Second attempt to purge history

.gitattributes

@@ -0,0 +1,8 @@
+# used to remove files from deployment using `git archive`
+# git files
+.gitattributes export-ignore
+.gitignore export-ignore
+Documentation/Screenshots export-ignore
+Documentation/Demos export-ignore
+Resources/ffmpeg/ffmpeg export-ignore
+Resources/ffmpeg/ffprobe export-ignore

.gitignore

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+.DS_Store
+_Ignored
+Icons/
+TODO.txt
+iOS/Resources
+iOS/Frameworks
+macOS/Frameworks
+ToolsAndScripts/FFmpegBuild/xcframeworks
+Resources/ffmpeg/sharedLibs
+Resources/ffmpeg/ffmpeg-4.3.1
+*.zip
+Resources/ffmpeg/decoders.txt
+Resources/ffmpeg/decoders-stats.txt
+Resources/ffmpeg/parsers.txt
+Resources/releaseAutomation/*.dmg
+Resources/releaseAutomation/Aural Player*
+Resources/ffmpeg/audio-decoders.txt
+Documentation/Diagrams/Projects
+wiki/
+Resources/copyright.sh
+Resources/xml-copyright.sh
+UserGuide.pdf
+*.umdx
+unusedFiles.sh
+iOS/Resources/ffmpeg/build-iOS.sh
+macOS/Frameworks/libswresample.3.dylib
+macOS/Frameworks/libavutil.56.dylib
+macOS/Frameworks/libavformat.58.dylib
+macOS/Frameworks/libavcodec.58.dylib
+ToolsAndScripts/FFmpegBuild/xcframeworks/libavcodec.xcframework/Info.plist
+macOS/Aural-macOS.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved
+macOS/Aural-macOS.xcodeproj/project.xcworkspace/xcuserdata/kven.xcuserdatad/UserInterfaceState.xcuserstate

Core/AudioGraph/AudioEngine.swift

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+//
+//  AudioEngine.swift
+//  Aural
+//
+//  Copyright © 2024 Kartik Venugopal. All rights reserved.
+//
+//  This software is licensed under the MIT software license.
+//  See the file "LICENSE" in the project root directory for license terms.
+//
+import AVFoundation
+
+///
+/// Encapsulates an **AVAudioEngine** and provides convenient audio engine lifecycle functions.
+/// It also provides functions to add or remove audio processing nodes and manage their connections
+/// to each other.
+///
+class AudioEngine {
+
+    private let engine: AVAudioEngine
+
+    private var permanentNodes: [AVAudioNode] = []
+    private var removableNodes: [AVAudioNode] = []
+
+    private var allNodes: [AVAudioNode] {
+        permanentNodes + removableNodes
+    }
+
+    private(set) lazy var outputNode: AVAudioOutputNode = engine.outputNode
+    private(set) lazy var mainMixerNode: AVAudioMixerNode = engine.mainMixerNode
+
+    init() {
+        self.engine = AVAudioEngine()
+    }
+
+    // Connects all nodes in sequence.
+    func addNodes(permanentNodes: [AVAudioNode], removableNodes: [AVAudioNode]) {
+
+        self.permanentNodes = permanentNodes
+        self.removableNodes = removableNodes
+
+        let allNodes = self.allNodes
+
+        // Attach and connect the nodes, forming a chain.
+
+        allNodes.forEach {engine.attach($0)}
+
+        var input: AVAudioNode, output: AVAudioNode
+
+        // At least 2 nodes required for this to work
+        if allNodes.count >= 2 {
+
+            for i in 0...allNodes.count - 2 {
+
+                input = allNodes[i]
+                output = allNodes[i + 1]
+
+                engine.connect(input, to: output, format: nil)
+            }
+        }
+
+        // Connect last node to main mixer
+        engine.connect(allNodes.last!, to: mainMixerNode, format: nil)
+    }
+
+    func insertNode(_ node: AVAudioNode) {
+
+        guard let lastNode = allNodes.last else {return}
+
+        engine.disconnectNodeOutput(lastNode)
+
+        removableNodes.append(node)
+        engine.attach(node)
+
+        engine.connect(lastNode, to: node, format: nil)
+        engine.connect(node, to: mainMixerNode, format: nil)
+    }
+
+    // Assume indices are valid and sorted in descending order.
+    // NOTE - Indices are relative to the number of audio units, not actual node indices.
+    func removeNodes(at descendingIndices: [Int]) {
+
+        for index in descendingIndices {
+
+            var previousNode: AVAudioNode = permanentNodes.last!
+            var nextNode: AVAudioNode = engine.mainMixerNode
+
+            // Find the node previous to the node to be removed.
+            if index > 0 {
+
+                for previousIndex in stride(from: index - 1, to: -1, by: -1) {
+
+                    if !descendingIndices.contains(previousIndex) {
+
+                        previousNode = removableNodes[previousIndex]
+                        break
+                    }
+                }
+            }
+
+            // Find the node next to the node to be removed.
+            if index < removableNodes.lastIndex {
+
+                for nextIndex in (index + 1)...removableNodes.lastIndex {
+
+                    if !descendingIndices.contains(nextIndex) {
+
+                        nextNode = removableNodes[nextIndex]
+                        break
+                    }
+                }
+            }
+
+            // Sever the connections with the node to be removed.
+            engine.disconnectNodeOutput(previousNode)
+            engine.disconnectNodeInput(nextNode)
+
+            // Connect the previous / next node together.
+            engine.connect(previousNode, to: nextNode, format: nil)
+        }
+
+        for index in descendingIndices {
+            engine.detach(removableNodes.remove(at: index))
+        }
+    }
+
+    // Reconnects two nodes with the given audio format (required when a track change occurs)
+    func reconnect(outputOf node1: AVAudioNode, toInputOf node2: AVAudioNode, withFormat format: AVAudioFormat) {
+
+        engine.disconnectNodeOutput(node1)
+        engine.connect(node1, to: node2, format: format)
+    }
+
+    func start() {
+
+        do {
+            try engine.start()
+        } catch let error as NSError {
+            NSLog("Error starting audio engine: %@", error.description)
+        }
+    }
+
+    func stop() {
+        engine.stop()
+    }
+}