Fixed initial modulated delay offset when loading a sound.

Removed modulated_delay internal feedback loop and added an "external" feedback lopp with a mixer.

MicroMDAEPiano.ino

@@ -54,6 +54,8 @@ AudioMixer4              mixer_l;
 AudioAmplifier           volume_r;
 AudioAmplifier           volume_l;
 AudioAmplifier           inverter;
+AudioMixer4              modchorus_fbk_mixer_r;
+AudioMixer4              modchorus_fbk_mixer_l;
 AudioEffectModulatedDelay   modchorus_r;
 AudioEffectModulatedDelay   modchorus_l;
 AudioSynthWaveform       modulator;
@@ -61,13 +63,17 @@ AudioConnection          patchCord0(queue_r, peak_r);
 AudioConnection          patchCord1(queue_l, peak_l);
 AudioConnection          patchCord2(queue_r, freeverb_r);
 AudioConnection          patchCord3(queue_l, freeverb_l);
-AudioConnection          patchCord4(queue_r, 0, modchorus_r, 0);
+AudioConnection          patchCord4(queue_r, 0, modchorus_fbk_mixer_r, 0);
-AudioConnection          patchCord5(queue_l, 0, modchorus_l, 0);
+AudioConnection          patchCord5(queue_l, 0, modchorus_fbk_mixer_l, 0);
-AudioConnection          patchCord8(modulator, 0, modchorus_r, 1);
+AudioConnection          patchCord6(modchorus_fbk_mixer_r, 0, modchorus_r, 0);
-AudioConnection          patchCord9(modulator, inverter);
+AudioConnection          patchCord7(modchorus_fbk_mixer_l, 0, modchorus_l, 0);
-AudioConnection          patchCord10(inverter, 0, modchorus_l, 1);
+AudioConnection          patchCord8(modchorus_r, 0, modchorus_r, 1);
-AudioConnection          patchCord11(queue_r, 0, mixer_r, 0);
+AudioConnection          patchCord9(modchorus_l, 0, modchorus_l, 1);
-AudioConnection          patchCord12(queue_l, 0, mixer_l, 0);
+AudioConnection          patchCord10(modulator, 0, modchorus_r, 1);
+AudioConnection          patchCord11(modulator, inverter);
+AudioConnection          patchCord12(inverter, 0, modchorus_l, 1);
+AudioConnection          patchCord13(queue_r, 0, mixer_r, 0);
+AudioConnection          patchCord14(queue_l, 0, mixer_l, 0);
 AudioConnection          patchCord15(modchorus_r, 0, mixer_r, 2);
 AudioConnection          patchCord16(modchorus_l, 0, mixer_l, 2);
 AudioConnection          patchCord17(freeverb_r, 0, mixer_r, 1);
@@ -235,11 +241,19 @@ void setup()
   modulator.phase(0);
   modulator.amplitude(1.0);
   modulator.offset(0.0);
+#ifdef MOD_STEREO
   inverter.gain(-1.0); // change phase for second modulated delay (faked stereo mode)
+#else
+  inverter.gain(1.0);
+#endif
   modchorus_r.offset(15.0);
   modchorus_l.offset(15.0);
-  modchorus_r.feedback(0.25);
+  //modchorus_r.feedback(0.25);
-  modchorus_l.feedback(0.25);
+  //modchorus_l.feedback(0.25);
+  modchorus_fbk_mixer_r.gain(0, 0.75);
+  modchorus_fbk_mixer_l.gain(0, 0.75);
+  modchorus_fbk_mixer_r.gain(1, 0.25);
+  modchorus_fbk_mixer_l.gain(1, 0.25);
 
   // internal mixing of original signal(0), reverb(1) and chorus(2)
   mixer_r.gain(VOL_MAIN, 0.5);

