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libraries/audio-tools/examples/examples-dsp/examples-stk/streams-stk_synth-audiokit/README.md

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+# Implementing a Synthesizer using the STK Framwork
+
+We can use the STK framework to implement a Synthesizer which receives Midi Messages and translates them 
+into sound. Here we use a Clarinet...
+
+We demo how to use the Stream output classes provided by STK.
+
+For [further info see my blog](https://www.pschatzmann.ch/home/2021/12/21/ai-thinker-audiokit-a-simply-synthesizer-with-stk/)
+
+### Dependencies
+
+- https://github.com/pschatzmann/arduino-audio-tools
+- https://github.com/pschatzmann/arduino-audio-driver
+- https://github.com/pschatzmann/arduino-midi
+- https://github.com/pschatzmann/Arduino-STK

libraries/audio-tools/examples/examples-dsp/examples-stk/streams-stk_synth-audiokit/streams-stk_synth-audiokit.ino

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+/**
+ * @file streams-synthstk-audiokit.ino
+ * @brief see https://www.pschatzmann.ch/home/2021/12/17/ai-thinker-audiokit-a-simple-synthesizer-with-stk/
+ * @author Phil Schatzmann
+ * @copyright Copyright (c) 2021
+ */
+#include "AudioTools.h"
+#include "AudioTools/AudioLibs/AudioBoardStream.h" // install https://github.com/pschatzmann/arduino-audio-driver
+#include "StkAll.h" // install https://github.com/pschatzmann/Arduino-STK
+
+AudioBoardStream kit(AudioKitEs8388V1);
+Clarinet clarinet(440);
+Voicer voicer;
+ArdStreamOut output(&kit);
+float noteAmplitude = 128;
+int group = 0;
+
+void actionKeyOn(bool active, int pin, void* ptr){
+  float note = *((float*)ptr);
+  voicer.noteOn(note, noteAmplitude, group);
+}
+
+void actionKeyOff(bool active, int pin, void* ptr){
+  float note = *((float*)ptr);
+  voicer.noteOff(note, noteAmplitude, group);
+}
+
+// We want to play some notes on the AudioKit keys 
+void setupActions(){
+  // assign buttons to notes
+  auto act_low = AudioActions::ActiveLow;
+  static int note[] = {48,50,52,53,55,57}; // midi keys
+  kit.audioActions().add(kit.getKey(1), actionKeyOn, actionKeyOff, act_low, &(note[0])); // C3
+  kit.audioActions().add(kit.getKey(2), actionKeyOn, actionKeyOff, act_low, &(note[1])); // D3
+  kit.audioActions().add(kit.getKey(3), actionKeyOn, actionKeyOff, act_low, &(note[2])); // E3
+  kit.audioActions().add(kit.getKey(4), actionKeyOn, actionKeyOff, act_low, &(note[3])); // F3
+  kit.audioActions().add(kit.getKey(5), actionKeyOn, actionKeyOff, act_low, &(note[4])); // G3
+  kit.audioActions().add(kit.getKey(6), actionKeyOn, actionKeyOff, act_low, &(note[5])); // A3
+}
+
+void setup() {
+  Serial.begin(115200);
+  AudioLogger::instance().begin(Serial,AudioLogger::Warning);
+
+  voicer.addInstrument(&clarinet, group);
+
+  // define data format
+  auto cfg = kit.defaultConfig(TX_MODE);
+  cfg.channels = 1;
+  cfg.bits_per_sample = 16;
+  cfg.sample_rate = Stk::sampleRate();
+  cfg.sd_active = false;
+  kit.begin(cfg);
+
+  // play notes with keys
+  setupActions();
+
+}
+
+void loop() {
+   for (int j=0;j<1024;j++) {
+      output.tick( voicer.tick() );
+   }
+   kit.processActions();
+}