KBB KBB - 6 days ago 5
iOS Question

Saving Audio After Effect in iOS

i am developing an applicatoin so that people can record and change their voices thru app and share it . Basically i so many things and now its time to ask you to help . Here is my play function which plays recorded audio file and adds effects on it .

private func playAudio(pitch : Float, rate: Float, reverb: Float, echo: Float) {
// Initialize variables
audioEngine = AVAudioEngine()
audioPlayerNode = AVAudioPlayerNode()
audioEngine.attachNode(audioPlayerNode)

// Setting the pitch
let pitchEffect = AVAudioUnitTimePitch()
pitchEffect.pitch = pitch
audioEngine.attachNode(pitchEffect)

// Setting the platback-rate
let playbackRateEffect = AVAudioUnitVarispeed()
playbackRateEffect.rate = rate
audioEngine.attachNode(playbackRateEffect)

// Setting the reverb effect
let reverbEffect = AVAudioUnitReverb()
reverbEffect.loadFactoryPreset(AVAudioUnitReverbPreset.Cathedral)
reverbEffect.wetDryMix = reverb
audioEngine.attachNode(reverbEffect)

// Setting the echo effect on a specific interval
let echoEffect = AVAudioUnitDelay()
echoEffect.delayTime = NSTimeInterval(echo)
audioEngine.attachNode(echoEffect)

// Chain all these up, ending with the output
audioEngine.connect(audioPlayerNode, to: playbackRateEffect, format: nil)
audioEngine.connect(playbackRateEffect, to: pitchEffect, format: nil)
audioEngine.connect(pitchEffect, to: reverbEffect, format: nil)
audioEngine.connect(reverbEffect, to: echoEffect, format: nil)
audioEngine.connect(echoEffect, to: audioEngine.outputNode, format: nil)

audioPlayerNode.stop()

let length = 4000
let buffer = AVAudioPCMBuffer(PCMFormat: audioPlayerNode.outputFormatForBus(0),frameCapacity:AVAudioFrameCount(length))
buffer.frameLength = AVAudioFrameCount(length)

try! audioEngine.start()


let dirPaths: AnyObject = NSSearchPathForDirectoriesInDomains( NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)[0]
let tmpFileUrl: NSURL = NSURL.fileURLWithPath(dirPaths.stringByAppendingPathComponent("effectedSound.m4a"))


do{
print(dirPaths)
let settings = [AVFormatIDKey: NSNumber(unsignedInt: kAudioFormatMPEG4AAC), AVSampleRateKey: NSNumber(integer: 44100), AVNumberOfChannelsKey: NSNumber(integer: 2)]
self.newAudio = try AVAudioFile(forWriting: tmpFileUrl, settings: settings)

audioEngine.outputNode.installTapOnBus(0, bufferSize: (AVAudioFrameCount(self.player!.duration)), format: self.audioPlayerNode.outputFormatForBus(0)){
(buffer: AVAudioPCMBuffer!, time: AVAudioTime!) in

print(self.newAudio.length)
print("=====================")
print(self.audioFile.length)
print("**************************")
if (self.newAudio.length) < (self.audioFile.length){

do{
//print(buffer)
try self.newAudio.writeFromBuffer(buffer)
}catch _{
print("Problem Writing Buffer")
}
}else{
self.audioPlayerNode.removeTapOnBus(0)
}

}
}catch _{
print("Problem")
}

audioPlayerNode.play()

}


I guess the problem is i am installTapOnBus to audioPlayerNode but the effected audio is on audioEngine.outputNode .However i tried to installTapOnBus to audioEngine.outputNode but it gives me error.Also i've tried to connect effects to audioEngine.mixerNode but it also not a solution . So that do you have any experiences on saving effected audio file ? How can i get this effected audio?

