diff --git a/Sources/Media/IOAudioUnit.swift b/Sources/Media/IOAudioUnit.swift
index 7b06db778..9bc7adf97 100644
--- a/Sources/Media/IOAudioUnit.swift
+++ b/Sources/Media/IOAudioUnit.swift
@@ -7,11 +7,6 @@ import SwiftPMSupport
 final class IOAudioUnit: NSObject, IOUnit {
     typealias FormatDescription = CMAudioFormatDescription
 
-    lazy var codec: AudioCodec = {
-        var codec = AudioCodec()
-        codec.lockQueue = lockQueue
-        return codec
-    }()
     let lockQueue = DispatchQueue(label: "com.haishinkit.HaishinKit.AudioIOComponent.lock")
     var soundTransform: SoundTransform = .init() {
         didSet {
@@ -39,7 +34,15 @@ final class IOAudioUnit: NSObject, IOUnit {
     var outputFormat: FormatDescription? {
         return codec.outputFormat?.formatDescription
     }
+    var inputBuffer: AVAudioBuffer? {
+        return codec.inputBuffer
+    }
     private(set) var presentationTimeStamp: CMTime = .invalid
+    private lazy var codec: AudioCodec = {
+        var codec = AudioCodec()
+        codec.lockQueue = lockQueue
+        return codec
+    }()
     private lazy var resampler: IOAudioResampler<IOAudioUnit> = {
         var resampler = IOAudioResampler<IOAudioUnit>()
         resampler.delegate = self
@@ -90,6 +93,26 @@ final class IOAudioUnit: NSObject, IOUnit {
             codec.appendSampleBuffer(sampleBuffer)
         }
     }
+
+    func appendAudioBuffer(_ audioBuffer: AVAudioBuffer, presentationTimeStamp: CMTime) {
+        codec.appendAudioBuffer(audioBuffer, presentationTimeStamp: presentationTimeStamp)
+    }
+
+    func setAudioStreamBasicDescription(_ audioStreamBasicDescription: AudioStreamBasicDescription?) {
+        guard var audioStreamBasicDescription else {
+            return
+        }
+        let status = CMAudioFormatDescriptionCreate(
+            allocator: kCFAllocatorDefault,
+            asbd: &audioStreamBasicDescription,
+            layoutSize: 0,
+            layout: nil,
+            magicCookieSize: 0,
+            magicCookie: nil,
+            extensions: nil,
+            formatDescriptionOut: &inputFormat
+        )
+    }
 }
 
 extension IOAudioUnit: IOUnitEncoding {
@@ -108,6 +131,7 @@ extension IOAudioUnit: IOUnitEncoding {
 extension IOAudioUnit: IOUnitDecoding {
     // MARK: IOUnitDecoding
     func startDecoding() {
+        codec.settings.format = .pcm
         if let playerNode = mixer?.mediaLink.playerNode {
             mixer?.audioEngine?.attach(playerNode)
         }
diff --git a/Sources/Media/IOMixer.swift b/Sources/Media/IOMixer.swift
index 711cde671..fccee2711 100644
--- a/Sources/Media/IOMixer.swift
+++ b/Sources/Media/IOMixer.swift
@@ -24,12 +24,6 @@ public final class IOMixer {
         return AVAudioEngine()
     }
 
-    enum ReadyState {
-        case standby
-        case encoding
-        case decoding
-    }
-
     public var hasVideo: Bool {
         get {
             mediaLink.hasVideo
@@ -200,7 +194,6 @@ public final class IOMixer {
     }
     #endif
 
-    private var readyState: ReadyState = .standby
     private(set) lazy var audioEngine: AVAudioEngine? = {
         return IOMixer.audioEngineHolder.retain()
     }()
@@ -247,46 +240,30 @@ public final class IOMixer {
 extension IOMixer: IOUnitEncoding {
     /// Starts encoding for video and audio data.
     public func startEncoding(_ delegate: any AVCodecDelegate) {
-        guard readyState == .standby else {
-            return
-        }
-        readyState = .encoding
         videoIO.startEncoding(delegate)
         audioIO.startEncoding(delegate)
     }
 
