Fix rounding errors (#22)

- Convert time -> sample time instead of sample time -> time
- This will be more precise as we are not working with fractions
- Use double instead of float in APIs (AudioTimeStamp->mSampleTime is double)

Author: jcavar

Sources/AudioKitEX/Automation/NodeParameter+Automation.swift

@@ -47,8 +47,8 @@ extension NodeParameter {
 
             guard let observer = ParameterAutomationGetRenderObserver(parameter.address,
                                                                       avAudioNode.auAudioUnit.scheduleParameterBlock,
-                                                                      Float(Settings.sampleRate),
-                                                                      Float(lastTime.sampleTime),
+                                                                      Double(Settings.sampleRate),
+                                                                      Double(lastTime.sampleTime),
                                                                       automationBaseAddress,
                                                                       events.count) else { return }
 

Sources/CAudioKitEX/Sequencing/ParameterAutomation.mm

@@ -12,8 +12,8 @@
 extern "C"
 AURenderObserver ParameterAutomationGetRenderObserver(AUParameterAddress address,
                                                       AUScheduleParameterBlock scheduleParameterBlock,
-                                                      float sampleRate,
-                                                      float startSampleTime,
+                                                      double sampleRate,
+                                                      double startSampleTime,
                                                       const struct AutomationEvent* eventsArray,
                                                       size_t count) {
 
@@ -33,16 +33,18 @@ AURenderObserver ParameterAutomationGetRenderObserver(AUParameterAddress address
     {
         if (actionFlags != kAudioUnitRenderAction_PreRender) return;
 
-        float blockStartTime = (timestamp->mSampleTime - startSampleTime) / sampleRate;
-        float blockEndTime = blockStartTime + frameCount / sampleRate;
+        double blockStartSample = timestamp->mSampleTime - startSampleTime;
+        double blockEndSample = blockStartSample + frameCount;
 
         AUValue initial = NAN;
 
         // Skip over events completely in the past to determine
         // an initial value.
         for (; index < count; ++index) {
             auto event = events[index];
-            if ( !(event.startTime + event.rampDuration < blockStartTime) ) {
+            double eventStartSample = event.startTime * sampleRate;
+            double rampSampleDuration = event.rampDuration * sampleRate;
+            if ( !(eventStartSample + rampSampleDuration < blockStartSample) ) {
                 break;
             }
             initial = event.targetValue;
@@ -59,11 +61,12 @@ AURenderObserver ParameterAutomationGetRenderObserver(AUParameterAddress address
         // Apply parameter automation for the segment.
         while (index < count) {
             auto event = events[index];
+            double eventStartSample = event.startTime * sampleRate;
 
             // Is it after the current block?
-            if (event.startTime >= blockEndTime) break;
+            if (eventStartSample >= blockEndSample) break;
 
-            AUEventSampleTime startTime = (event.startTime - blockStartTime) * sampleRate;
+            AUEventSampleTime startTime = eventStartSample - blockStartSample;
             AUAudioFrameCount duration = event.rampDuration * sampleRate;
 
             // If the event has already started, ensure we hit the targetValue

Sources/CAudioKitEX/include/ParameterAutomation.h

@@ -26,8 +26,8 @@ struct AutomationEvent {
 /// Returns a render observer block which will apply the automation to the selected parameter.
 AURenderObserver ParameterAutomationGetRenderObserver(AUParameterAddress address,
                                                       AUScheduleParameterBlock scheduleParameterBlock,
-                                                      float sampleRate,
-                                                      float startSampleTime,
+                                                      double sampleRate,
+                                                      double startSampleTime,
                                                       const struct AutomationEvent* events,
                                                       size_t count);
 

Tests/AudioKitEXTests/ParameterAutomationTests.swift

@@ -9,17 +9,17 @@ class ParameterAutomationTests: XCTestCase {
 
     func observerTest(events: [AutomationEvent],
                       sampleTime: Float64,
-                      startTime: Float = 0) -> ([AUParameterAddress], [AUValue], [AUAudioFrameCount]) {
+                      startTime: Double = 0) -> ([AUParameterAddress], [(AUValue, AUEventSampleTime)], [AUAudioFrameCount]) {
 
         let address = AUParameterAddress(42)
 
         var addresses: [AUParameterAddress] = []
-        var values: [AUValue] = []
+        var values: [(AUValue, AUEventSampleTime)] = []
         var durations: [AUAudioFrameCount] = []
 
         let scheduleParameterBlock: AUScheduleParameterBlock = { (sampleTime, rampDuration, address, value) in
             addresses.append(address)
-            values.append(value)
+            values.append((value, sampleTime))
             durations.append(rampDuration)
         }
 
@@ -42,13 +42,25 @@ class ParameterAutomationTests: XCTestCase {
 
     func testSimpleAutomation() throws {
 
-        let events = [ AutomationEvent(targetValue: 880, startTime: 0, rampDuration: 1.0) ]
+        let events = [AutomationEvent(targetValue: 880, startTime: 0, rampDuration: 0)]
 
         let (addresses, values, _) = observerTest(events: events, sampleTime: 0)
 
         // order is: taper, skew, offset, value
         XCTAssertEqual(addresses, [42])
-        XCTAssertEqual(values, [880.0])
+        XCTAssertEqual(values.map(\.0), [880.0])
+    }
+
+    func testSimpleAutomationWithBigValues() throws {
+
+        let events = [AutomationEvent(targetValue: 880, startTime: 0, rampDuration: 0)]
+
+        let (addresses, values, _) = observerTest(events: events, sampleTime: 1000000000, startTime: 1000000001)
+
+        // order is: taper, skew, offset, value
+        XCTAssertEqual(addresses, [42])
+        XCTAssertEqual(values.map(\.0), [880.0])
+        XCTAssertEqual(values.map(\.1), [1])
     }
 
     func testPastAutomation() {
@@ -59,7 +71,7 @@ class ParameterAutomationTests: XCTestCase {
 
         // If the automation is in the past, the value should be set to the final value.
         XCTAssertEqual(addresses, [42])
-        XCTAssertEqual(values, [880.0])
+        XCTAssertEqual(values.map(\.0), [880.0])
     }
 
     func testPastAutomationTwo() {
@@ -71,7 +83,7 @@ class ParameterAutomationTests: XCTestCase {
 
         // If the automation is in the past, the value should be set to the final value.
         XCTAssertEqual(addresses, [42])
-        XCTAssertEqual(values, [440.0])
+        XCTAssertEqual(values.map(\.0), [440.0])
 
     }
 
@@ -83,7 +95,7 @@ class ParameterAutomationTests: XCTestCase {
 
         // If the automation is in the future, we should not get anything.
         XCTAssertEqual(addresses, [])
-        XCTAssertEqual(values, [])
+        XCTAssertEqual(values.map(\.0), [])
     }
 
     func testAutomationMiddle() {
@@ -95,7 +107,7 @@ class ParameterAutomationTests: XCTestCase {
         let (addresses, values, durations) = observerTest(events: events, sampleTime: 128)
 
         XCTAssertEqual(addresses, [42])
-        XCTAssertEqual(values, [1.0])
+        XCTAssertEqual(values.map(\.0), [1.0])
         XCTAssertEqual(durations, [UInt32(44100-128)])
     }