Bumping version

Fixes an issue where the memory is not released after paused audio (#33 )
Fixes unit tests
2021-12-06 20:01:12 +02:00 · 2021-12-06 19:58:50 +02:00 · 2021-10-05 18:55:34 +03:00 · 2021-10-05 18:32:55 +03:00 · 2021-09-07 15:47:59 +03:00 · 2021-09-07 15:36:51 +03:00
26 changed files with 546 additions and 153 deletions
@@ -153,7 +153,7 @@ extension PlayerControlsViewModel: AudioPlayerServiceDelegate {
        updateContent?(.updateMetadata(""))
    }

-    func errorOccured(error _: AudioPlayerError) {}
+    func errorOccurred(error _: AudioPlayerError) {}

    func metadataReceived(metadata: [String: String]) {
        guard !metadata.isEmpty else { return }
@@ -96,7 +96,7 @@ extension PlayerViewModel: AudioPlayerServiceDelegate {
        }
    }

-    func errorOccured(error _: AudioPlayerError) {
+    func errorOccurred(error _: AudioPlayerError) {
        currentPlayingItemIndex = nil
    }

@@ -13,7 +13,7 @@ protocol AudioPlayerServiceDelegate: AnyObject {
    func didStartPlaying()
    func didStopPlaying()
    func statusChanged(status: AudioPlayerState)
-    func errorOccured(error: AudioPlayerError)
+    func errorOccurred(error: AudioPlayerError)
    func metadataReceived(metadata: [String: String])
 }

@@ -168,7 +168,7 @@ extension AudioPlayerService: AudioPlayerDelegate {
    }

    func audioPlayerUnexpectedError(player _: AudioPlayer, error: AudioPlayerError) {
-        delegate.invoke(invocation: { $0.errorOccured(error: error) })
+        delegate.invoke(invocation: { $0.errorOccurred(error: error) })
    }

    func audioPlayerDidCancel(player _: AudioPlayer, queuedItems _: [AudioEntryId]) {}
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
  s.name = 'AudioStreaming'
-  s.version = '0.3.0'
+  s.version = '0.8.0'
  s.license = 'MIT'
  s.summary = 'An AudioPlayer/Streaming library for iOS written in Swift using AVAudioEngine.'
  s.homepage = 'https://github.com/dimitris-c/AudioStreaming'
@@ -52,7 +52,10 @@
 		B59DF1A32493E90C0043C498 /* AudioFileStream+Helpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = B59DF1A22493E90C0043C498 /* AudioFileStream+Helpers.swift */; };
 		B5AEDBB824744153007D8101 /* AudioStreaming.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = B5AEDBAE24744153007D8101 /* AudioStreaming.framework */; };
 		B5AEDBBF24744153007D8101 /* AudioStreaming.h in Headers */ = {isa = PBXBuildFile; fileRef = B5AEDBB124744153007D8101 /* AudioStreaming.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		B5B36E432655A32200DC96F5 /* FrameFilterProcessor.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5B36E422655A32200DC96F5 /* FrameFilterProcessor.swift */; };
 		B5B3B7CC248647ED00656828 /* AudioPlayerState.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5B3B7CB248647ED00656828 /* AudioPlayerState.swift */; };
+		B5D4A40925D9321400E1450C /* IcycastHeaderParser.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5D4A40825D9321400E1450C /* IcycastHeaderParser.swift */; };
+		B5D4A41025D948EF00E1450C /* IcycastHeadersProcessor.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5D4A40B25D9445600E1450C /* IcycastHeadersProcessor.swift */; };
 		B5D82E65255DD562009EDAA4 /* NetStatusService.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5D82E64255DD562009EDAA4 /* NetStatusService.swift */; };
 		B5DB66E2255C2EAB00B8DF53 /* AudioEntryProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5DB66E1255C2EAB00B8DF53 /* AudioEntryProvider.swift */; };
 		B5E1DE2524B70B4200955BFB /* AudioPlayerConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = B5E1DE2424B70B4200955BFB /* AudioPlayerConfiguration.swift */; };
@@ -142,7 +145,10 @@
 		B5AEDBB224744153007D8101 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		B5AEDBB724744153007D8101 /* AudioStreamingTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = AudioStreamingTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		B5AEDBBE24744153007D8101 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
+		B5B36E422655A32200DC96F5 /* FrameFilterProcessor.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FrameFilterProcessor.swift; sourceTree = "<group>"; };
 		B5B3B7CB248647ED00656828 /* AudioPlayerState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AudioPlayerState.swift; sourceTree = "<group>"; };
+		B5D4A40825D9321400E1450C /* IcycastHeaderParser.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = IcycastHeaderParser.swift; sourceTree = "<group>"; };
+		B5D4A40B25D9445600E1450C /* IcycastHeadersProcessor.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = IcycastHeadersProcessor.swift; sourceTree = "<group>"; };
 		B5D82E64255DD562009EDAA4 /* NetStatusService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NetStatusService.swift; sourceTree = "<group>"; };
 		B5DB66DA255C079C00B8DF53 /* AVFoundation.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = AVFoundation.framework; path = System/Library/Frameworks/AVFoundation.framework; sourceTree = SDKROOT; };
 		B5DB66E1255C2EAB00B8DF53 /* AudioEntryProvider.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AudioEntryProvider.swift; sourceTree = "<group>"; };
@@ -205,6 +211,7 @@
 				B55CEAB32485107C0001C498 /* Parser.swift */,
 				B55A736B247FCB420050C53D /* HTTPHeaderParser.swift */,
 				B55CE96D248058B60001C498 /* MetadataParser.swift */,
+				B5D4A40825D9321400E1450C /* IcycastHeaderParser.swift */,
 			);
 			path = Parsers;
 			sourceTree = "<group>";
@@ -254,9 +261,11 @@
 		B55CEAC024855AA20001C498 /* Processors */ = {
 			isa = PBXGroup;
 			children = (
+				B5B36E422655A32200DC96F5 /* FrameFilterProcessor.swift */,
 				B5667A8F2499018D00D93F85 /* AudioFileStreamProcessor.swift */,
 				B5667B3D249BC43000D93F85 /* AudioPlayerRenderProcessor.swift */,
 				B55CE97024810DE20001C498 /* MetadataStreamProcessor.swift */,
+				B5D4A40B25D9445600E1450C /* IcycastHeadersProcessor.swift */,
 			);
 			path = Processors;
 			sourceTree = "<group>";
@@ -594,6 +603,7 @@
 				B51B9F9A24DBE5BF00BDEAA2 /* AVAudioFormat+Convenience.swift in Sources */,
 				B51FE0C624890CCB00F2A4D2 /* PlayerQueueEntries.swift in Sources */,
 				B5EF9557247E9439003E8FF8 /* AudioStreamSource.swift in Sources */,
+				B5D4A40925D9321400E1450C /* IcycastHeaderParser.swift in Sources */,
 				B59DF1A32493E90C0043C498 /* AudioFileStream+Helpers.swift in Sources */,
 				B54D876D2490E4A000C361A0 /* UnitDescriptions.swift in Sources */,
 				B514657F248E3884005C03F7 /* DispatchTimerSource.swift in Sources */,
@@ -604,9 +614,11 @@
 				B5EF955B247EBCB3003E8FF8 /* AudioFileType.swift in Sources */,
 				B592E1252545FF9A008866FB /* BiMap.swift in Sources */,
 				B5DB66E2255C2EAB00B8DF53 /* AudioEntryProvider.swift in Sources */,
+				B5D4A41025D948EF00E1450C /* IcycastHeadersProcessor.swift in Sources */,
 				B5667A902499018D00D93F85 /* AudioFileStreamProcessor.swift in Sources */,
 				B59D0B6F255C904900D6CCE5 /* FileAudioSource.swift in Sources */,
 				B5EF9555247E9393003E8FF8 /* AudioEntry.swift in Sources */,
+				B5B36E432655A32200DC96F5 /* FrameFilterProcessor.swift in Sources */,
 				B51FE0C02488F67C00F2A4D2 /* Queue.swift in Sources */,
 				B5667A922499063D00D93F85 /* AudioPlayerContext.swift in Sources */,
 				B55CE97124810DE20001C498 /* MetadataStreamProcessor.swift in Sources */,
@@ -786,6 +798,7 @@
 			buildSettings = {
 				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_STYLE = Automatic;
+				CURRENT_PROJECT_VERSION = 2;
 				DEFINES_MODULE = YES;
 				DYLIB_COMPATIBILITY_VERSION = 1;
 				DYLIB_CURRENT_VERSION = 1;
@@ -798,7 +811,7 @@
 					"@executable_path/Frameworks",
 					"@loader_path/Frameworks",
 				);
-				MARKETING_VERSION = 0.3.0;
+				MARKETING_VERSION = 0.8.0;
 				OTHER_LDFLAGS = "-ObjC";
 				PRODUCT_BUNDLE_IDENTIFIER = com.decimal.AudioStreaming;
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
@@ -816,6 +829,7 @@
 			buildSettings = {
 				CLANG_ENABLE_MODULES = YES;
 				CODE_SIGN_STYLE = Automatic;
+				CURRENT_PROJECT_VERSION = 2;
 				DEFINES_MODULE = YES;
 				DYLIB_COMPATIBILITY_VERSION = 1;
 				DYLIB_CURRENT_VERSION = 1;
@@ -828,7 +842,7 @@
 					"@executable_path/Frameworks",
 					"@loader_path/Frameworks",
 				);
-				MARKETING_VERSION = 0.3.0;
+				MARKETING_VERSION = 0.8.0;
 				OTHER_LDFLAGS = "-ObjC";
 				PRODUCT_BUNDLE_IDENTIFIER = com.decimal.AudioStreaming;
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
@@ -9,7 +9,7 @@ extension AVAudioFormat {
    /// The underlying audio stream description.
    ///
    /// This exposes the `pointee` value of the `UsafePointer<AudioStreamBasicDescription>`
-    var basicStreamDescription: AudioStreamBasicDescription {
+    public var basicStreamDescription: AudioStreamBasicDescription {
        return streamDescription.pointee
    }
 }
@@ -31,7 +31,7 @@ internal enum Logger {
    }

