Create ml_vibrato.md

Author: marcel-licence

extras/ml_vibrato.md

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+# Vibrato
+### A simple vibrato effect
+
+The `ML_Vibrato` class implements a vibrato effect using a circular buffer and modulation input.  
+It supports standard and high-quality processing modes.
+
+---
+
+## Constants
+
+```c
+#define VIBRATO_BUFFER_SIZE    1024
+```
+
+- Size of the internal circular buffer used for delay modulation.  
+- Determines maximum vibrato depth (in samples).  
+
+---
+
+## Class Interface
+
+```c++
+class ML_Vibrato
+{
+public:
+    ML_Vibrato(float sample_rate);
+    ~ML_Vibrato() {};
+
+    void Process(const float *in, const float *mod_in, float *out, uint32_t count);
+    void ProcessHQ(const float *in, const float *mod_in, float *out, uint32_t count);
+
+    void setDepth(float depth);
+    void setIntensity(float intensity);
+
+private:
+    void ModMultiplierUpdate();
+
+    float sample_rate;
+    float depth;
+    float depthInv;
+    float buffer[VIBRATO_BUFFER_SIZE];
+    float mod_multiplier;
+    float mod_multiplier_curr;
+    int32_t inCnt;
+};
+```
+
+---
+
+## Constructor & Destructor
+
+```c++
+ML_Vibrato(float sample_rate);
+~ML_Vibrato();
+```
+
+- `sample_rate`: system sampling rate in Hz.  
+- Destructor does nothing special.  
+
+---
+
+## Processing
+
+### Standard Processing
+```c++
+void Process(const float *in, const float *mod_in, float *out, uint32_t count);
+```
+
+- `in`: pointer to input buffer.  
+- `mod_in`: pointer to modulation buffer (typically LFO).  
+- `out`: pointer to output buffer.  
+- `count`: number of samples to process.  
+
+### High-Quality Processing
+```c++
+void ProcessHQ(const float *in, const float *mod_in, float *out, uint32_t count);
+```
+
+- Similar to `Process()` but uses a higher-quality interpolation method for smoother vibrato.  
+
+---
+
+## Parameters
+
+### Depth
+```c++
+void setDepth(float depth);
+```
+- Sets vibrato depth in **samples**.  
+- Maximum is limited by `VIBRATO_BUFFER_SIZE`.  
+
+### Intensity
+```c++
+void setIntensity(float intensity);
+```
+- Controls modulation intensity (scaling applied to `mod_in`).  
+
+---
+
+## Private Helper
+
+```c++
+void ModMultiplierUpdate();
+```
+- Updates modulation multiplier values internally.  
+
+---
+
+## Example Usage
+
+```c++
+#include "ML_Vibrato.h"
+
+#define BLOCK_SIZE 256
+
+ML_Vibrato vibrato(48000.0f);
+
+float in[BLOCK_SIZE];
+float mod[BLOCK_SIZE];  // typically filled with LFO samples
+float out[BLOCK_SIZE];
+
+void audioCallback()
+{
+    // set parameters
+    vibrato.setDepth(64.0f);       // depth in samples
+    vibrato.setIntensity(0.8f);    // modulation intensity
+
+    // process audio
+    vibrato.Process(in, mod, out, BLOCK_SIZE);
+}
+```