Apple

I am in the process of converting an old existing project to use AVFoundation APIs. I have two goals

1) Read the data into a Int16, interleaved format buffer

2) Manipulate the data in the buffer directly (not realtime)

In testing, I found that I am getting “error -10868”, however I haven’t been able to figure out what is wrong.

The buffer is created, there is no error but I am unable to play the audio. How do I overcome this issue?

My second question is how do I access the buffer directly or more specifically the stereo channels. When I was using CoreAudio APIs (pre-Swift), I understood but now I’m lost. In coreaudio, I previously used an interleaved buffer. Would someone be kind enough to show me how I could access the channels in both interleaved and non-interleaved.

My test input file is an Apple Lossless Compression file if that matters.

Thank you,

Test result

bufferExists = true

readErr = nil

audioFileBuffer.format = <AVAudioFormat 0x6080008968a0: 2 ch, 44100 Hz, Int16, inter>

File URL: Optional("file:///Users/wedwards/Desktop/tempAudioOutput.m4a")

File format: <AVAudioFormat 0x608000892ed0: 2 ch, 44100 Hz, 'alac' (0x00000001) from 16-bit source, 4096 frames/packet>

File format descr: <AVAudioFormat 0x608000892ed0: 2 ch, 44100 Hz, 'alac' (0x00000001) from 16-bit source, 4096 frames/packet>

Processing format: <AVAudioFormat 0x60800089dce0: 2 ch, 44100 Hz, Int16, inter>

Length: 184320 frames, 4.17959183673469 seconds

2015-04-13 15:47:36.911 SWIFT - Manipulate Audio Data[2993:250205] 15:47:36.911 ERROR: AVAudioNode.mm:521: AUSetFormat: error -10868

2015-04-13 15:47:36.912 SWIFT - Manipulate Audio Data[2993:250205] error -10868

import Foundation

import AVFoundation

import Cocoa

var audioEngine : AVAudioEngine = AVAudioEngine()

var audioFilePlayer: AVAudioPlayerNode = AVAudioPlayerNode()

func displayAudioFormatInfo( fileURL: NSURL, audioFile: AVAudioFile)

{

var fileLength = AVAudioFramePosition(audioFile.length)

var lengthInSeconds = Float64(fileLength) / audioFile.fileFormat.sampleRate

println("File URL: \(fileURL.absoluteString)")

println("File format: \(audioFile.fileFormat)")

println("File format descr: \(audioFile.fileFormat.description)")

println("Processing format: \(audioFile.processingFormat.description)")

println("Length: \(fileLength) frames, \(lengthInSeconds) seconds")

}

func readAudioDataTEST( fileURL: NSURL )

{

var readErr : NSError? = nil

var isInterleaved = true

var format = AVAudioCommonFormat.PCMFormatInt16 // the desired working format

let audioFile = AVAudioFile(forReading: fileURL, commonFormat: format, interleaved: isInterleaved, error: nil)

let audioFormat = AVAudioFormat(commonFormat: AVAudioCommonFormat.PCMFormatInt16, sampleRate: 44100.0, channels:AVAudioChannelCount(2), interleaved: true)

let audioFrameCount = AVAudioFrameCount(audioFile.length)

let audioFileBuffer = AVAudioPCMBuffer(PCMFormat: audioFormat, frameCapacity: audioFrameCount)

var bufferExists = audioFile.readIntoBuffer(audioFileBuffer, error: &readErr)

println("bufferExists = \(bufferExists)")

println("readErr = \(readErr)")

println("audioFileBuffer.format = \(audioFileBuffer.format)")

displayAudioFormatInfo( fileURL, audioFile )

var mainMixer = audioEngine.mainMixerNode

audioEngine.attachNode(audioFilePlayer)

audioEngine.connect(audioFilePlayer, to: mainMixer, format: audioFileBuffer.format)

audioEngine.startAndReturnError(nil)

audioFilePlayer.play()

audioFilePlayer.scheduleBuffer(audioFileBuffer, atTime: nil, options: nil, completionHandler: nil)

}

func getUrlFromNavDialog() -> NSURL?{

var openPanel = NSOpenPanel()

var url: NSURL?

openPanel.allowsMultipleSelection = false

openPanel.canChooseDirectories = false

openPanel.canCreateDirectories = false

openPanel.canChooseFiles = true

openPanel.runModal()

return openPanel.URL?

}

var fileURL = getUrlFromNavDialog()

if (fileURL != nil ) { readAudioData(fileURL!) }