    static func error(_ message: StaticString, category: Category, args: CVarArg...) {
-        proccess(message, category: category, type: .error, args: args)
+        process(message, category: category, type: .error, args: args)
    }

    static func error(_ message: StaticString, category: Category) {
@@ -39,14 +39,14 @@ internal enum Logger {
    }

    static func debug(_ message: StaticString, category: Category, args: CVarArg...) {
-        proccess(message, category: category, type: .debug, args: args)
+        process(message, category: category, type: .debug, args: args)
    }

    static func debug(_ message: StaticString, category: Category) {
        debug(message, category: category, args: [])
    }

-    private static func proccess(_ message: StaticString, category: Category, type: OSLogType, args: CVarArg...) {
+    private static func process(_ message: StaticString, category: Category, type: OSLogType, args: CVarArg...) {
        guard isEnabled else { return }
        os_log(message, log: category.toOSLog(), type: type, args)
    }
@@ -53,7 +53,7 @@ internal class AudioEntry {
        return Double(audioStreamFormat.mFramesPerPacket) / Double(sampleRate)
    }

-    private var avaragePacketByteSize: Double {
+    private var averagePacketByteSize: Double {
        let packets = processedPacketsState
        guard !packets.isEmpty else { return 0 }
        return Double(packets.sizeTotal / packets.count)
@@ -109,7 +109,7 @@ internal class AudioEntry {
            if packetsCount > estimationMinPacketsPreferred ||
                (audioStreamFormat.mBytesPerFrame == 0 && packetsCount > estimationMinPackets)
            {
-                return avaragePacketByteSize / packetDuration * 8
+                return averagePacketByteSize / packetDuration * 8
            }
        }
        return (Double(audioStreamFormat.mBytesPerFrame) * audioStreamFormat.mSampleRate) * 8
@@ -151,12 +151,12 @@ extension AudioEntry: AudioStreamSourceDelegate {
        delegate?.dataAvailable(source: source, data: data)
    }

-    func errorOccured(source: CoreAudioStreamSource, error: Error) {
-        delegate?.errorOccured(source: source, error: error)
+    func errorOccurred(source: CoreAudioStreamSource, error: Error) {
+        delegate?.errorOccurred(source: source, error: error)
    }

-    func endOfFileOccured(source: CoreAudioStreamSource) {
-        delegate?.endOfFileOccured(source: source)
+    func endOfFileOccurred(source: CoreAudioStreamSource) {
+        delegate?.endOfFileOccurred(source: source)
    }

    func metadataReceived(data: [String: String]) {
@@ -46,10 +46,10 @@ final class AudioEntryProvider: AudioEntryProviding {
        FileAudioSource(url: url, underlyingQueue: underlyingQueue)
    }

-    func source(for url: URL, headers _: [String: String]) -> CoreAudioStreamSource {
+    func source(for url: URL, headers: [String: String]) -> CoreAudioStreamSource {
        guard !url.isFileURL else {
            return provideFileAudioSource(url: url)
        }
-        return provideAudioSource(url: url, headers: [:])
+        return provideAudioSource(url: url, headers: headers)
    }
 }
@@ -10,9 +10,9 @@ protocol AudioStreamSourceDelegate: AnyObject {
    /// Indicates that there's data available
    func dataAvailable(source: CoreAudioStreamSource, data: Data)
    /// Indicates an error occurred
-    func errorOccured(source: CoreAudioStreamSource, error: Error)
+    func errorOccurred(source: CoreAudioStreamSource, error: Error)
    /// Indicates end of file has occurred
-    func endOfFileOccured(source: CoreAudioStreamSource)
+    func endOfFileOccurred(source: CoreAudioStreamSource)
    /// Indicates metadata read from stream
    func metadataReceived(data: [String: String])
 }
@@ -74,7 +74,7 @@ final class FileAudioSource: NSObject, CoreAudioStreamSource {
        do {
            try performOpen(seek: offset)
        } catch {
-            delegate?.errorOccured(source: self, error: error)
+            delegate?.errorOccurred(source: self, error: error)
        }
    }

@@ -139,11 +139,11 @@ extension FileAudioSource: StreamDelegate {
        case .hasBytesAvailable:
            dataAvailable()
        case .endEncountered:
-            delegate?.endOfFileOccured(source: self)
+            delegate?.endOfFileOccurred(source: self)
        case .errorOccurred:
-            delegate?.errorOccured(source: self, error: AudioPlayerError.codecError)
+            delegate?.errorOccurred(source: self, error: AudioPlayerError.codecError)
        case .endEncountered:
-            delegate?.endOfFileOccured(source: self)
+            delegate?.endOfFileOccurred(source: self)
        default:
            break
        }
@@ -33,6 +33,9 @@ public class RemoteAudioSource: AudioStreamSource {

    internal var metadataStreamProcessor: MetadataStreamSource

+    private var shouldTryParsingIcycastHeaders: Bool = false
+    private let icycastHeadersProcessor: IcycastHeadersProcessor
+
    internal var audioFileHint: AudioFileTypeID {
        guard let output = parsedHeaderOutput, output.typeId != 0 else {
            return audioFileType(fileExtension: url.pathExtension)
@@ -48,6 +51,7 @@ public class RemoteAudioSource: AudioStreamSource {

    init(networking: NetworkingClient,
         metadataStreamSource: MetadataStreamSource,
+         icycastHeadersProcessor: IcycastHeadersProcessor,
         netStatusProvider: NetStatusProvider,
         retrier: Retrier,
         url: URL,
@@ -62,6 +66,7 @@ public class RemoteAudioSource: AudioStreamSource {
        seekOffset = 0
        supportsSeek = false
        netStatusService = netStatusProvider
+        self.icycastHeadersProcessor = icycastHeadersProcessor
        self.underlyingQueue = underlyingQueue
        streamOperationQueue = OperationQueue()
        streamOperationQueue.underlyingQueue = underlyingQueue
@@ -80,11 +85,13 @@ public class RemoteAudioSource: AudioStreamSource {
        let metadataParser = MetadataParser()
        let metadataProcessor = MetadataStreamProcessor(parser: metadataParser.eraseToAnyParser())
        let netStatusProvider = NetStatusService(network: NWPathMonitor())
-        let retrierTimout = Retrier(interval: .seconds(1), maxInterval: 5, underlyingQueue: nil)
+        let icyheaderProcessor = IcycastHeadersProcessor()
+        let retrierTimeout = Retrier(interval: .seconds(1), maxInterval: 5, underlyingQueue: nil)
        self.init(networking: networking,
                  metadataStreamSource: metadataProcessor,
+                  icycastHeadersProcessor: icyheaderProcessor,
                  netStatusProvider: netStatusProvider,
-                  retrier: retrierTimout,
+                  retrier: retrierTimeout,
                  url: url,
                  underlyingQueue: underlyingQueue,
                  httpHeaders: httpHeaders)
@@ -103,7 +110,7 @@ public class RemoteAudioSource: AudioStreamSource {
    func close() {
        retrierTimeout.cancel()
        netStatusService.stop()
-        streamOperationQueue.isSuspended = true
+        streamOperationQueue.isSuspended = false
        streamOperationQueue.cancelAllOperations()
        if let streamTask = streamRequest {
            streamTask.cancel()
@@ -124,17 +131,17 @@ public class RemoteAudioSource: AudioStreamSource {

        retrierTimeout.cancel()
        metadataStreamProcessor.reset()
+        icycastHeadersProcessor.reset()
+        shouldTryParsingIcycastHeaders = false

        performOpen(seek: offset)
    }

    func suspend() {
-        streamRequest?.suspend()
        streamOperationQueue.isSuspended = true
    }

    func resume() {
-        streamRequest?.resume()
        streamOperationQueue.isSuspended = false
    }

