Hi all, I'm using AVAudioEngine to play multiple nodes at various times (like GarageBand for example). So far I managed to play the various files at the right time using this code : DispatchQueue.global(qos: .background).async {             AudioManager.instance.audioEngine.attach(AudioManager.instance.mixer)             AudioManager.instance.audioEngine.connect(AudioManager.instance.mixer, to: AudioManager.instance.audioEngine.outputNode, format: nil)           // !important - start the engine *before* setting up the player nodes           try! AudioManager.instance.audioEngine.start()                      for audioFile in data {             // Create and attach the audioPlayer node for this file             let audioPlayer = AVAudioPlayerNode()             AudioManager.instance.audioEngine.attach(audioPlayer)             AudioManager.instance.nodes.append(audioPlayer)             // Notice the output is the mixer in this case             AudioManager.instance.audioEngine.connect(audioPlayer, to: AudioManager.instance.mixer, format: nil)             let fileUrl = audioFile.audio.fileUrl             if let file : AVAudioFile = try? AVAudioFile.init(forReading: fileUrl) {                 let time = audioFile.start > 0 ? AudioManager.instance.secondsToAVAudioTime(hostTime: mach_absolute_time(), time: Double(audioFile.start / CGFloat.secondsToPoints)) : nil                 audioPlayer.scheduleFile(file, at: time, completionHandler: nil)                 audioPlayer.play(at: time)             }           }         } Basically my data object contains struct that have a reference to an audio fileURL and the startPosition at which it should begin. That works great. now I would like to export all these tracks mixed into a single file and save it to the Document's directory of the user. How can I achieve this? Thanks for your help.

I have an AVMutableAudioMix and use MTAudioProcessingTap to process the audio data.But After I pass the buffer to AVAudioEngine and to render it with renderOffline,the audio has no any effects...How can I do it? Any idea? Here is the code for MTAudioProcessingTapProcessCallback var callback = MTAudioProcessingTapCallbacks(version: kMTAudioProcessingTapCallbacksVersion_0, clientInfo:UnsafeMutableRawPointer(Unmanaged.passUnretained(self.engine).toOpaque()), init: tapInit, finalize: tapFinalize, prepare: tapPrepare, unprepare: tapUnprepare) { tap, numberFrames, flags, bufferListInOut, numberFramesOut, flagsOut in                       guard MTAudioProcessingTapGetSourceAudio(tap, numberFrames, bufferListInOut, flagsOut, nil, numberFramesOut) == noErr else {         preconditionFailure()       }       let storage = MTAudioProcessingTapGetStorage(tap)       let engine = Unmanaged<Engine>.fromOpaque(storage).takeUnretainedValue()       // render the audio with effect       engine.render(bufferPtr: bufferListInOut,numberOfFrames: numberFrames)     } And here is the Engine code class Engine {   let engine = AVAudioEngine()       let player = AVAudioPlayerNode()   let pitchEffect = AVAudioUnitTimePitch()   let reverbEffect = AVAudioUnitReverb()   let rateEffect = AVAudioUnitVarispeed()   let volumeEffect = AVAudioUnitEQ()   let format = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: 44100, channels: 2, interleaved: false)!   init() {     engine.attach(player)     engine.attach(pitchEffect)     engine.attach(reverbEffect)     engine.attach(rateEffect)     engine.attach(volumeEffect)           engine.connect(player, to: pitchEffect, format: format)     engine.connect(pitchEffect, to: reverbEffect, format: format)     engine.connect(reverbEffect, to: rateEffect, format: format)     engine.connect(rateEffect, to: volumeEffect, format: format)     engine.connect(volumeEffect, to: engine.mainMixerNode, format: format)           try! engine.enableManualRenderingMode(.offline, format: format, maximumFrameCount: 4096)           reverbEffect.loadFactoryPreset(AVAudioUnitReverbPreset.largeRoom2)     reverbEffect.wetDryMix = 100     pitchEffect.pitch = 2100           try! engine.start()     player.play()   }       func render(bufferPtr:UnsafeMutablePointer<AudioBufferList>,numberOfFrames:CMItemCount) {     let buffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 4096)!     buffer.frameLength = AVAudioFrameCount(numberOfFrames)     buffer.mutableAudioBufferList.pointee = bufferPtr.pointee     self.player.scheduleBuffer(buffer) {       try! self.engine.renderOffline(AVAudioFrameCount(numberOfFrames), to: buffer)     }   } }

