CODEWITHSUNDEEP
swiftmacosavfoundationavaudioengine
fractor
fractor

Reputation: 1650

AVAudioEngine mainMixerNode pan not working

I have the following method that plays a file.

let filePath = "/Users/fractor/Desktop/TestFile.mp3"
var file : AVAudioFile?
var audioEngine = AVAudioEngine()
var playerNode = AVAudioPlayerNode()

@IBAction func play(_ sender: Any) {

    do {
        file = try AVAudioFile(forReading: URL(fileURLWithPath: filePath))
    } catch let error {
        print(error.localizedDescription)
        return
    }

    audioEngine.attach(playerNode)
    audioEngine.connect(playerNode, to: audioEngine.mainMixerNode, format: file!.processingFormat);

    do {
        try audioEngine.start()
    } catch let error {
        print(error.localizedDescription)
        return
    }

    audioEngine.mainMixerNode.pan = 100 // No effect

    playerNode.scheduleFile(file!, at: nil){}

    DispatchQueue.global(qos: .background).async {
        print("audioEngine.isRunning = \(self.audioEngine.isRunning)");
        self.playerNode.play();
        print("playerNode.isPlaying = \(self.playerNode.isPlaying)");
    }
}

The file plays fine, but the pan value has no effect. I've tried different values (-1, 1, -100, +100) and for all of these the stereo playback remains in the middle.

What do I need to do to make panning work?

Upvotes: 1

Views: 796

Answers (2)

bberak
bberak

Reputation: 302

Try setting the "pan" property on the AVAudioSourceNode (using values -1 to 1) after calling the "start" function on AVAudioEngine. Setting the "pan" value before calling "start" had no affect for me.

let audioEngine = AVAudioEngine()
let sourceNode = AVAudioSourceNode { /* ... */ }
let mainMixer = audioEngine.mainMixerNode
let outputNode = audioEngine.outputNode
let format = outputNode.inputFormat(forBus: 0)
let inputFormat = AVAudioFormat(commonFormat: format.commonFormat,
                                        sampleRate: format.sampleRate,
                                        channels: 1,
                                        interleaved: format.isInterleaved)

audioEngine.attach(sourceNode)
audioEngine.connect(sourceNode, to: mainMixer, format: inputFormat)

do {
   try audioEngine.start()
} catch {
   print("Could not start engine: \(error.localizedDescription)")
}

sourceNode.pan = -1 // -1 to 1

Upvotes: 1

matt
matt

Reputation: 535306

I think the problem is that the main mixer node is not usable in that way. You should introduce another mixer node and set its pan, or set the pan directly on the AVAudioPlayerNode.

Upvotes: 2

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