Visualization: Make latency animation smoother

Compensate for latency by incrementing an offset
according to animation frame rate.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Audio/Visualization/VisualizationController.h

@@ -15,12 +15,15 @@ NS_ASSUME_NONNULL_BEGIN
 	float *visAudio;
 	int visAudioCursor, visAudioSize;
 	float *visAudioTemp;
+	uint64_t visSamplesPosted;
 }
 
 + (VisualizationController *)sharedController;
 
 - (void)postLatency:(double)latency;
 
+- (UInt64)samplesPosted;
+
 - (void)postSampleRate:(double)sampleRate;
 - (void)postVisPCM:(const float *)inPCM amount:(int)amount;
 - (double)readSampleRate;

Audio/Visualization/VisualizationController.swift

@@ -15,6 +15,7 @@ class VisualizationController : NSObject {
 	var visAudio: [Float] = Array(repeating: 0.0, count: 44100 * 45)
 	var visAudioCursor = 0
 	var visAudioSize = 0
+	var visSamplesPosted: UInt64 = 0
 
 	private static var sharedVisualizationController: VisualizationController = {
 		let visualizationController = VisualizationController()
@@ -34,6 +35,7 @@ class VisualizationController : NSObject {
 			for i in 0..<amount {
 				self.visAudio[i] = 0
 			}
+			self.visSamplesPosted = 0;
 		}
 	}
 
@@ -41,6 +43,11 @@ class VisualizationController : NSObject {
 	func postLatency(_ latency: Double) {
 		self.latency = latency
 	}
+	
+	@objc
+	func samplesPosted() -> UInt64 {
+		return self.visSamplesPosted
+	}
 
 	@objc
 	func postSampleRate(_ sampleRate: Double) {
@@ -67,6 +74,7 @@ class VisualizationController : NSObject {
 			}
 			self.visAudioCursor = j
 			self.latency += Double(amount) / self.sampleRate
+			self.visSamplesPosted += UInt64(amount);
 		}
 	}
 
@@ -101,6 +109,9 @@ class VisualizationController : NSObject {
 			// Offset latency so the target sample is in the center of the window
 			let latencySamples = (Int)((self.latency + latencyOffset) * self.sampleRate) + 2048
 			var samplesToDo = 4096;
+			if(latencySamples < 0) {
+				return;
+			}
 			if(latencySamples < 4096) {
 				// Latency can sometimes dip below this threshold
 				samplesToDo = latencySamples;

SpectrumViewCG.m

@@ -42,6 +42,9 @@ extern NSString *CogPlaybackDidStopNotificiation;
 	ddb_analyzer_draw_data_t _draw_data;
 
 	float visAudio[4096], visFFT[2048];
+
+	UInt64 visSamplesLastPosted;
+	double visLatencyOffset;
 }
 @end
 
@@ -234,6 +237,7 @@ extern NSString *CogPlaybackDidStopNotificiation;
 
 - (void)timerRun:(NSTimer *)timer {
 	[self repaint];
+	visLatencyOffset -= 1.0 / 60.0;
 }
 
 - (void)colorsDidChange:(NSNotification *)notification {
@@ -403,7 +407,13 @@ extern NSString *CogPlaybackDidStopNotificiation;
 		_analyzer.view_width = self.bounds.size.width;
 	}
 
-	[self->visController copyVisPCM:&visAudio[0] visFFT:&visFFT[0] latencyOffset:0];
+	UInt64 samplesPosted = [self->visController samplesPosted];
+	if (samplesPosted != visSamplesLastPosted) {
+		visSamplesLastPosted = samplesPosted;
+		visLatencyOffset = 0.0;
+	}
+
+	[self->visController copyVisPCM:&visAudio[0] visFFT:&visFFT[0] latencyOffset:visLatencyOffset];
 
 	ddb_analyzer_process(&_analyzer, [self->visController readSampleRate] / 2.0, 1, visFFT, 2048);
 	ddb_analyzer_tick(&_analyzer);

Visualization/SpectrumViewSK.m

@@ -45,6 +45,9 @@ extern NSString *CogPlaybackDidStopNotificiation;
 	SCNVector3 cameraEulerAngles3d;
 
 	float visAudio[4096], visFFT[2048];
+
+	UInt64 visSamplesLastPosted;
+	double visLatencyOffset;
 }
 @end
 
@@ -307,7 +310,13 @@ extern NSString *CogPlaybackDidStopNotificiation;
 		return;
 	}
 
-	[self->visController copyVisPCM:&visAudio[0] visFFT:&visFFT[0] latencyOffset:0];
+	UInt64 samplesPosted = [self->visController samplesPosted];
+	if (samplesPosted != visSamplesLastPosted) {
+		visSamplesLastPosted = samplesPosted;
+		visLatencyOffset = 0.0;
+	}
+
+	[self->visController copyVisPCM:&visAudio[0] visFFT:&visFFT[0] latencyOffset:visLatencyOffset];
 
 	ddb_analyzer_process(&_analyzer, [self->visController readSampleRate] / 2.0, 1, visFFT, 2048);
 	ddb_analyzer_tick(&_analyzer);
@@ -333,6 +342,7 @@ extern NSString *CogPlaybackDidStopNotificiation;
 
 - (void)timerRun:(NSTimer *)timer {
 	[self repaint];
+	visLatencyOffset -= 1.0 / 60.0;
 }
 
 - (void)startPlayback {