Update ml_delay.md

Author: marcel-licence

extras/ml_delay.md

@@ -1,7 +1,134 @@
-<h1 align="center">Delay</h1>
-<h3 align="center">A very simple delay</h3>  
+# Delay
+### A very simple delay module
 
-This module provides a delay effect.
-It supports two delay lines for a stereo delay.
-The Delay_Init function needs a buffer and the length for a mono delay.
-For stereo please use Delay_Init2 which needs two buffers.
+This module provides a **mono** or **stereo delay effect**.  
+It supports different audio formats (`int16_t` and `float`) and multiple input/output modes.
+
+---
+
+## Initialization
+
+The delay module requires a buffer (or two for stereo). The buffer length determines the **maximum delay length**.
+
+- For **mono**: `void Delay_Init(int16_t *buffer, uint32_t len);`
+
+- For **stereo**: `void Delay_Init2(int16_t *left, int16_t *right, uint32_t len);`
+
+- `buffer`, `left`, `right`: pointers to delay line buffers.  
+- `len`: number of samples per buffer. This defines the maximum delay length.  
+- Maximum delay in time = `len / SAMPLE_RATE` seconds.  
+
+To reset the delay state:
+```c
+void Delay_Reset(void);
+```
+
+---
+
+## Processing
+
+The delay supports multiple processing functions depending on the input/output format and mode.  
+
+### Mono
+```c
+// Mono in/out
+void Delay_Process_Buff(float *signal_l, int buffLen);
+void Delay_Process_Buff(int16_t *signal_l, int buffLen);
+```
+
+### Mono → Stereo
+```c
+// Mono input, stereo output
+void Delay_Process_Buff(float *in, float *left, float *right, int buffLen);
+void Delay_Process_Buff(int16_t *in, int16_t *left, int16_t *right, int buffLen);
+```
+
+### Stereo
+```c
+// Stereo input/output
+void Delay_Process_Buff(float *in_l, float *in_r, float *out_l, float *out_r, int buffLen);
+void Delay_Process_Buff(int16_t *in_l, int16_t *in_r, int16_t *out_l, int16_t *out_r, int buffLen);
+void Delay_Process_Buff2(float *signal_l, float *signal_r, int buffLen); // in/out inplace
+```
+
+- `buffLen`: number of samples to process per call.  
+- Use the function variant matching your signal format (`float` or `int16_t`).  
+
+---
+
+## Parameters
+
+The module provides several parameter setters.  
+
+### Input Level
+```c
+void Delay_SetInputLevel(uint8_t unused, float value);
+void Delay_SetInputLevel(uint8_t unused, uint8_t value);
+```
+
+- `float`: range **0.0 … 1.0** (linear gain).  
+- `uint8_t`: range **0 … 127** (MIDI-style scaling).  
+
+### Feedback
+```c
+void Delay_SetFeedback(uint8_t unused, float value);
+void Delay_SetFeedback(uint8_t unused, uint8_t value);
+```
+
+- Controls how much delayed signal is fed back into the input.  
+- Same ranges as above.
+
+### Output Level
+```c
+void Delay_SetOutputLevel(uint8_t unused, float value);
+void Delay_SetOutputLevel(uint8_t unused, uint8_t value);
+```
+
+### Delay Length
+```c
+void Delay_SetLength(uint8_t unused, float value);
+void Delay_SetLength(uint8_t unused, uint32_t value);
+```
+
+- `float`: **0.0 … 1.0** → percentage of max delay (`len`).  
+- `uint32_t`: absolute delay length in samples.  
+
+### Stereo Shift
+```c
+void Delay_SetShift(uint8_t unused, float value);
+```
+
+- Used only in **stereo mode**.  
+- Shifts one channel relative to the other.  
+- Range: **0.0 … 1.0**.
+
+---
+
+## Examples
+
+### Mono Delay
+```c
+#define BUFFER_LEN 48000
+static int16_t delayBuffer[BUFFER_LEN];
+
+Delay_Init(delayBuffer, BUFFER_LEN);
+Delay_SetFeedback(0, 0.5f);       // 50% feedback
+Delay_SetLength(0, 0.25f);        // 25% of buffer length
+Delay_SetOutputLevel(0, 1.0f);    // full output
+
+Delay_Process_Buff(inputBuffer, 256);
+```
+
+### Stereo Delay
+```c
+#define BUFFER_LEN 48000
+static int16_t delayBufferL[BUFFER_LEN];
+static int16_t delayBufferR[BUFFER_LEN];
+
+Delay_Init2(delayBufferL, delayBufferR, BUFFER_LEN);
+Delay_SetFeedback(0, 64);         // MIDI style (64/127 ~ 0.5)
+Delay_SetLength(0, 24000);        // 24000 samples delay
+Delay_SetShift(0, 0.1f);          // slight stereo shift
+
+Delay_Process_Buff(inputL, inputR, outputL, outputR, 256);
+```