UI.hpp

@@ -126,6 +126,8 @@ extern AudioEffectFreeverb freeverb_l;
 extern AudioSynthWaveform modulator;
 extern AudioEffectModulatedDelay modchorus_r;
 extern AudioEffectModulatedDelay modchorus_l;
+extern AudioMixer4 modchorus_fbk_mixer_r;
+extern AudioMixer4 modchorus_fbk_mixer_l;
 extern AudioMixer4 mixer_r;
 extern AudioMixer4 mixer_l;
 extern AudioAmplifier volume_r;
@@ -2206,8 +2208,13 @@ void set_chorus_feedback(uint8_t value)
   Serial.print(F("Set CHORUS_FEEDBACK "));
   Serial.println(value);
 #endif
-  modchorus_r.feedback(mapfloat(float(value), ENC_CHORUS_FEEDBACK_MIN, ENC_CHORUS_FEEDBACK_MAX, 0.0, 1.0));
+  //modchorus_r.feedback(mapfloat(float(value), ENC_CHORUS_FEEDBACK_MIN, ENC_CHORUS_FEEDBACK_MAX, 0.0, 1.0));
-  modchorus_l.feedback(mapfloat(float(value), ENC_CHORUS_FEEDBACK_MIN, ENC_CHORUS_FEEDBACK_MAX, 0.0, 1.0));
+  //modchorus_l.feedback(mapfloat(float(value), ENC_CHORUS_FEEDBACK_MIN, ENC_CHORUS_FEEDBACK_MAX, 0.0, 1.0));
+  float tmp = mapfloat(float(value), ENC_CHORUS_FEEDBACK_MIN, ENC_CHORUS_FEEDBACK_MAX, 0.0, 0.5);
+  modchorus_fbk_mixer_r.gain(0, 1.0 - tmp);
+  modchorus_fbk_mixer_l.gain(0, 1.0 - tmp);
+  modchorus_fbk_mixer_r.gain(1, tmp);
+  modchorus_fbk_mixer_l.gain(1, tmp);
   configuration.chorus_feedback = value;
 }
 
@@ -2630,7 +2637,7 @@ void handle_ui(void)
           if (encoder_tmp != encoder_value[RIGHT_ENCODER])
           {
             // value up/down
-            set_chorus_delay(encoder_tmp);
+            set_chorus_delay(encoder_tmp / 10);
             menu_system.update();
           }
         }

config.h

@@ -30,6 +30,9 @@
 // ATTENTION! For better latency you have to redefine AUDIO_BLOCK_SAMPLES from
 // 128 to 64 in <ARDUINO-IDE-DIR>/cores/teensy3/AudioStream.h
 
+// arecord -f cd -Dhw:1,0 /tmp/bla.wav
+// aplaymidi -p 20:0 test.mid 
+
 //*************************************************************************************************
 //* DEVICE SETTINGS
 //*************************************************************************************************
@@ -57,6 +60,7 @@
 // CHORUS parameters
 #define CHORUS_DELAY_LENGTH_SAMPLES (16*AUDIO_BLOCK_SAMPLES) // one AUDIO_BLOCK_SAMPLES = 2.902ms
 #define WAVEFORM_MOD WAVEFORM_TRIANGLE // WAVEFORM_SINE WAVEFORM_TRIANGLE WAVEFORM_SAWTOOTH WAVEFORM_SAWTOOTH_REVERSE
+//#define MOD_STEREO 1
 //*************************************************************************************************
 //* DEBUG OUTPUT SETTINGS
 //*************************************************************************************************

effect_modulated_delay.cpp

@@ -51,8 +51,6 @@ boolean AudioEffectModulatedDelay::begin(short *delayline, int d_length)
   _delay_length = 0;
   _delay_offset = 0.0;
   _cb_index = 0;
-  _feedback = 0.0;
-  _feedback_value = 0;
 
   if (delayline == NULL) {
     return (false);
@@ -82,16 +80,6 @@ float AudioEffectModulatedDelay::offset(float offset_value) // in ms
   return (floor(offset_frames / AUDIO_SAMPLE_RATE * 1000));
 }
 
-void AudioEffectModulatedDelay::feedback(float feedback_level)
-{
-  if (feedback_level < 0.0)
-    feedback_level = 0.0;
-  else if (feedback_level > 1.0)
-    feedback_level = 1.0;
-
-  _feedback = feedback_level / 2;
-}
-
 void AudioEffectModulatedDelay::update(void)
 {
   audio_block_t *block;
@@ -122,7 +110,7 @@ void AudioEffectModulatedDelay::update(void)
       // write data into circular buffer (delayline)
       if (_cb_index >= _delay_length)
         _cb_index = 0;
-      _delayline[_cb_index] = (*bp * (1.0 - _feedback)) + (_feedback_value * _feedback);
+      _delayline[_cb_index] = *bp;
 
       // calculate the modulation-index as a floating point number for interpolation
       mod_index = *mp * MODULATION_MAX_FACTOR * _delay_length;

effect_modulated_delay.h

@@ -45,7 +45,6 @@ class AudioEffectModulatedDelay :
     boolean begin(short *delayline, int delay_length);
     virtual void update(void);
     virtual float offset(float offset_value);
-    virtual void feedback(float feedback_value);
 
   private:
     void set_modulator_filter_coeffs(void);
@@ -54,8 +53,6 @@ class AudioEffectModulatedDelay :
     uint16_t _cb_index;   // current write pointer of the circular buffer
     uint16_t _delay_offset; // number of samples for the read offset of the modulation inside the circular buffer
     uint16_t _delay_length; // calculated number of samples of the delay
-    float32_t _feedback;
-    int16_t _feedback_value;
     int16_t cb_mod_index; // current read pointer with modulation for the circular buffer
 };