I have a kind of trivial request, I need to seek sound playback. The problem is I don't have a local sound file, I got a pointer to the sound instead (as well as other params), from (my internal) native lib. There is a method that I use in order to convert UnsafeRawPointer to AVAudioPCMBuffer ... var byteCount: Int32 = 0       var buffer: UnsafeMutableRawPointer?               defer {         buffer?.deallocate()         buffer = nil       }               if audioReader?.getAudioByteData(byteCount: &byteCount, data: &buffer) ?? false && buffer != nil {         let audioFormat = AVAudioFormat(standardFormatWithSampleRate: Double(audioSampleRate), channels: AVAudioChannelCount(audioChannels))!         if let pcmBuf = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: AVAudioFrameCount(byteCount)) {           let monoChannel = pcmBuf.floatChannelData![0]           pcmFloatData = [Float](repeating: 0.0, count: Int(byteCount))                       //>>> Convert UnsafeMutableRawPointer to [Int8] array           let int16Ptr: UnsafeMutablePointer<Int16> = buffer!.bindMemory(to: Int16.self, capacity: Int(byteCount))           let int16Buffer: UnsafeBufferPointer<Int16> = UnsafeBufferPointer(start: int16Ptr, count: Int(byteCount) / MemoryLayout<Int16>.size)           let int16Arr: [Int16] = Array(int16Buffer)           //<<<                       // Int16 ranges from -32768 to 32767 -- we want to convert and scale these to Float values between -1.0 and 1.0           var scale = Float(Int16.max) + 1.0           vDSP_vflt16(int16Arr, 1, &pcmFloatData[0], 1, vDSP_Length(int16Arr.count)) // Int16 to Float           vDSP_vsdiv(pcmFloatData, 1, &scale, &pcmFloatData[0], 1, vDSP_Length(int16Arr.count)) // divide by scale              memcpy(monoChannel, pcmFloatData, MemoryLayout<Float>.size * Int(int16Arr.count))           pcmBuf.frameLength = UInt32(int16Arr.count)                       usagePlayer.setupAudioEngine(with: audioFormat)           audioClip = pcmBuf         }       } ... So, at the end of the method, you can see this line audioClip = pcmBuf, where the prepared pcmBuf is pass to the local variable. Then, what I need is just to start it like this ... /*player is AVAudioPlayerNode*/ player.scheduleBuffer(buf, at: nil, options: .loops) player.play() ... and that is it, now I can hear the sound. But let's say I need to seek forward in 10 sec, in order to do this I need stop() the player node, set a new AVAudioPCMBuffer but this time with an offset of 10 sec. The problem is there is no method for offset, nor from the player node side nor AVAudioPCMBuffer. For example, if I would work with a file (instead of a buffer), I could use this method ... player.scheduleSegment(         file,         startingFrame: seekFrame,         frameCount: frameCount,         at: nil       ) ... There at least you can use startingFrame: seekFrame and frameCount: frameCount params. But in my case I don't use file I use buffer and the problem is that - there is no such params for buffer implementation. Looks like I can't implement seek logic if I use AVAudioPCMBuffer. What am I doing wrong?

I want to create a sort of soundscape in surround sound. Imagine something along the lines of the user can place the sound of a waterfall to their front right and the sound of frogs croaking to their left etc. etc. I have an AVAudioEngine playing a number of AVAudioPlayerNodes. I'm using AVAudioEnvironmentNode to simulate the positioning of these. The position seems to work correctly. However, I'd like these to work with head tracking so if the user moves their head the sounds from the players move accordingly. I can't figure out for to do it or find any docs on the subject. Is it possible to make AVAudioEngine output surround sound and if it can would the tracking just work automagically the same as it does when playing surround sound content using AVPlayerItem. If not is the only way to achieve this effect to use CMHeadphonemotionmanager and manually move the listener AVAudioEnvironmentNode listener around?

Using AVAudioEngine with an AVAudioPlayerNode which plays stereo sound works perfectly. I even understand that turning setVoiceProcessingEnabled on the inputNode turns the sound mono. But after I stop the session and the engine, and turn voice processing off, the sound remains mono. This issue is only present with the built in speakers. This is what the I/O formats of the nodes look like before and after the voiceProcessing on-off: Before: mainMixer input<AVAudioFormat 0x281896580: 2 ch, 44100 Hz, Float32, non-inter> mainMixer output<AVAudioFormat 0x2818919f0: 2 ch, 44100 Hz, Float32, non-inter> outputNode input<AVAudioFormat 0x281891cc0: 2 ch, 44100 Hz, Float32, non-inter> outputNode output<AVAudioFormat 0x281891770: 2 ch, 44100 Hz, Float32, non-inter> After: mainMixer input<AVAudioFormat 0x2818acaf0: 2 ch, 44100 Hz, Float32, non-inter> mainMixer output<AVAudioFormat 0x2818acaa0: 1 ch, 44100 Hz, Float32> outputNode input<AVAudioFormat 0x281898820: 1 ch, 44100 Hz, Float32> outputNode output<AVAudioFormat 0x2818958b0: 2 ch, 44100 Hz, Float32, non-inter> Sadly just changing the connection type does not solve anything, I already tried that with (this solves the stereo issue on headphones, but not on built in speakers): let format = AVAudioFormat(standardFormatWithSampleRate: 48000, channels: 2)! audioEngine.connect(audioEngine.mainMixerNode, to: audioEngine.outputNode, format: format)

I'm trying to understand the difference between the use of an AVAudioSinkNode v.s installTap() on an AVAudioNode. In "WWDC 510 - Whats new in core audio" https://developer.apple.com/videos/play/wwdc2019/510, the presenter states that AVAudioSinkNode works in a realtime context (better for VOIP, for example) where as installTap() on an AVAudioNode does not. It's unclear to me why one is better to use over the other. Why is AVAudioSinkNode better for realtime apps over using installTap()??