     /// Stop encoding.
     public func stopEncoding() {
-        guard readyState == .encoding else {
-            return
-        }
         videoIO.stopEncoding()
         audioIO.stopEncoding()
-        readyState = .standby
     }
 }
 
 extension IOMixer: IOUnitDecoding {
     /// Starts decoding for video and audio data.
     public func startDecoding() {
-        guard readyState == .standby else {
-            return
-        }
         audioIO.startDecoding()
         videoIO.startDecoding()
         mediaLink.startRunning()
-        readyState = .decoding
     }
 
     /// Stop decoding.
     public func stopDecoding() {
-        guard readyState == .decoding else {
-            return
-        }
         mediaLink.stopRunning()
         audioIO.stopDecoding()
         videoIO.stopDecoding()
-        readyState = .standby
     }
 }
 
@@ -375,8 +352,8 @@ extension IOMixer: Running {
             let isMultiCamSupported = true
             #endif
             guard let device = error.device, let format = device.videoFormat(
-                width: sessionPreset.width ?? Int32(videoIO.codec.settings.videoSize.width),
-                height: sessionPreset.height ?? Int32(videoIO.codec.settings.videoSize.height),
+                width: sessionPreset.width ?? Int32(videoIO.settings.videoSize.width),
+                height: sessionPreset.height ?? Int32(videoIO.settings.videoSize.height),
                 frameRate: videoIO.frameRate,
                 isMultiCamSupported: isMultiCamSupported
             ), device.activeFormat != format else {
diff --git a/Sources/Media/IOVideoUnit.swift b/Sources/Media/IOVideoUnit.swift
index 8c3972dc1..3b309d987 100644
--- a/Sources/Media/IOVideoUnit.swift
+++ b/Sources/Media/IOVideoUnit.swift
@@ -17,11 +17,6 @@ final class IOVideoUnit: NSObject, IOUnit {
         }
     }
     var multiCamCaptureSettings: MultiCamCaptureSettings = .default
-    lazy var codec: VideoCodec = {
-        var codec = VideoCodec()
-        codec.lockQueue = lockQueue
-        return codec
-    }()
     weak var mixer: IOMixer?
     var muted: Bool {
         get {
@@ -31,7 +26,14 @@ final class IOVideoUnit: NSObject, IOUnit {
             videoMixer.muted = newValue
         }
     }
-
+    var settings: VideoCodecSettings {
+        get {
+            return codec.settings
+        }
+        set {
+            codec.settings = newValue
+        }
+    }
     #if os(iOS) || os(macOS) || os(tvOS)
     var frameRate = IOMixer.defaultFrameRate {
         didSet {
@@ -111,6 +113,11 @@ final class IOVideoUnit: NSObject, IOUnit {
         videoMixer.delegate = self
         return videoMixer
     }()
+    private lazy var codec: VideoCodec = {
+        var codec = VideoCodec()
+        codec.lockQueue = lockQueue
+        return codec
+    }()
 
     deinit {
         if Thread.isMainThread {
diff --git a/Sources/Net/NetStream.swift b/Sources/Net/NetStream.swift
index 0979a7184..c5516a9d7 100644
--- a/Sources/Net/NetStream.swift
+++ b/Sources/Net/NetStream.swift
@@ -171,10 +171,10 @@ open class NetStream: NSObject {
     /// Specifies the video compression properties.
     public var videoSettings: VideoCodecSettings {
         get {
-            mixer.videoIO.codec.settings
+            mixer.videoIO.settings
         }
         set {
-            mixer.videoIO.codec.settings = newValue
+            mixer.videoIO.settings = newValue
         }
     }
 