@@ -176,11 +183,11 @@ public class RemoteAudioSource: AudioStreamSource {
            handleStreamEvent(event: event)
        case let .complete(event):
            if let error = event.error {
-                delegate?.errorOccured(source: self, error: error)
+                delegate?.errorOccurred(source: self, error: error)
            } else {
                addCompletionOperation { [weak self] in
                    guard let self = self else { return }
-                    self.delegate?.endOfFileOccured(source: self)
+                    self.delegate?.endOfFileOccurred(source: self)
                }
            }
        }
@@ -189,16 +196,25 @@ public class RemoteAudioSource: AudioStreamSource {
    private func handleStreamEvent(event: NetworkDataStream.StreamResult) {
        switch event {
        case let .success(value):
-            if let data = value.data {
+            if let audioData = value.data {
                addStreamOperation { [weak self] in
                    guard let self = self else { return }
-                    if self.metadataStreamProcessor.canProccessMetadata {
-                        let extractedAudioData = self.metadataStreamProcessor.proccessMetadata(data: data)
-                        self.delegate?.dataAvailable(source: self, data: extractedAudioData)
-                    } else {
-                        self.delegate?.dataAvailable(source: self, data: data)
+                    if self.shouldTryParsingIcycastHeaders {
+                        let (header, extractedAudio) = self.icycastHeadersProcessor.process(data: audioData)
+                        if let header = header {
+                            self.shouldTryParsingIcycastHeaders = false
+                            let parser = IcycastHeaderParser()
+                            self.parsedHeaderOutput = parser.parse(input: header)
+                            if let metadataStep = self.parsedHeaderOutput?.metadataStep {
+                                self.metadataStreamProcessor.metadataAvailable(step: metadataStep)
+                            }
+                        }
+                        let audioCount = self.processAudio(data: extractedAudio)
+                        self.relativePosition += audioCount
+                        return
                    }
-                    self.relativePosition += data.count
+                    let audioCount = self.processAudio(data: audioData)
+                    self.relativePosition += audioCount
                }
            }
        case .failure:
@@ -211,12 +227,32 @@ public class RemoteAudioSource: AudioStreamSource {
        }
    }

+    /// Processing audio data, extracting metadata if needed.
+    /// - Parameter data: The audio to be processed
+    /// - Returns: An `Int` value representing the amount of audio data bytes.
+    private func processAudio(data: Data) -> Int {
+        if self.metadataStreamProcessor.canProcessMetadata {
+            let extractedAudioData = self.metadataStreamProcessor.processMetadata(data: data)
+            self.delegate?.dataAvailable(source: self, data: extractedAudioData)
+            return extractedAudioData.count
+        } else {
+            self.delegate?.dataAvailable(source: self, data: data)
+            return data.count
+        }
+    }
+
    private func parseResponseHeader(response: HTTPURLResponse?) {
        guard let response = response else { return }
        let httpStatusCode = response.statusCode
        let parser = HTTPHeaderParser()
        parsedHeaderOutput = parser.parse(input: response)

+        if parsedHeaderOutput == nil {
+            shouldTryParsingIcycastHeaders = true
+            checkHTTP(statusCode: httpStatusCode)
+            return
+        }
+
        if let acceptRanges = parser.value(forHTTPHeaderField: HeaderField.acceptRanges, in: response) {
            supportsSeek = acceptRanges != "none"
        }
@@ -225,12 +261,16 @@ public class RemoteAudioSource: AudioStreamSource {
        if let metadataStep = parsedHeaderOutput?.metadataStep {
            metadataStreamProcessor.metadataAvailable(step: metadataStep)
        }
+        checkHTTP(statusCode: httpStatusCode)
+    }
+
+    private func checkHTTP(statusCode: Int) {
        // check for error
-        if httpStatusCode == 416 { // range not satisfied error
+        if statusCode == 416 { // range not satisfied error
            if length >= 0 { seekOffset = length }
-            delegate?.endOfFileOccured(source: self)
-        } else if httpStatusCode >= 300 {
-            delegate?.errorOccured(source: self, error: NetworkError.serverError)
+            delegate?.endOfFileOccurred(source: self)
+        } else if statusCode >= 300 {
+            delegate?.errorOccurred(source: self, error: NetworkError.serverError)
        }
    }

@@ -6,7 +6,7 @@
 import AVFoundation
 import CoreAudio

-public final class AudioPlayer {
+open class AudioPlayer {
    public weak var delegate: AudioPlayerDelegate?

    public var muted: Bool {
@@ -86,6 +86,19 @@ public final class AudioPlayer {
    /// The current configuration of the player.
    public let configuration: AudioPlayerConfiguration

+    /// A Boolean value that indicates whether the audio engine is running.
+    /// `true` if the engine is running, otherwise, `false`
+    public var isEngineRunning: Bool { audioEngine.isRunning }
+
+    /// The `AVAudioMixerNode` as created by the underlying audio engine
+    public var mainMixerNode: AVAudioMixerNode {
+        audioEngine.mainMixerNode
+    }
+
+    public var frameFiltering: FrameFiltering {
+        frameFilterProcessor
+    }
+
    /// An `AVAudioFormat` object for the canonical audio stream
    private var outputAudioFormat: AVAudioFormat = {
        AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: 44100.0, channels: 2, interleaved: true)!
@@ -95,27 +108,23 @@ public final class AudioPlayer {
    private var stateBeforePaused: InternalState = .initial

    /// The underlying `AVAudioEngine` object
-    let audioEngine = AVAudioEngine()
+    private let audioEngine = AVAudioEngine()
    /// An `AVAudioUnit` object that represents the audio player
    private(set) var player = AVAudioUnit()
    /// An `AVAudioUnitTimePitch` that controls the playback rate of the audio engine
-    let rateNode = AVAudioUnitTimePitch()
-
-    /// A Boolean value that indicates whether the audio engine is running.
-    /// `true` if the engine is running, otherwise, `false`
-    var isEngineRunning: Bool { audioEngine.isRunning }
+    private let rateNode = AVAudioUnitTimePitch()

    /// An object representing the context of the audio render.
    /// Holds the audio buffer and in/out lists as required by the audio rendering
-    let rendererContext: AudioRendererContext
+    private let rendererContext: AudioRendererContext
    /// An object representing the context of the player.
    /// Holds the player's state, current playing and reading entries.
-    let playerContext: AudioPlayerContext
+    private let playerContext: AudioPlayerContext

-    let fileStreamProcessor: AudioFileStreamProcessor
-    let playerRenderProcessor: AudioPlayerRenderProcessor
+    private let fileStreamProcessor: AudioFileStreamProcessor
+    private let playerRenderProcessor: AudioPlayerRenderProcessor
+    private let frameFilterProcessor: FrameFilterProcessor

-    private let audioReadSource: DispatchTimerSource
    private let serializationQueue: DispatchQueue
    private let sourceQueue: DispatchQueue

@@ -132,7 +141,6 @@ public final class AudioPlayer {

        serializationQueue = DispatchQueue(label: "streaming.core.queue", qos: .userInitiated)
        sourceQueue = DispatchQueue(label: "source.queue", qos: .userInitiated)
-        audioReadSource = DispatchTimerSource(interval: .milliseconds(200), queue: sourceQueue)

        entryProvider = AudioEntryProvider(networkingClient: NetworkingClient(),
                                           underlyingQueue: sourceQueue,
@@ -142,6 +150,8 @@ public final class AudioPlayer {
                                                       rendererContext: rendererContext,
                                                       outputAudioFormat: outputAudioFormat.basicStreamDescription)

