Increase granular speed range, change public function to setSpeed()

effect_granular.cpp

@@ -31,7 +31,7 @@ void AudioEffectGranular::begin(int16_t *sample_bank_def, int16_t max_len_def)
 	read_head = 0;
 	write_head = 0;
 	prev_input = 0;
-	playpack_rate = 512;
+	playpack_rate = 65536;
 	accumulator = 0;
 	allow_len_change = true;
 	sample_loaded = false;
@@ -51,10 +51,6 @@ void AudioEffectGranular::beginFreeze_int(int grain_samples)
 	write_en = false;
 	sample_req = true;
 	__enable_irq();
-	Serial.print("in = ");
-	Serial.print(grain_samples);
-	Serial.print(", freeze len = ");
-	Serial.println(freeze_len);
 }
 
 void AudioEffectGranular::beginPitchShift_int(int grain_samples)
@@ -79,11 +75,6 @@ void AudioEffectGranular::stop()
 	allow_len_change = true;
 }
 
-void AudioEffectGranular::rate(int16_t playpack_rate_def)
-{
-	playpack_rate = playpack_rate_def;
-}
-
 void AudioEffectGranular::update(void)
 {
 	audio_block_t *block;
@@ -102,7 +93,7 @@ void AudioEffectGranular::update(void)
 		prev_input = block->data[AUDIO_BLOCK_SAMPLES-1];
 	}
 	else if (grain_mode == 1) {
-		//when activated the last
+		// Freeze - sample 1 grain, then repeatedly play it back
 		for (int j = 0; j < AUDIO_BLOCK_SAMPLES; j++) {
 			if (sample_req) {
 				// only begin capture on zero cross
@@ -113,7 +104,6 @@ void AudioEffectGranular::update(void)
 					write_head = 0;
 					read_head = 0;
 					sample_req = false;
-					Serial.println("begin freeze capture");
 				} else {
 					prev_input = current_input;
 				}
@@ -125,13 +115,12 @@ void AudioEffectGranular::update(void)
 				}
 				if (write_head >= max_sample_len) {
 					write_en = false;
-					Serial.println("end freeze capture");
 				}
 			}
 			if (sample_loaded) {
 				if (playpack_rate >= 0) {
 					accumulator += playpack_rate;
-					read_head = accumulator >> 9;
+					read_head = accumulator >> 16;
 				}
 				if (read_head >= freeze_len) {
 					accumulator = 0;
@@ -206,7 +195,7 @@ void AudioEffectGranular::update(void)
 			}
 
 			accumulator += playpack_rate;
-			read_head = (accumulator >> 9);
+			read_head = (accumulator >> 16);
 
 			if (read_head >= glitch_len) {
 				read_head -= glitch_len;

effect_granular.h

@@ -28,7 +28,11 @@ class AudioEffectGranular : public AudioStream
 public:
 	AudioEffectGranular(void): AudioStream(1,inputQueueArray) { }
 	void begin(int16_t *sample_bank_def, int16_t max_len_def);
-	void rate(int16_t playpack_rate_def);
+	void setSpeed(float ratio) {
+		if (ratio < 0.125) ratio = 0.125;
+		else if (ratio > 8.0) ratio = 8.0;
+		playpack_rate = ratio * 65536.0 + 0.499;
+	}
 	void beginFreeze(float grain_length) {
 		if (grain_length <= 0.0) return;
 		beginFreeze_int(grain_length * (AUDIO_SAMPLE_RATE_EXACT * 0.001) + 0.5);
@@ -44,13 +48,13 @@ private:
 	void beginPitchShift_int(int grain_samples);
 	audio_block_t *inputQueueArray[1];
 	int16_t *sample_bank;
+	uint32_t playpack_rate;
+	uint32_t accumulator;
 	int16_t max_sample_len;
 	int16_t write_head;
 	int16_t read_head;
 	int16_t grain_mode;
 	int16_t freeze_len;
-	int16_t playpack_rate;
-	int32_t accumulator;
 	int16_t prev_input;
 	int16_t glitch_len;
 	bool allow_len_change;

examples/Effects/Granular/Granular.ino

@@ -1,3 +1,15 @@
+// Granular Effect Example - Pitch shift or freeze sound
+//
+// This example is meant to be used with 3 buttons (pin 0,
+// 1, 2) and 2 knobs (pins 16/A2, 17/A3), which are present
+// on the audio tutorial kit.
+//   https://www.pjrc.com/store/audio_tutorial_kit.html
+//
+// Data files to put on your SD card can be downloaded here:
+//   http://www.pjrc.com/teensy/td_libs_AudioDataFiles.html
+//
+// This example code is in the public domain.
+
 #include <Audio.h>
 #include <Wire.h>
 #include <SPI.h>
@@ -91,22 +103,33 @@ void loop() {
   float knobA2 = (float)analogRead(A2) / 1023.0;
   float knobA3 = (float)analogRead(A3) / 1023.0;
 
+  // Button 0 starts Freeze effect
   if (button0.fallingEdge()) {
-    // Button 0 starts Freeze effect
-    granular1.beginFreeze(knobA3 * 290.0);
+    float msec = 100.0 + (knobA3 * 190.0);
+    granular1.beginFreeze(msec);
+    Serial.print("Begin granular freeze using ");
+    Serial.print(msec);
+    Serial.println(" grains");
   }
   if (button0.risingEdge()) {
     granular1.stop();
   }
 
+  // Button 1 starts Pitch Shift effect
   if (button1.fallingEdge()) {
-    // Button 1 starts Pitch Shift effect
-    granular1.beginPitchShift(knobA3 * 100.0);
+    float msec = 25.0 + (knobA3 * 75.0);
+    granular1.beginPitchShift(msec);
+    Serial.print("Begin granular pitch phift using ");
+    Serial.print(msec);
+    Serial.println(" grains");
   }
   if (button1.risingEdge()) {
     granular1.stop();
   }
 
-  // continuously adjust pitch bend
-  granular1.rate(knobA2 * 1023.0);
+  // Continuously adjust the speed, based on the A3 pot
+  float ratio;
+  ratio = powf(2.0, knobA2 * 2.0 - 1.0); // 0.5 to 2.0
+  //ratio = powf(2.0, knobA2 * 6.0 - 3.0); // 0.125 to 8.0 -- uncomment for far too much range!
+  granular1.setSpeed(ratio);
 }

keywords.txt

@@ -93,6 +93,9 @@ disableDither	KEYWORD2
 reverbTime	KEYWORD2
 roomsize	KEYWORD2
 damping	KEYWORD2
+setSpeed	KEYWORD2
+beginFreeze	KEYWORD2
+beginPitchShift	KEYWORD2
 frequency	KEYWORD2
 phase	KEYWORD2
 amplitude	KEYWORD2