Any help is appreciated

Thank you

KBB KBB
Answer

Here it is my solution to question :

func playAndRecord(pitch : Float, rate: Float, reverb: Float, echo: Float) {
    // Initialize variables

// These are global variables . if you want you can just  (let audioEngine = etc ..) init here these variables
    audioEngine = AVAudioEngine()
    audioPlayerNode = AVAudioPlayerNode()
    audioEngine.attachNode(audioPlayerNode)
    playerB = AVAudioPlayerNode()

    audioEngine.attachNode(playerB)

    // Setting the pitch
    let pitchEffect = AVAudioUnitTimePitch()
    pitchEffect.pitch = pitch
    audioEngine.attachNode(pitchEffect)

    // Setting the platback-rate
    let playbackRateEffect = AVAudioUnitVarispeed()
    playbackRateEffect.rate = rate
    audioEngine.attachNode(playbackRateEffect)

    // Setting the reverb effect
    let reverbEffect = AVAudioUnitReverb()
    reverbEffect.loadFactoryPreset(AVAudioUnitReverbPreset.Cathedral)
    reverbEffect.wetDryMix = reverb
    audioEngine.attachNode(reverbEffect)

    // Setting the echo effect on a specific interval
    let echoEffect = AVAudioUnitDelay()
    echoEffect.delayTime = NSTimeInterval(echo)
    audioEngine.attachNode(echoEffect)

    // Chain all these up, ending with the output
    audioEngine.connect(audioPlayerNode, to: playbackRateEffect, format: nil)
    audioEngine.connect(playbackRateEffect, to: pitchEffect, format: nil)
    audioEngine.connect(pitchEffect, to: reverbEffect, format: nil)
    audioEngine.connect(reverbEffect, to: echoEffect, format: nil)
    audioEngine.connect(echoEffect, to: audioEngine.mainMixerNode, format: nil)


    // Good practice to stop before starting
    audioPlayerNode.stop()

    // Play the audio file 
// this player is also a global variable  AvAudioPlayer
    if(player != nil){
    player?.stop()
    }

    // audioFile here is our original audio
    audioPlayerNode.scheduleFile(audioFile, atTime: nil, completionHandler: {
        print("Complete")
    })


    try! audioEngine.start()


    let dirPaths: AnyObject = NSSearchPathForDirectoriesInDomains( NSSearchPathDirectory.DocumentDirectory,  NSSearchPathDomainMask.UserDomainMask, true)[0]
    let tmpFileUrl: NSURL = NSURL.fileURLWithPath(dirPaths.stringByAppendingPathComponent("effectedSound2.m4a"))

//Save the tmpFileUrl into global varibale to not lose it (not important if you want to do something else)
filteredOutputURL = tmpFileUrl

    do{
        print(dirPaths)

        self.newAudio = try! AVAudioFile(forWriting: tmpFileUrl, settings:  [
            AVFormatIDKey: NSNumber(unsignedInt:kAudioFormatAppleLossless),
            AVEncoderAudioQualityKey : AVAudioQuality.Low.rawValue,
            AVEncoderBitRateKey : 320000,
            AVNumberOfChannelsKey: 2,
            AVSampleRateKey : 44100.0
            ])

        let length = self.audioFile.length


        audioEngine.mainMixerNode.installTapOnBus(0, bufferSize: 1024, format: self.audioEngine.mainMixerNode.inputFormatForBus(0)) {
            (buffer: AVAudioPCMBuffer!, time: AVAudioTime!) -> Void in


            print(self.newAudio.length)
            print("=====================")
            print(length)
            print("**************************")

            if (self.newAudio.length) < length {//Let us know when to stop saving the file, otherwise saving infinitely

                do{
                    //print(buffer)
                    try self.newAudio.writeFromBuffer(buffer)
                }catch _{
                    print("Problem Writing Buffer")
                }
            }else{
                self.audioEngine.mainMixerNode.removeTapOnBus(0)//if we dont remove it, will keep on tapping infinitely

                //DO WHAT YOU WANT TO DO HERE WITH EFFECTED AUDIO

             }

        }
    }catch _{
        print("Problem")
    }

    audioPlayerNode.play()

}
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