+        frameFilterProcessor = FrameFilterProcessor(mixerNode: audioEngine.mainMixerNode)
+
        playerRenderProcessor = AudioPlayerRenderProcessor(playerContext: playerContext,
                                                           rendererContext: rendererContext,
                                                           outputAudioFormat: outputAudioFormat.basicStreamDescription)
@@ -154,7 +164,6 @@ public final class AudioPlayer {
    deinit {
        playerContext.audioPlayingEntry?.close()
        clearQueue()
-        stopReadProccessFromSource()
        rendererContext.clean()
    }

@@ -183,14 +192,13 @@ public final class AudioPlayer {
            do {
                try self.startEngineIfNeeded()
            } catch {
-                self.raiseUnxpected(error: .audioSystemError(.engineFailure))
+                self.raiseUnexpected(error: .audioSystemError(.engineFailure))
            }
        }

        sourceQueue.async { [weak self] in
            guard let self = self else { return }
            self.processSource()
-            self.startReadProcessFromSourceIfNeeded()
        }
    }

@@ -246,7 +254,6 @@ public final class AudioPlayer {
    public func stop() {
        guard playerContext.internalState != .stopped else { return }

-        stopReadProccessFromSource()
        serializationQueue.sync {
            stopEngine(reason: .userAction)
        }
@@ -277,7 +284,6 @@ public final class AudioPlayer {
            serializationQueue.sync {
                pauseEngine()
            }
-            stopReadProccessFromSource()
            playerContext.audioPlayingEntry?.suspend()
            sourceQueue.async { [weak self] in
                self?.processSource()
@@ -303,9 +309,10 @@ public final class AudioPlayer {
            }
            startPlayer(resetBuffers: false)
        }
-        startReadProcessFromSourceIfNeeded()
    }

+    /// Seeks the audio to the specified time.
+    /// - Parameter time: A `Double` value specifing the time of the requested seek in seconds
    public func seek(to time: Double) {
        guard let playingEntry = playerContext.audioPlayingEntry else {
            return
@@ -328,10 +335,16 @@ public final class AudioPlayer {
        }
    }

+    /// Attaches the given `AVAudioNode` to the engine
+    /// - Note: The node will be added after the default rate node
+    /// - Parameter node: An instance of `AVAudioNode`
    public func attach(node: AVAudioNode) {
        attach(nodes: [node])
    }

+    /// Attaches the given `AVAudioNode`s to the engine
+    /// - Note: The nodes will be added after the default rate node
+    /// - Parameter node: An array of `AVAudioNode` instances
    public func attach(nodes: [AVAudioNode]) {
        nodes.forEach { node in
            customAttachedNodes.append(node)
@@ -341,6 +354,8 @@ public final class AudioPlayer {
        reattachCustomNodes()
    }

+    /// Detaches the given `AVAudioNode` from the engine
+    /// - Parameter node: An instance of `AVAudioNode`
    public func detach(node: AVAudioNode) {
        guard customAttachedNodes.contains(node) else {
            return
@@ -350,6 +365,8 @@ public final class AudioPlayer {
        reattachCustomNodes()
    }

+    /// Detaches the given `AVAudioNode`s from the engine
+    /// - Parameter node: An array of `AVAudioNode` instances
    public func detachCustomAttachedNodes() {
        customAttachedNodes.forEach { node in
            audioEngine.detach(node)
@@ -400,7 +417,7 @@ public final class AudioPlayer {
                self.playerRenderProcessor.attachCallback(on: unit, audioFormat: self.outputAudioFormat)
            case let .failure(error):
                assertionFailure("couldn't create player unit: \(error)")
-                self.raiseUnxpected(error: .audioSystemError(.playerNotFound))
+                self.raiseUnexpected(error: .audioSystemError(.playerNotFound))
            }
        }
    }
@@ -428,12 +445,12 @@ public final class AudioPlayer {
        fileStreamProcessor.fileStreamCallback = { [weak self] effect in
            guard let self = self else { return }
            switch effect {
-            case .proccessSource:
+            case .processSource:
                self.sourceQueue.async {
                    self.processSource()
                }
            case let .raiseError(error):
-                self.raiseUnxpected(error: error)
+                self.raiseUnexpected(error: error)
            }
        }
    }
@@ -506,23 +523,6 @@ public final class AudioPlayer {
        Logger.debug("engine stopped 🛑", category: .generic)
    }

-    /// Starts the timer of `audioReadSource` for proccesing the source read stream
-    ///
-    /// This calls `processSource` method every `500 ms`
-    private func startReadProcessFromSourceIfNeeded() {
-        guard audioReadSource.state != .activated else { return }
-        audioReadSource.add { [weak self] in
-            self?.processSource()
-        }
-        audioReadSource.activate()
-    }
-
-    /// Stops and removes the handler from the timer, @see `audioReadSource`
-    private func stopReadProccessFromSource() {
-        audioReadSource.suspend()
-        audioReadSource.removeHandler()
-    }
-
    /// Starts the audio player, reseting the buffers if requested
    ///
    /// - parameter resetBuffers: A `Bool` value indicating if the buffers should be reset, prior starting the player.
@@ -536,7 +536,7 @@ public final class AudioPlayer {
            try player.auAudioUnit.startHardware()
        } catch {
            stopEngine(reason: .error)
-            raiseUnxpected(error: .audioSystemError(.playerStartError))
+            raiseUnexpected(error: .audioSystemError(.playerStartError))
        }
    }

@@ -544,7 +544,6 @@ public final class AudioPlayer {
    private func processSource() {
        dispatchPrecondition(condition: .onQueue(sourceQueue))

-        guard !playerContext.disposedRequested else { return }
        guard playerContext.internalState != .paused else { return }

        if playerContext.internalState == .pendingNext {
@@ -581,7 +580,6 @@ public final class AudioPlayer {
                setCurrentReading(entry: entry, startPlaying: shouldStartPlaying, shouldClearQueue: false)
            } else if playerContext.audioPlayingEntry == nil {
                if playerContext.internalState != .stopped {
-                    stopReadProccessFromSource()
                    stopEngine(reason: .eof)
                }
            }
@@ -597,7 +595,7 @@ public final class AudioPlayer {
            playingEntry.seekRequest.lock.unlock()

            if originalSeekToTimeRequested, playerContext.audioReadingEntry === playingEntry {
-                proccessSeekTime()
+                processSeekTime()

                let version = playingEntry.seekRequest.version.value
                if currSeekVersion == version {
@@ -609,7 +607,7 @@ public final class AudioPlayer {
        }
    }

-    private func proccessSeekTime() {
+    private func processSeekTime() {
        assert(playerContext.audioReadingEntry === playerContext.audioPlayingEntry,
               "reading and playing entry must be the same")
        fileStreamProcessor.processSeek()
@@ -724,7 +722,7 @@ public final class AudioPlayer {
        }
    }

-    private func raiseUnxpected(error: AudioPlayerError) {
+    private func raiseUnexpected(error: AudioPlayerError) {
        playerContext.setInternalState(to: .error)
        // todo raise on main thread from playback thread
        asyncOnMain { [weak self] in
@@ -745,7 +743,7 @@ extension AudioPlayer: AudioStreamSourceDelegate {
            let openFileStreamStatus = fileStreamProcessor.openFileStream(with: source.audioFileHint)
            guard openFileStreamStatus == noErr else {
                let streamError = AudioFileStreamError(status: openFileStreamStatus)
-                raiseUnxpected(error: .audioSystemError(.fileStreamError(streamError)))
+                raiseUnexpected(error: .audioSystemError(.fileStreamError(streamError)))
                return
            }
        }
@@ -755,7 +753,7 @@ extension AudioPlayer: AudioStreamSourceDelegate {
            guard streamBytesStatus == noErr else {
                if let playingEntry = playerContext.audioPlayingEntry, playingEntry.has(same: source) {
                    let streamBytesError = AudioFileStreamError(status: streamBytesStatus)
-                    raiseUnxpected(error: .streamParseBytesFailure(streamBytesError))
+                    raiseUnexpected(error: .streamParseBytesFailure(streamBytesError))
                }
                return
            }
@@ -766,12 +764,12 @@ extension AudioPlayer: AudioStreamSourceDelegate {
        }
    }

-    func errorOccured(source: CoreAudioStreamSource, error: Error) {
+    func errorOccurred(source: CoreAudioStreamSource, error: Error) {
        guard let entry = playerContext.audioReadingEntry, entry.has(same: source) else { return }
-        raiseUnxpected(error: .networkError(.failure(error)))
+        raiseUnexpected(error: .networkError(.failure(error)))
    }

-    func endOfFileOccured(source: CoreAudioStreamSource) {
+    func endOfFileOccurred(source: CoreAudioStreamSource) {
        let hasSameSource = playerContext.audioReadingEntry?.has(same: source) ?? false
        guard playerContext.audioReadingEntry == nil || hasSameSource else {
            source.delegate = nil
@@ -802,7 +800,10 @@ extension AudioPlayer: AudioStreamSourceDelegate {
        playerContext.audioReadingEntry = nil
        playerContext.entriesLock.unlock()

-        processSource()
+        sourceQueue.async { [weak self] in
+            guard let self = self else { return }
+            self.processSource()
+        }
    }

    func metadataReceived(data: [String: String]) {
@@ -6,30 +6,31 @@
 import Foundation

 internal final class AudioPlayerContext {
-    var stopReason = Protected<AudioPlayerStopReason>(.none)
+    var stopReason: Protected<AudioPlayerStopReason>

-    var state = Protected<AudioPlayerState>(.ready)
+    var state: Protected<AudioPlayerState>
    var stateChanged: ((_ oldState: AudioPlayerState, _ newState: AudioPlayerState) -> Void)?

