[i].filter_store = 0.0f;
+        memset(comb_buffers[i], 0, comb_sizes[i] * sizeof(float));
+    }
+
+    float *allpass_buffers[FX_REVERB_NUM_ALLPASS] = {
+        fx_reverb_allpass_buf0, fx_reverb_allpass_buf1, fx_reverb_allpass_buf2, fx_reverb_allpass_buf3
+    };
+    uint32_t allpass_sizes[FX_REVERB_NUM_ALLPASS] = {
+        FX_REVERB_ALLPASS0, FX_REVERB_ALLPASS1, FX_REVERB_ALLPASS2, FX_REVERB_ALLPASS3
+    };
+    for (uint32_t i = 0; i < FX_REVERB_NUM_ALLPASS; i++)
+    {
+        state->allpass[i].buffer = allpass_buffers[i];
+        state->allpass[i].size = allpass_sizes[i];
+        state->allpass[i].idx = 0;
+        memset(allpass_buffers[i], 0, allpass_sizes[i] * sizeof(float));
+    }
+}
+
+float FxReverb_Process(FxReverbState *state, const FxReverbParams *params, float input)
+{
+    if (!params->enabled)
+    {
+        return input;
+    }
+
+    float feedback = 0.28f + params->room_size * 0.7f;
+    float damp1 = params->damping * 0.4f;
+    float damp2 = 1.0f - damp1;
+
+    float out = 0.0f;
+    for (uint32_t i = 0; i < FX_REVERB_NUM_COMBS; i++)
+    {
+        out += FxComb_Process(&state->combs[i], input, feedback, damp1, damp2);
+    }
+    out /= (float)FX_REVERB_NUM_COMBS;
+
+    for (uint32_t i = 0; i < FX_REVERB_NUM_ALLPASS; i++)
+    {
+        out = FxAllpass_Process(&state->allpass[i], out, 0.5f);
+    }
+
+    return input * (1.0f - params->mix) + out * params->mix;
+}