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,
W.
/*
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!) }
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