-    var muted = Protected<Bool>(false)
+    var muted: Protected<Bool>

    var internalState: AudioPlayer.InternalState {
        playerInternalState.value
    }

-    let entriesLock = UnfairLock()
+    let entriesLock: UnfairLock
    var audioReadingEntry: AudioEntry?
    var audioPlayingEntry: AudioEntry?

-    var disposedRequested: Bool
-
    /// This is the player's internal state to use
    /// - NOTE: Do not use directly instead use the `internalState` to set and get the property
    /// or the `setInternalState(to:when:)`method
    private var playerInternalState = Protected<AudioPlayer.InternalState>(.initial)

    init() {
-        disposedRequested = false
+        stopReason = Protected<AudioPlayerStopReason>(.none)
+        state = Protected<AudioPlayerState>(.ready)
+        muted = Protected<Bool>(false)
+        entriesLock = UnfairLock()
    }

    /// Sets the internal state if given the `inState` will be evaluated before assignment occurs.
@@ -22,7 +22,7 @@ public protocol AudioPlayerDelegate: AnyObject {
                                     stopReason: AudioPlayerStopReason,
                                     progress: Double,
                                     duration: Double)
-    /// Tells the delegate when an unexpected error occured.
+    /// Tells the delegate when an unexpected error occurred.
    /// - note: Probably a good time to recreate the player when this occurs
    func audioPlayerUnexpectedError(player: AudioPlayer, error: AudioPlayerError)

@@ -20,8 +20,6 @@ final class AudioRendererContext {

    let packetsSemaphore = DispatchSemaphore(value: 0)

-    var discontinuous: Bool = false
-
    let framesRequiredToStartPlaying: UInt32
    let framesRequiredAfterRebuffering: UInt32
    let framesRequiredForDataAfterSeekPlaying: UInt32
@@ -9,7 +9,7 @@ import AVFoundation

 enum AudioConvertStatus: Int32 {
    case done = 100
-    case proccessed = 0
+    case processed = 0
 }

 struct AudioConvertInfo {
@@ -20,11 +20,11 @@ struct AudioConvertInfo {
 }

 enum FileStreamProcessorEffect {
-    case proccessSource
+    case processSource
    case raiseError(AudioPlayerError)
 }

-/// An object that handles the proccessing of AudioFileStream, its packets etc.
+/// An object that handles the processing of AudioFileStream, its packets etc.
 final class AudioFileStreamProcessor {
    private let maxCompressedPacketForBitrate = 4096

@@ -38,8 +38,9 @@ final class AudioFileStreamProcessor {
    internal var audioConverter: AudioConverterRef?
    internal var discontinuous: Bool = false
    internal var inputFormat = AudioStreamBasicDescription()
-    internal var fileFormat: String = ""
-    internal let fa4mFormat = "fa4m"
+
+    internal var currentFileFormat: String = ""
+    internal let fileFormatsForDelayedConverterCreation: Set = ["fa4m", "f4pm"]

    var isFileStreamOpen: Bool {
        audioFileStream != nil
@@ -165,7 +166,7 @@ final class AudioFileStreamProcessor {

        var classDesc = AudioClassDescription()
        var outputFormat = toFormat
-        if getHardwareCodecClassDescripition(formatId: inputFormat.mFormatID, classDesc: &classDesc) {
+        if getHardwareCodecClassDescription(formatId: inputFormat.mFormatID, classDesc: &classDesc) {
            AudioConverterNewSpecific(&inputFormat, &outputFormat, 1, &classDesc, &audioConverter)
        }

@@ -178,11 +179,12 @@ final class AudioFileStreamProcessor {
            }
        }
        self.inputFormat = inputFormat
+        assignMagicCookieToConverterIfNeeded()
+    }

+    private func assignMagicCookieToConverterIfNeeded() {
        // magic cookie info
-        let fileHint = playerContext.audioReadingEntry?.audioFileHint
-        let isProperFormat = fileHint != kAudioFileAAC_ADTSType && fileHint != kAudioFileM4AType && fileHint != kAudioFileMPEG4Type
-        if let fileStream = audioFileStream, isProperFormat {
+        if let fileStream = audioFileStream {
            var cookieSize: UInt32 = 0
            guard AudioFileStreamGetPropertyInfo(fileStream, kAudioFileStreamProperty_MagicCookieData, &cookieSize, nil) == noErr else {
                return
@@ -263,7 +265,7 @@ final class AudioFileStreamProcessor {
        var size = UInt32(4)
        AudioFileStreamGetProperty(fileStream, kAudioFileStreamProperty_FileFormat, &size, &fileFormat)
        if let stringFileFormat = String(data: Data(fileFormat), encoding: .utf8) {
-            self.fileFormat = stringFileFormat
+            self.currentFileFormat = stringFileFormat
        }
    }

@@ -293,7 +295,7 @@ final class AudioFileStreamProcessor {
                entry.processedPacketsState.bufferSize = packetBufferSize
            }

-            if fileFormat != fa4mFormat {
+            if !fileFormatsForDelayedConverterCreation.contains(currentFileFormat) {
                createAudioConverter(from: entry.audioStreamFormat, to: outputAudioFormat)
            }
        }
@@ -331,7 +333,7 @@ final class AudioFileStreamProcessor {
            i += step
        }

-        if fileFormat == fa4mFormat {
+        if fileFormatsForDelayedConverterCreation.contains(currentFileFormat) {
            if let inputStreamFormat = playerContext.audioReadingEntry?.audioStreamFormat {
                createAudioConverter(from: inputStreamFormat, to: outputAudioFormat)
            }
@@ -346,12 +348,12 @@ final class AudioFileStreamProcessor {
                             inPacketDescriptions: UnsafeMutablePointer<AudioStreamPacketDescription>?)
    {
        guard let entry = playerContext.audioReadingEntry else { return }
-        guard entry.audioStreamState.processedDataFormat, !playerContext.disposedRequested else { return }
+        guard entry.audioStreamState.processedDataFormat else { return }

        if let playingEntry = playerContext.audioPlayingEntry,
           playingEntry.seekRequest.requested, playingEntry.calculatedBitrate() > 0
        {
-            fileStreamCallback?(.proccessSource)
+            fileStreamCallback?(.processSource)
            if rendererContext.waiting.value {
                rendererContext.packetsSemaphore.signal()
            }
@@ -375,11 +377,11 @@ final class AudioFileStreamProcessor {
            convertInfo.audioBuffer.mNumberChannels = playingAudioStreamFormat.mChannelsPerFrame
        }

