Don't update render observer when sequence changes.

Author: aure

Sources/AudioKitEX/Sequencing/SequencerTrack.swift

@@ -10,7 +10,7 @@ import AudioKit
 open class SequencerTrack {
 
     /// Node sequencer sends data to
-    public var targetNode: Node?
+    public var targetNode: Node? { didSet { addRenderObserver() }}
 
     /// Length of the track in beats
     public var length: Double = 4 { didSet { updateSequence() }}
@@ -123,7 +123,6 @@ open class SequencerTrack {
     }
 
     private var renderObserverToken: Int?
-    public var renderObserver: AURenderObserver?
 
     private func updateSequence() {
         guard let block = targetNode?.avAudioNode.auAudioUnit.scheduleMIDIEventBlock else {
@@ -139,19 +138,25 @@ open class SequencerTrack {
 
         let orderedEvents = sequence.beatTimeOrderedEvents()
         orderedEvents.withUnsafeBufferPointer { (eventsPtr: UnsafeBufferPointer<SequenceEvent>) -> Void in
-            guard let observer = akSequencerEngineUpdateSequence(engine,
-                                                                 eventsPtr.baseAddress,
-                                                                 orderedEvents.count,
-                                                                 settings,
-                                                                 Settings.sampleRate,
-                                                                 block) else { return }
 
-            guard let auAudioUnit = targetNode?.avAudioNode.auAudioUnit else { return }
+            akSequencerEngineUpdateSequence(engine,
+                                            eventsPtr.baseAddress,
+                                            orderedEvents.count,
+                                            settings,
+                                            Settings.sampleRate,
+                                            block)
 
-            renderObserver = observer
-            if renderObserverToken == nil {
-                renderObserverToken = auAudioUnit.token(byAddingRenderObserver: observer)
-            }
+
+        }
+
+        addRenderObserver()
+    }
+
+    private func addRenderObserver() {
+        if renderObserverToken == nil {
+            guard let observer = akSequencerGetRenderObserver(engine) else { return }
+            guard let auAudioUnit = targetNode?.avAudioNode.auAudioUnit else { return }
+            renderObserverToken = auAudioUnit.token(byAddingRenderObserver: observer)
         }
     }
 }

Sources/CAudioKitEX/Sequencing/SequencerEngine.mm

@@ -219,27 +219,29 @@ void akSequencerEngineRelease(SequencerEngineRef engine) {
 }
 
 /// Updates the sequence and returns a new render observer.
-AURenderObserver akSequencerEngineUpdateSequence(SequencerEngineRef engine,
-                                                 const SequenceEvent* eventsPtr,
-                                                 size_t eventCount,
-                                                 SequenceSettings settings,
-                                                 double sampleRate,
-                                                 AUScheduleMIDIEventBlock block) {
-
-    // impl is captured in the render observer block.
-    auto impl = engine->impl;
-
+void akSequencerEngineUpdateSequence(SequencerEngineRef engine,
+                                     const SequenceEvent* eventsPtr,
+                                     size_t eventCount,
+                                     SequenceSettings settings,
+                                     double sampleRate,
+                                     AUScheduleMIDIEventBlock block) {
     auto data = new SequencerData;
     data->settings = settings;
     data->sampleRate = sampleRate;
     data->midiBlock = block;
     data->events = {eventsPtr, eventsPtr+eventCount};
-    impl->data.set(data);
+    engine->impl->data.set(data);
+}
+
+AURenderObserver akSequencerGetRenderObserver(SequencerEngineRef engine) {
+
+    // impl is captured in the render observer block.
+    auto impl = engine->impl;
 
     return ^void(AudioUnitRenderActionFlags actionFlags,
-                 const AudioTimeStamp *timestamp,
-                 AUAudioFrameCount frameCount,
-                 NSInteger outputBusNumber)
+                     const AudioTimeStamp *timestamp,
+                     AUAudioFrameCount frameCount,
+                     NSInteger outputBusNumber)
     {
         if (actionFlags != kAudioUnitRenderAction_PreRender) return;
         impl->process(frameCount);

Sources/CAudioKitEX/include/SequencerEngine.h

@@ -38,13 +38,16 @@ SequencerEngineRef akSequencerEngineCreate(void);
 /// Release ownership of the sequencer. Sequencer is deallocated when no render observers are live.
 void akSequencerEngineRelease(SequencerEngineRef engine);
 
-/// Updates the sequence and returns a new render observer.
-AURenderObserver akSequencerEngineUpdateSequence(SequencerEngineRef engine,
-                                                        const SequenceEvent* events,
-                                                        size_t eventCount,
-                                                        SequenceSettings settings,
-                                                        double sampleRate,
-                                                        AUScheduleMIDIEventBlock block);
+/// Updates the sequence atomically.
+void akSequencerEngineUpdateSequence(SequencerEngineRef engine,
+                                     const SequenceEvent* events,
+                                     size_t eventCount,
+                                     SequenceSettings settings,
+                                     double sampleRate,
+                                     AUScheduleMIDIEventBlock block);
+
+/// Returns function to be called on audio thread.
+AURenderObserver akSequencerGetRenderObserver(SequencerEngineRef engine);
 
 /// Returns the sequencer playhead position in beats.
 double akSequencerEngineGetPosition(SequencerEngineRef engine);

Tests/AudioKitEXTests/SequencerEngineTests.swift

@@ -34,12 +34,14 @@ class SequencerEngineTests: XCTestCase {
 
         let orderedEvents = sequence.beatTimeOrderedEvents()
         orderedEvents.withUnsafeBufferPointer { (eventsPtr: UnsafeBufferPointer<SequenceEvent>) -> Void in
-            let observer = akSequencerEngineUpdateSequence(engine,
-                                                           eventsPtr.baseAddress,
-                                                           orderedEvents.count,
-                                                           settings,
-                                                           44100,
-                                                           block)!
+            akSequencerEngineUpdateSequence(engine,
+                                            eventsPtr.baseAddress,
+                                            orderedEvents.count,
+                                            settings,
+                                            44100,
+                                            block)
+
+            let observer = akSequencerGetRenderObserver(engine)!
 
             var timeStamp = AudioTimeStamp()
             timeStamp.mSampleTime = 0