Optimizations 1

AudioThread.cpp

@@ -12,8 +12,8 @@ const int I2S_LRC_PIN  = 10; // Left-Right Clock (GP10)
 const int I2S_DOUT_PIN = 11; // Data Out (GP11)
 
 // Audio parameters
-const int SAMPLE_RATE = 44100;
-const int16_t AMPLITUDE = 16383; // Use a lower amplitude to avoid clipping (max is 32767 for 16-bit)
+const int SAMPLE_RATE = 44100 / 2;
+const int16_t AMPLITUDE = 16383 / 2; // Use a lower amplitude to avoid clipping (max is 32767 for 16-bit)
 
 // Create an I2S output object
 I2S i2s(OUTPUT);
@@ -43,6 +43,7 @@ void setupAudio() {
   
   // Initialize the portable synth engine
   globalSynth = new SynthEngine(SAMPLE_RATE);
+  globalSynth->loadPreset(2);
 }
 
 void loopAudio() {
@@ -51,27 +52,56 @@ void loopAudio() {
   // Every 500ms, pick a new random note to play
   if (now - lastNoteChangeTime > 500) {
     lastNoteChangeTime = now;
-    int noteIndex = random(0, SCALES[currentScaleIndex].numNotes);
+    int noteIndex = random(0, SCALES[currentScaleIndex].numNotes + 2);
     
-    // Calculate frequency based on key, scale, and octave
-    const float baseFrequency = 261.63f; // C4
-    float keyFrequency = baseFrequency * pow(2.0f, currentKeyIndex / 12.0f);
-    int semitoneOffset = SCALES[currentScaleIndex].semitones[noteIndex];
-    currentFrequency = keyFrequency * pow(2.0f, semitoneOffset / 12.0f);
+    bool rest = noteIndex >= SCALES[currentScaleIndex].numNotes;
+    if (!rest) {
+      // Calculate frequency based on key, scale, and octave
+      const float baseFrequency = 261.63f; // C4
+      float keyFrequency = baseFrequency * pow(2.0f, currentKeyIndex / 12.0f);
+      int semitoneOffset = SCALES[currentScaleIndex].semitones[noteIndex];
+      currentFrequency = keyFrequency * pow(2.0f, semitoneOffset / 12.0f);
+    } else {
+      currentFrequency = 0;
+    }
 
     if (globalSynth) {
-        globalSynth->setFrequency(currentFrequency);
-        globalSynth->setGate(true); // Trigger envelope
+        globalSynth->setFrequency(currentFrequency > 0 ? currentFrequency : 440.0f);
+        globalSynth->setGate(!rest); // Trigger envelope
     }
-    Serial.println("Playing note: " + String(currentFrequency) + " Hz");
+  }
+
+  const int BATCH_SIZE = 16;
+
+  // Ensure we don't generate samples faster than the I2S can consume them.
+  // We write 2 samples (Left + Right) for every 1 synth sample.
+  if (i2s.availableForWrite() < BATCH_SIZE * 2) {
+      return;
   }
 
   // Process a small batch of samples
-  int16_t samples[32];
-  if (globalSynth) globalSynth->process(samples, 32);
-  else memset(samples, 0, sizeof(samples));
+  static int16_t samples[BATCH_SIZE];
 
-  for (int i = 0; i < 32; ++i) {
+  // Generate sound samples
+  if (globalSynth) {
+    // using synth engine
+    globalSynth->process(samples, BATCH_SIZE);
+  } else {
+    // using fallback sawtooth
+    for (int i = 0; i < BATCH_SIZE; ++i) {
+        if (currentFrequency > 0) {
+            //samples[i] = (int16_t)(sin(phase) * AMPLITUDE);
+            phase += 2.0 * M_PI * currentFrequency / SAMPLE_RATE;
+            if (phase >= 2.0 * M_PI) phase -= 2.0 * M_PI;
+            samples[i] = phase * 0.1f * AMPLITUDE;
+        } else {
+            samples[i] = 0;
+        }
+    }
+  }
+
+  // write out stereo samples
+  for (int i = 0; i < BATCH_SIZE; ++i) {
       i2s.write(samples[i]);
       i2s.write(samples[i]);
   }