-        updateProccessedPackets(inPacketDescriptions: inPacketDescriptions,
+        updateProcessedPackets(inPacketDescriptions: inPacketDescriptions,
                                inNumberPackets: inNumberPackets)

        var status: OSStatus = noErr
-        packetProccess: while status == noErr {
+        packetProcess: while status == noErr {
            rendererContext.lock.lock()
            let bufferContext = rendererContext.bufferContext
            var used = bufferContext.frameUsedCount
@@ -401,8 +403,7 @@ final class AudioFileStreamProcessor {
                    if framesLeftInBuffer > 0 {
                        break
                    }
-                    if playerContext.disposedRequested
-                        || playerContext.internalState == .disposed
+                    if playerContext.internalState == .disposed
                        || playerContext.internalState == .pendingNext
                        || playerContext.internalState == .stopped
                    {
@@ -412,7 +413,7 @@ final class AudioFileStreamProcessor {
                    if let playingEntry = playerContext.audioPlayingEntry,
                       playingEntry.seekRequest.requested, playingEntry.calculatedBitrate() > 0
                    {
-                        fileStreamCallback?(.proccessSource)
+                        fileStreamCallback?(.processSource)
                        if rendererContext.waiting.value {
                            rendererContext.packetsSemaphore.signal()
                        }
@@ -457,7 +458,7 @@ final class AudioFileStreamProcessor {
                framesToDecode = start
                if framesToDecode == 0 {
                    fillUsedFrames(framesCount: framesAdded)
-                    continue packetProccess
+                    continue packetProcess
                }
                prefillLocalBufferList(bufferList: localBufferList,
                                       dataOffset: 0,
@@ -475,9 +476,9 @@ final class AudioFileStreamProcessor {
                if status == AudioConvertStatus.done.rawValue {
                    fillUsedFrames(framesCount: framesAdded)
                    return
-                } else if status == AudioConvertStatus.proccessed.rawValue {
+                } else if status == AudioConvertStatus.processed.rawValue {
                    fillUsedFrames(framesCount: framesAdded)
-                    continue packetProccess
+                    continue packetProcess
                } else if status != 0 {
                    fileStreamCallback?(.raiseError(.codecError))
                    return
@@ -502,9 +503,9 @@ final class AudioFileStreamProcessor {
                if status == AudioConvertStatus.done.rawValue {
                    fillUsedFrames(framesCount: framesAdded)
                    return
-                } else if status == AudioConvertStatus.proccessed.rawValue {
+                } else if status == AudioConvertStatus.processed.rawValue {
                    fillUsedFrames(framesCount: framesAdded)
-                    continue packetProccess
+                    continue packetProcess
                } else if status != 0 {
                    fileStreamCallback?(.raiseError(.codecError))
                    return
@@ -545,8 +546,8 @@ final class AudioFileStreamProcessor {
    }

    @inline(__always)
-    private func updateProccessedPackets(inPacketDescriptions: UnsafeMutablePointer<AudioStreamPacketDescription>?,
-                                         inNumberPackets: UInt32)
+    private func updateProcessedPackets(inPacketDescriptions: UnsafeMutablePointer<AudioStreamPacketDescription>?,
+                                        inNumberPackets: UInt32)
    {
        guard let inPacketDescriptions = inPacketDescriptions else { return }
        guard let readingEntry = playerContext.audioReadingEntry else { return }
@@ -618,12 +619,12 @@ private func _converterCallback(inAudioConverter _: AudioConverterRef,
    ioNumberDataPackets.pointee = convertInfo.pointee.numberOfPackets
    convertInfo.pointee.done = true

-    return AudioConvertStatus.proccessed.rawValue
+    return AudioConvertStatus.processed.rawValue
 }

 // MARK: HardwareCodedClass method

-private func getHardwareCodecClassDescripition(formatId: UInt32, classDesc: UnsafeMutablePointer<AudioClassDescription>) -> Bool {
+private func getHardwareCodecClassDescription(formatId: UInt32, classDesc: UnsafeMutablePointer<AudioClassDescription>) -> Bool {
    #if os(iOS)
        var size: UInt32 = 0
        let formatIdSize = UInt32(MemoryLayout.size(ofValue: formatId))
@@ -0,0 +1,177 @@
+//
+//  Created by Dimitrios C on 19/05/2021.
+//  Copyright © 2021 Decimal. All rights reserved.
+//
+
+import AVFoundation
+
+///
+/// - parameter buffer: A buffer of audio captured from the output of an AVAudioNode.
+/// - parameter when: The time the buffer was captured.
+///
+public typealias FilterCallback = (_ buffer: AVAudioPCMBuffer,
+                                   _ when: AVAudioTime) -> Void
+
+/// A value type whose instances are used for frame filter
+/// - Note:
+/// The filter block will be called from a thread other than the main thread
+public struct FilterEntry: Equatable {
+    /// A string value indicating the name of the filter
+    public let name: String
+
+    /// A block in which you apply any filtering
+    public let filter: FilterCallback
+
+    public init(name: String, filter: @escaping FilterCallback) {
+        self.name = name
+        self.filter = filter
+    }
+
+    public static func == (lhs: FilterEntry, rhs: FilterEntry) -> Bool {
+        lhs.name == rhs.name
+    }
+}
+
+public protocol FrameFiltering {
+
+    /// A Boolean value indicating whether there are filter entries
+    var hasEntries: Bool { get }
+
+    /// Adds a filter entry at the end of the queue
+    /// - Parameter entry: An instance of `FilterEntry`
+    func add(entry: FilterEntry)
+
+    /// Adds a filter entry after the specified name of another entry
+    /// - Parameters:
+    ///   - entry: An instance of `FilterEntry`
+    ///   - named: The name of a previously added filter
+    func add(entry: FilterEntry, afterEntry named: String)
+
+    /// Adds a filter entry with the given parameters
+    /// - Parameters:
+    ///   - named: The name of the entry to be added
+    ///   - filter: The block for the filter hanlding
+    func add(entry named: String, filter: @escaping FilterCallback)
+
+    /// Adds a filter entry with the given parameters
+    /// - Parameters:
+    ///   - name: The name for the new entry
+    ///   - filterName: The name of a previously added filters
+    ///   - filter: The block for the filter hanlding
+    func add(entry named: String, after filterName: String, filter: @escaping FilterCallback)
+
+    /// Removes a filter entry
+    /// - Parameter entry: An instance of `FilterEntry` to be removed
+    func remove(entry: FilterEntry)
+
+    /// Attemps to remove a filter entry by its name
+    /// - Parameter named: A `String` representing the name of the filter entry
+    func remove(entry named: String)
+
+    /// Removes all filter entries
+    func removeAll()
+}
+
+final class FrameFilterProcessor: NSObject, FrameFiltering {
+
+    public var hasEntries: Bool {
+        lock.lock(); defer { lock.unlock() }
+        return !entries.isEmpty
+    }
+
+    private let lock = UnfairLock()
+    private let mixerNode: AVAudioMixerNode
+
+    private(set) var entries: [FilterEntry] = []
+
+    private var hasInstalledTap: Bool = false
+
+    init(mixerNode: AVAudioMixerNode) {
+        self.mixerNode = mixerNode
+    }
+
+    public func add(entry: FilterEntry) {
+        lock.lock(); defer { lock.unlock() }
+        entries.append(entry)
+        installTapIfNeeded()
+    }
+
+    public func add(entry: FilterEntry, afterEntry named: String) {
+        lock.lock(); defer { lock.unlock() }
+        guard let entryIndex = entries.firstIndex(where: { $0.name == named }) else {
+            return
+        }
+        if entryIndex.advanced(by: 1) > entries.count {
+            entries.append(entry)
+        } else {
+            entries.insert(entry, at: entryIndex + 1)
+        }
+        installTapIfNeeded()
+    }
+
+    public func add(entry named: String, filter: @escaping FilterCallback) {
+        lock.lock(); defer { lock.unlock() }
+        entries.append(FilterEntry(name: named, filter: filter))
+        installTapIfNeeded()
+    }
+
+    func add(entry named: String, after filterName: String, filter: @escaping FilterCallback) {
+        let entry = FilterEntry(name: named, filter: filter)
+        add(entry: entry, afterEntry: filterName)
+    }
+
+    public func remove(entry: FilterEntry) {
+        lock.lock(); defer { lock.unlock() }
+        guard let entryIndex = entries.firstIndex(where: { $0 == entry }) else {
+            return
+        }
+        entries.remove(at: entryIndex)
+        if entries.isEmpty {
+            removeTap()
+        }
+    }
+
+    public func remove(entry named: String) {
+        lock.lock(); defer { lock.unlock() }
+        guard let entryIndex = entries.firstIndex(where: { $0.name == named }) else {
+            return
+        }
+        entries.remove(at: entryIndex)
+        if entries.isEmpty {
+            removeTap()
+        }
+    }
+
+    public func removeAll() {
+        lock.lock(); defer { lock.unlock() }
+        entries.removeAll()
+        removeTap()
+    }
+
+    private func process(buffer: AVAudioPCMBuffer, when: AVAudioTime) {
+        lock.lock(); defer { lock.unlock() }
+        guard !entries.isEmpty else { return }
+        for entry in entries {
+            entry.filter(buffer, when)
+        }
+    }
+
+    private func installTapIfNeeded() {
+        guard !hasInstalledTap else { return }
+        hasInstalledTap = true
+        let format = mixerNode.outputFormat(forBus: 0)
+        mixerNode.installTap(onBus: 0, bufferSize: 1024, format: format) { [weak self] buffer, when in
+            guard let self = self else { return }
+            guard self.hasEntries else { return }
+            self.process(
+                buffer: buffer,
+                when: when
+            )
+        }
+    }
+
+    private func removeTap() {
+        hasInstalledTap = false
+        mixerNode.removeTap(onBus: 0)
+    }
+}
@@ -0,0 +1,92 @@
+//
+//  IcycastHeadersProcessor.swift
+//  AudioStreaming
+//
+//  Created by Dimitrios C on 14/02/2021.
+//  Copyright © 2021 Decimal. All rights reserved.
+//
+
+import Foundation
+
+/// ICY is built on HTTP some old servers might still send headers in the stream.
+/// From a server point of view, this should be considered deprecated and should not be used as it might break HTML5 compatibility.
+/// Although there are some servers still using this, this class will extract those headers from the stream
+///
+/// The format of the headers is as follows:
+/// ```
+/// =================================================================
+/// [ ICY 200 OK                                                    ]
+/// [ icy-mentaint: the number of bytes between 2 metadata chunks   ]
+/// [ icy-br: send the bitrate in kilobits per second               ]
+/// [ icy-genre: sends the genre                                    ]
+/// [ icy-name: sends the stream's name                             ]
+/// [ icy-url: is the URL of the radio station                      ]
+/// [ icy-pub: can be 1 or 0 to tell if it is listed or not         ]
+/// =================================================================
+/// ```
+
+final class IcycastHeadersProcessor {
+
+    private var icecastHeaders = Data(capacity: 1024)
+    private var searchComplete = false
+    private var iceHeaderAvailable = false
+
+    func reset() {
+        icecastHeaders = Data(capacity: 1024)
+        searchComplete = false
+        iceHeaderAvailable = false
+    }
+
+    @inline(__always)
+    func process(data: Data) -> (Data?, Data) {
+        let stopProcessingCheckOne: [UInt8] = Array("\n\n".utf8)
+        let stopProcessingCheckTwo: [UInt8] = Array("\r\n\r\n".utf8)
+        let icyPrefix: [UInt8] = Array("ICY ".utf8)
+        let httpPrefix: [UInt8] = Array("HTTP".utf8)
+        return data.withUnsafeBytes { buffer -> (Data?, Data) in
+            guard !buffer.isEmpty else { return (nil, data) }
+            var bytesRead = 0
+            let bytes = buffer.baseAddress!.assumingMemoryBound(to: UInt8.self)
+            // Read through the bytes and stop when our search is complete
+            // Since we don't know the amount of bytes to be processed
+            // we add each character up until we found on of the checks as defined above.
+            while bytesRead < buffer.count, !searchComplete {
+                let pointer = bytes + bytesRead
+                icecastHeaders.append(pointer, count: 1)
+
+                if icecastHeaders.count >= stopProcessingCheckOne.count {
+                    if icecastHeaders.suffix(stopProcessingCheckOne.count) == stopProcessingCheckOne {
+                        iceHeaderAvailable = true
+                        searchComplete = true
+                        break
+                    }
+                }
+
+                if icecastHeaders.count >= stopProcessingCheckTwo.count {
+                    if icecastHeaders.suffix(stopProcessingCheckTwo.count) == stopProcessingCheckTwo {
+                        iceHeaderAvailable = true
+                        searchComplete = true
+                        break
+                    }
+                }
+
+                if icecastHeaders.count >= icyPrefix.count {
+                    // in case the first 4 chars are not "ICY " nor "HTTP" then we stop the flow
+                    if icecastHeaders[..<icyPrefix.count].elementsEqual(icyPrefix) == false &&
+                        icecastHeaders[..<httpPrefix.count].elementsEqual(httpPrefix) == false {
+                        iceHeaderAvailable = false
+                        searchComplete = true
+                    }
+                }
+
+                bytesRead += 1
+            }
+            if !iceHeaderAvailable {
+                return (nil, data)
+            }
+            let extractedAudio = data[icecastHeaders.count...]
+            iceHeaderAvailable = false
+            return (icecastHeaders, extractedAudio)
+        }
+    }
+}
@@ -13,15 +13,15 @@ protocol MetadataStreamSource {
    var delegate: MetadataStreamSourceDelegate? { get set }

