fix scope triggering

src/synth/AudioEngine.h

@@ -47,7 +47,7 @@ private:
     RtAudio audio_{AUDIO_API}; // audio device
     // TODO: id like a yml config file or something for these
     uint32_t sampleRate_ = 44100;
-    uint32_t bufferFrames_ = 256; // time per buffer = BF/SR (256/44100 = 5.8ms)
+    uint32_t bufferFrames_ = 512; // time per buffer = BF/SR (256/44100 = 5.8ms)
     uint32_t channels_ = 2; // stereo
 
 };

src/synth/Synth.cpp

@@ -76,6 +76,7 @@ void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
 
     float sampleOut = 0.0f;
     bool triggered = false;
+    bool once = false;
 
     for (uint32_t i = 0; i < nFrames; i++) {
 
@@ -88,10 +89,24 @@ void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
             params[i] = params_[i].current;
         } // maybe take this outside the loop if performance is an issue
 
+        // find the lowest voice for scope triggering
+        int lowestVoice = 0;
+        float lowestFreq = 100000.0f;
+        for(int i = 0; i < voices_.size(); i++) {
+            if(!voices_[i].isActive()) continue;
+            float currentFreq = voices_[i].frequency();
+            if(currentFreq < lowestFreq) {
+                lowestVoice = i;
+                lowestFreq = currentFreq;
+            }
+        }
+
         // foreach voice, process...
         float mix = 0.0f;
-        for(Voice& v : voices_) {
-            mix += v.process(params, triggered);
+        for(int i = 0; i < voices_.size(); i++) {
+            bool temp = false;
+            mix += voices_[i].process(params, temp);
+            if(i == lowestVoice) triggered = temp;
         }
         mix /= 4.0f; // for number of voices to prevent clipping
         mix = tanh(mix); // really prevents clipping
@@ -109,15 +124,10 @@ void Synth::process(float* out, uint32_t nFrames, uint32_t sampleRate) {
         }
 
         // triggering business
-        // TODO: get trigger info from voice (lowest frequency voice)
-        float phase_ = 0.0f;
-        if (phase_ > 2.0f * M_PI) {
-            phase_ -= 2.0f * M_PI;
-            if(!triggered) {
-                scope_->setTrigger(i); // this is where we consider the start of a waveform
-                triggered = true;
-                // TODO: investigate triggering accross buffers when a single wave period transcends a single audio buffer
-            }
+        if(triggered && (!once)) {
+            scope_->setTrigger(i); // this is where we consider the start of a waveform
+            once = true;
+            // TODO: investigate triggering accross buffers when a single wave period transcends a single audio buffer
         }
     }
 

src/synth/Voice.cpp

@@ -125,6 +125,7 @@ float Voice::process(float* params, bool& scopeTrigger) {
     // state tracking, may keep this here even if oscillators store their own phase because it might help with scope triggering
     phase_ += phaseInc;
     if (phase_ > 2.0f * M_PI) {
+        scopeTrigger = true;
         phase_ -= 2.0f * M_PI;
     }
 

src/synth/Voice.h

@@ -40,6 +40,7 @@ public:
     float process(float* params, bool& scopeTrigger);
 
     uint8_t note() { return note_; }
+    float frequency() { return frequency_; }
 
 private: