From b07a6fd098c961e237291bb38ec739b765a1bd2f Mon Sep 17 00:00:00 2001
From: Christopher Snowhill <kode54@gmail.com>
Date: Tue, 3 Oct 2023 19:34:42 -0700
Subject: [PATCH] Visualization: Improve latency and buffering appearance

Adjust the buffering so if latency is too low, we fill the rest of
the output with silence instead of peeking at the oldest part
of the buffer. Also increase latency by half a buffer size so
that the requested sample is in the center of the buffer, which
improves the 4096 sample situation with the current low
latency output.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>
---
 Audio/Visualization/VisualizationController.swift | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/Audio/Visualization/VisualizationController.swift b/Audio/Visualization/VisualizationController.swift
index b77d764cb..6e22eb0e3 100644
--- a/Audio/Visualization/VisualizationController.swift
+++ b/Audio/Visualization/VisualizationController.swift
@@ -98,15 +98,26 @@ class VisualizationController : NSObject {
 		var outPCMCopy = Array<Float>(repeating: 0.0, count: 4096)
 
 		serialQueue.sync {
-			let latencySamples = (Int)(self.latency * self.sampleRate)
+			// 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 < 4096) {
+				// Latency can sometimes dip below this threshold
+				samplesToDo = latencySamples;
+			}
 			var j = self.visAudioCursor - latencySamples
 			let k = self.visAudioSize
 			if j < 0 { j += k }
-			for i in 0...4095 {
+			for i in 0..<samplesToDo {
 				let x = self.visAudio[j]
 				outPCMCopy[i] = x
 				j += 1; if j >= k { j = 0 }
 			}
+			if(samplesToDo < 4096) {
+				for i in samplesToDo...4095 {
+					outPCMCopy[i] = 0
+				}
+			}
 		}
 
 		if(outPCM != nil) {