    /// Returns `true` when the stream header has indicated that we can proccess metadata, otherwise `false`.
-    var canProccessMetadata: Bool { get }
+    var canProcessMetadata: Bool { get }

    /// Assigns the metadata step of the metadata
    func metadataAvailable(step: Int)

-    /// Proccess the received data and extract the metadata if any, returns audio data only.
+    /// Process the received data and extract the metadata if any, returns audio data only.
    /// - parameter data: A `Data` object for parsing any metadata
    /// - returns: The extracted audio `Data`
-    func proccessMetadata(data: Data) -> Data
+    func processMetadata(data: Data) -> Data

    /// Resets the processor
    func reset()
@@ -44,7 +44,7 @@ protocol MetadataStreamSource {
 final class MetadataStreamProcessor: MetadataStreamSource {
    weak var delegate: MetadataStreamSourceDelegate?

-    var canProccessMetadata: Bool {
+    var canProcessMetadata: Bool {
        return metadataStep > 0
    }

@@ -73,10 +73,10 @@ final class MetadataStreamProcessor: MetadataStreamSource {
        audioDataBytesRead = 0
    }

-    // MARK: Proccess Metadata
+    // MARK: Process Metadata

    @inline(__always)
-    func proccessMetadata(data: Data) -> Data {
+    func processMetadata(data: Data) -> Data {
        data.withUnsafeBytes { buffer -> Data in
            guard !buffer.isEmpty else { return data }
            var audioData = Data()
@@ -14,7 +14,7 @@ struct HeaderField {
 }

 enum IcyHeaderField {
-    public static let icyMentaint = "icy-metaint"
+    public static let icyMetaint = "icy-metaint"
 }

 struct HTTPHeaderParserOutput {
@@ -39,7 +39,7 @@ struct HTTPHeaderParser: HTTPHeaderParsing {
    typealias Output = HTTPHeaderParserOutput?

    func parse(input: HTTPURLResponse) -> HTTPHeaderParserOutput? {
-        guard let headers = input.allHeaderFields as? [String: String], !headers.isEmpty else { return nil }
+        guard let headers = input.allHeaderFields as? [String: String], headers.count > 2 else { return nil }

        var typeId: UInt32 = 0
        if let contentType = input.mimeType {
@@ -64,7 +64,7 @@ struct HTTPHeaderParser: HTTPHeaderParsing {
        }

        var metadataStep = 0
-        if let icyMetaint = value(forHTTPHeaderField: IcyHeaderField.icyMentaint, in: input),
+        if let icyMetaint = value(forHTTPHeaderField: IcyHeaderField.icyMetaint, in: input),
           let intValue = Int(icyMetaint)
        {
            metadataStep = intValue
@@ -0,0 +1,34 @@
+//
+//  IcycastHeaderParser.swift
+//  AudioStreaming
+//
+//  Created by Dimitrios C on 14/02/2021.
+//  Copyright © 2021 Decimal. All rights reserved.
+//
+
+import Foundation
+
+struct IcycastHeaderParser: Parser {
+
+    func parse(input: Data) -> HTTPHeaderParserOutput? {
+
+        guard let icecastValue = String(data: input, encoding: .utf8) else {
+            return nil
+        }
+        let headers = icecastValue.components(separatedBy: CharacterSet(charactersIn: "\r\n"))
+        var result = [String: String]()
+        for header in headers where !header.isEmpty {
+            let values = header.split(separator: ":", maxSplits: 1, omittingEmptySubsequences: true)
+            if let key = values.first, let value = values.last {
+                result[String(key)] = String(value)
+            }
+        }
+        let metadataStep = Int(result[IcyHeaderField.icyMetaint] ?? "") ?? 0
+        let contentType = result[HeaderField.contentType.lowercased()] ?? "audio/mpeg"
+        let typeId = audioFileType(mimeType: contentType)
+
+        return HTTPHeaderParserOutput(fileLength: 0,
+                                      typeId: typeId,
+                                      metadataStep: metadataStep)
+    }
+}
@@ -18,7 +18,7 @@ struct MetadataParser: Parser {

    func parse(input: Data) -> MetadataOutput {
        guard let string = String(data: input, encoding: .utf8) else { return .failure(.unableToParse) }
-        // remove added bytes (zeros) and seperate the string on every ';' char
+        // remove added bytes (zeros) and separate the string on every ';' char
        let pairs = string.trimmingCharacters(in: CharacterSet(charactersIn: "\0")).components(separatedBy: ";")
        let temp: [String: String] = [:]
        let metadata = pairs.reduce(into: temp) { result, next in
@@ -18,19 +18,19 @@ class MetadataStreamProcessorTests: XCTestCase {
        let processor = MetadataStreamProcessor(parser: parser.eraseToAnyParser())