diff --git a/Sources/RTMP/RTMPConnection.swift b/Sources/RTMP/RTMPConnection.swift
index cd96c8954..9472dbdf0 100644
--- a/Sources/RTMP/RTMPConnection.swift
+++ b/Sources/RTMP/RTMPConnection.swift
@@ -311,7 +311,7 @@ public class RTMPConnection: EventDispatcher {
         var outputBufferSize: Int = 0
         for stream in streams {
             // in bytes.
-            outputBufferSize += (Int(stream.mixer.videoIO.codec.settings.bitRate) + stream.mixer.audioIO.codec.settings.bitRate) / 8
+            outputBufferSize += (Int(stream.mixer.videoIO.settings.bitRate) + stream.mixer.audioIO.settings.bitRate) / 8
         }
         if socket.outputBufferSize < outputBufferSize {
             socket.outputBufferSize = outputBufferSize
diff --git a/Sources/RTMP/RTMPMessage.swift b/Sources/RTMP/RTMPMessage.swift
index 989c9d889..0d4b18f76 100644
--- a/Sources/RTMP/RTMPMessage.swift
+++ b/Sources/RTMP/RTMPMessage.swift
@@ -586,15 +586,13 @@ final class RTMPAudioMessage: RTMPMessage {
         switch payload[1] {
         case FLVAACPacketType.seq.rawValue:
             let config = AudioSpecificConfig(bytes: [UInt8](payload[codec.headerSize..<payload.count]))
-            stream.mixer.audioIO.codec.settings.format = .pcm
-            stream.mixer.audioIO.codec.inSourceFormat = config?.audioStreamBasicDescription()
+            stream.mixer.audioIO.setAudioStreamBasicDescription(config?.audioStreamBasicDescription())
         case FLVAACPacketType.raw.rawValue:
-            if stream.mixer.audioIO.codec.inSourceFormat == nil {
-                stream.mixer.audioIO.codec.settings.format = .pcm
-                stream.mixer.audioIO.codec.inSourceFormat = makeAudioStreamBasicDescription()
+            if stream.mixer.audioIO.inputFormat == nil {
+                stream.mixer.audioIO.setAudioStreamBasicDescription(makeAudioStreamBasicDescription())
             }
             if let audioBuffer = makeAudioBuffer(stream) {
-                stream.mixer.audioIO.codec.appendAudioBuffer(audioBuffer, presentationTimeStamp: CMTime(seconds: stream.audioTimestamp / 1000, preferredTimescale: 1000))
+                stream.mixer.audioIO.appendAudioBuffer(audioBuffer, presentationTimeStamp: CMTime(seconds: stream.audioTimestamp / 1000, preferredTimescale: 1000))
             }
         default:
             break
@@ -603,7 +601,7 @@ final class RTMPAudioMessage: RTMPMessage {
 
     private func makeAudioBuffer(_ stream: RTMPStream) -> AVAudioBuffer? {
         return payload.withUnsafeMutableBytes { (buffer: UnsafeMutableRawBufferPointer) -> AVAudioBuffer? in
-            guard let baseAddress = buffer.baseAddress, let buffer = stream.mixer.audioIO.codec.inputBuffer as? AVAudioCompressedBuffer else {
+            guard let baseAddress = buffer.baseAddress, let buffer = stream.mixer.audioIO.inputBuffer as? AVAudioCompressedBuffer else {
                 return nil
             }
             let byteCount = payload.count - codec.headerSize
@@ -653,7 +651,7 @@ final class RTMPVideoMessage: RTMPMessage {
                 makeFormatDescription(stream, format: .h264)
             case FLVAVCPacketType.nal.rawValue:
                 if let sampleBuffer = makeSampleBuffer(stream, type: type, offset: 0) {
-                    stream.mixer.videoIO.codec.appendSampleBuffer(sampleBuffer)
+                    stream.mixer.videoIO.appendSampleBuffer(sampleBuffer)
                 }
             default:
                 break
@@ -668,7 +666,7 @@ final class RTMPVideoMessage: RTMPMessage {
                 makeFormatDescription(stream, format: .hevc)
             case FLVVideoPacketType.codedFrames.rawValue:
                 if let sampleBuffer = makeSampleBuffer(stream, type: type, offset: 3) {
-                    stream.mixer.videoIO.codec.appendSampleBuffer(sampleBuffer)
+                    stream.mixer.videoIO.appendSampleBuffer(sampleBuffer)
                 }
             default:
                 break