CODEWITHSUNDEEP
swiftios8avaudiopcmbufferavaudiofileavaudioplayernode
Bick
Bick

Reputation: 763

how to play sound with AVAudioPCMBuffer

I Cannot play sound with AVAudioPCMBuffer (though I could play with AVAudioFile). I got this error.

ERROR: AVAudioBuffer.mm:169: -[AVAudioPCMBuffer initWithPCMFormat:frameCapacity:]: required condition is false: isCommonFormat

here is my code below, and I'd really appreciate for your help.

import UIKit
import AVFoundation

class ViewController: UIViewController {

let audioEngine: AVAudioEngine = AVAudioEngine()
let audioFilePlayer: AVAudioPlayerNode = AVAudioPlayerNode()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    audioEngine.attachNode(audioFilePlayer)

    let filePath: String = NSBundle.mainBundle().pathForResource("test", ofType: "mp3")!
    let fileURL: NSURL = NSURL(fileURLWithPath: filePath)!
    let audioFile = AVAudioFile(forReading: fileURL, error: nil)
    let audioFormat = audioFile.fileFormat
    let audioFrameCount = UInt32(audioFile.length)
    let audioFileBuffer = AVAudioPCMBuffer(PCMFormat: audioFormat, frameCapacity: audioFrameCount)

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

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

    var engineError: NSError?
    audioEngine.startAndReturnError(&engineError)

    audioFilePlayer.play()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

Upvotes: 14

Views: 12019

Answers (5)

Duke Caesar
Duke Caesar

Reputation: 99

Instead of calling audioFile.fileFormat, you should use audioFile.processingFormat as the parameter for AVAudioPCMBuffer contructor.

let buffer = AVAudioPCMBuffer(pcmFormat: audioFile.processingFormat,
                                            frameCapacity: bufferCapacity)

Upvotes: 0

dengST30
dengST30

Reputation: 4037

update @Bick's code to Swift 5.3

the code logic is easy to get

  • Firstly, prepare the data

create an empty AVAudioPCMBuffer, then fill audio data in it.

  • Secondly, connect the nodes, and use the data to play

    import UIKit
import AVFoundation

  class ViewControllerX: UIViewController {

    var audioEngine = AVAudioEngine()
    var audioFilePlayer = AVAudioPlayerNode()

    override func viewDidLoad() {
      super.viewDidLoad()

      // prepare the data
      guard let filePath = Bundle.main.path(forResource: "test", ofType: "mp3") else{ return }

      print("\(filePath)")
      let fileURL = URL(fileURLWithPath: filePath)
      do {
          let audioFile = try AVAudioFile(forReading: fileURL)

          let audioFormat = audioFile.processingFormat
          let audioFrameCount = UInt32(audioFile.length)
          guard let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: audioFormat, frameCapacity: audioFrameCount) else{ return }
          try audioFile.read(into: audioFileBuffer)

          // connect the nodes, and use the data to play
          let mainMixer = audioEngine.mainMixerNode
          audioEngine.attach(audioFilePlayer)
          audioEngine.connect(audioFilePlayer, to: mainMixer, format: audioFileBuffer.format)

          try audioEngine.start()

          audioFilePlayer.play()
          audioFilePlayer.scheduleBuffer(audioFileBuffer, completionHandler: nil)

      } catch {
          print(error)
      }

    }
}

Upvotes: 1

Andrew Hodel
Andrew Hodel

Reputation: 35

When using an AVAudioPCMBuffer() you'll get strange errors if you try and use a pcmFormat that's not mixer.outputFormat(forBus: 0)

It will not accept mono channel formats, it will complain about mismatches between the mixer's output format and your format even if you've described them exactly the same and it won't produce errors that explain exactly what the problem is.

Upvotes: 4

Bob McCune
Bob McCune

Reputation: 41

The problem is you're setting the format of your PCM buffer to a non-PCM format. Therefore, you need to create your AVAudioPCMBuffer with the AVAudioFile's processingFormat.

Upvotes: 4

Bick
Bick

Reputation: 763

just let me share, this worked somehow, though I don't understand fully.

import UIKit
import AVFoundation

class ViewController: UIViewController {

var audioEngine: AVAudioEngine = AVAudioEngine()
var audioFilePlayer: AVAudioPlayerNode = AVAudioPlayerNode()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.


    let filePath: String = NSBundle.mainBundle().pathForResource("test", ofType: "mp3")!
    println("\(filePath)")
    let fileURL: NSURL = NSURL(fileURLWithPath: filePath)!
    let audioFile = AVAudioFile(forReading: fileURL, error: nil)
    let audioFormat = audioFile.processingFormat
    let audioFrameCount = UInt32(audioFile.length)
    let audioFileBuffer = AVAudioPCMBuffer(PCMFormat: audioFormat, frameCapacity: audioFrameCount)
    audioFile.readIntoBuffer(audioFileBuffer, error: nil)

    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)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

Upvotes: 8

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