        // without calling `metadataAvailable(step:)` it should be false
-        XCTAssertFalse(processor.canProccessMetadata)
+        XCTAssertFalse(processor.canProcessMetadata)

        // calling `metadataAvailable(step:)` with zero
        processor.metadataAvailable(step: 0)

        // it should be false
-        XCTAssertFalse(processor.canProccessMetadata)
+        XCTAssertFalse(processor.canProcessMetadata)

        // calling `metadataAvailable(step:)` with greater zero
        processor.metadataAvailable(step: 1)

        // it should be true
-        XCTAssertTrue(processor.canProccessMetadata)
+        XCTAssertTrue(processor.canProcessMetadata)
    }

    func test_Processor_Outputs_Correct_Metadata_ForStep_WithEmptyMetadata() throws {
@@ -45,7 +45,7 @@ class MetadataStreamProcessorTests: XCTestCase {
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

-        let audio = processor.proccessMetadata(data: data)
+        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertTrue(metadataDelegateSpy.receivedMetadata.called)
@@ -64,7 +64,7 @@ class MetadataStreamProcessorTests: XCTestCase {
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

-        let audio = processor.proccessMetadata(data: data)
+        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertTrue(metadataDelegateSpy.receivedMetadata.called)
@@ -83,7 +83,7 @@ class MetadataStreamProcessorTests: XCTestCase {
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 8000)

-        let audio = processor.proccessMetadata(data: data)
+        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertTrue(metadataDelegateSpy.receivedMetadata.called)
@@ -106,7 +106,7 @@ class MetadataStreamProcessorTests: XCTestCase {
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

-        let audio = processor.proccessMetadata(data: data)
+        let audio = processor.processMetadata(data: data)
        XCTAssertFalse(audio.isEmpty)

        XCTAssertFalse(metadataDelegateSpy.receivedMetadata.called)
@@ -122,7 +122,7 @@ class MetadataStreamProcessorTests: XCTestCase {
        // this is the step value as received from the http headers
        processor.metadataAvailable(step: 16000)

-        let audio = processor.proccessMetadata(data: data)
+        let audio = processor.processMetadata(data: data)
        XCTAssertTrue(audio.isEmpty)

        XCTAssertFalse(metadataDelegateSpy.receivedMetadata.called)
@@ -34,7 +34,7 @@ class HTTPHeaderParserTests: XCTestCase {
        let headers: [String: String] =
            [HeaderField.contentLength: "1000",
             HeaderField.contentType: "audio/mp3",
-             IcyHeaderField.icyMentaint: "16000"]
+             IcyHeaderField.icyMetaint: "16000"]
        let httpURLResponse = HTTPURLResponse(url: URL(string: "www.google.com")!,
                                              statusCode: 200,
                                              httpVersion: "",
@@ -57,7 +57,7 @@ class HTTPHeaderParserTests: XCTestCase {
        let headers: [String: String] =
            [HeaderField.contentLength.lowercased(): "1000",
             HeaderField.contentType.lowercased(): "audio/mp3",
-             IcyHeaderField.icyMentaint.lowercased(): "16000"]
+             IcyHeaderField.icyMetaint.lowercased(): "16000"]
        let httpURLResponse = HTTPURLResponse(url: URL(string: "www.google.com")!,
                                              statusCode: 200,
                                              httpVersion: "",
@@ -3,7 +3,7 @@
 # AudioStreaming
 An AudioPlayer/Streaming library for iOS written in Swift, allows playback of online audio streaming, local file as well as gapless queueing.

-Under the hood `AudioStreaming` uses `AVAudioEngine` and `CoreAudio` for playback and provides an easy way of applying real-time [audio enhancements](https://developer.apple.com/documentation/avfoundation/audio_playback_recording_and_processing/avaudioengine/audio_units?language=swift).
+Under the hood `AudioStreaming` uses `AVAudioEngine` and `CoreAudio` for playback and provides an easy way of applying real-time [audio enhancements](https://developer.apple.com/documentation/avfaudio/audio_engine/audio_units).

 #### Supported audio
 - Online streaming (Shoutcast/ICY streams) with metadata parsing 
@@ -124,6 +124,41 @@ player.detachCustomAttachedNodes()

 The example project shows an example of adding a custom `AVAudioUnitEQ` node for adding equaliser to the `AudioPlayer`

+### Adding custom frame filter for recording and observation of audio data
+
+`AudioStreaming` allow for custom frame fliters to be added so that recording or other observation for audio that's playing.
+
+You add a frame filter by using the `AudioPlayer`'s property `frameFiltering`.
+
+```
+let player = AudioPlayer()
+let format = player.mainMixerNode.outputFormat(forBus: 0)
+
+let settings = [
+    AVFormatIDKey: kAudioFormatMPEG4AAC,
+    AVSampleRateKey: format.sampleRate,
+    AVNumberOfChannelsKey: format.channelCount
+] as [String : Any]
+
+var audioFile = try? AVAudioFile(
+        forWriting: outputUrl,
+        settings: settings,
+        commonFormat: format.commonFormat,
+        interleaved: format.isInterleaved)
+
+let record = FilterEntry(name: "record") { buffer, when in
+    try? audioFile?.write(from: buffer)
+}
+
+player.frameFiltering.add(entry: record)
+```
+See the `FrameFiltering` protocol for more ways of adding and removing frame filters. 
+The callback in which you observe a filter will be run on a thread other than the main thread. 
+
+Under the hood the concrete class for frame filters, `FrameFilterProcessor` installs a tap on the `mainMixerNode` of  `AVAudioEngine` in which all the added fitler will be called from.
+
+**Note** since the `mainMixerNode` is publicly exposed extra care should be taken to not install a tap directly and also use frame filters, this result in an exception because only one tap can be installed on an output node, as per Apple's documention. 
+
 # Installation

 ### Cocoapods
Author	SHA1	Message	Date
dimitris-c	0758c14909	Bumping version	2021-12-06 20:01:12 +02:00
Dimitris C	03c6a7692c	Fixes an issue where the memory is not released after paused audio (#33 )	2021-12-06 19:58:50 +02:00
dimitris-c	02a3606185	Fixes unit tests	2021-10-05 18:55:34 +03:00
Dimitris C	7e45a7b2f5	Removes unneeded DispatchTimerSource (#32 ) Correct Spelling issues Fix an issue in RemoteAudioSource when icycast headers are not available	2021-10-05 18:32:55 +03:00
Dimitris C	30b4189778	Bumping version (#30 )	2021-09-07 15:47:59 +03:00
Dimitris C	8bdc2a64f7	Fixes a memory leak issue in RemoteAudioSource (#29 )	2021-09-07 15:36:51 +03:00
Dimitris C	65de9d90c0	Version bump (#19 ) * Bumps version * Bumps version Co-authored-by: Dimitrios C <dimitrisc@DimitrisC-Macbook-Pro.local>	2021-05-25 00:01:31 +03:00
Dimitris C	217a88f171	Adds frame filters to allow recording, monitoring, and observation of audio (#18 ) * Adds frame filters feature * nit * Updates Readme file Co-authored-by: Dimitrios C <dimitrisc@DimitrisC-Macbook-Pro.local>	2021-05-24 23:58:16 +03:00
Dimitrios C	566dc86f3f	Bumps version	2021-05-18 23:57:01 +03:00
Dimitrios C	d8aa58525c	Makes AudioPlayer an open class Exposes AudioEngine’s mainMixerNode Added missing documentation	2021-05-18 23:54:43 +03:00
Dimitris C	8197db0016	Update README.md	2021-04-12 13:10:44 +03:00
Dimitris C	c2aee1669b	Bump version (#17 ) Co-authored-by: Dimitrios C <dimitrisc@DimitrisC-Macbook-Pro.local>	2021-03-22 12:15:42 +02:00
Mushthak Ebrahim	334be32bf9	Fix header not get passed into method (#16 )	2021-03-02 18:15:26 +02:00
Dimitris C	a2da46f85b	Bump version (#15 )	2021-02-14 16:37:49 +02:00
Dimitris C	aca69debd1	Adds support for Shoutcast headers in audio stream (#14 ) * Adds support for Shoutcast headers in audio stream * Renames proccessIcecastHeaders to process(data: * Updates comment on IcycastHeadersProcessor	2021-02-14 16:33:37 +02:00