WebRTC iOS: Record Remote Audio stream using WebRTC - ios

Question

I am working on an audio streaming application with recording functionality for a receiver.
I got stuck at the point where the user want to record audio stream on the receiver side.
Below is my code
Initialisation
var engine = AVAudioEngine()
var recordingFile: AVAudioFile?
var audioPlayer: AVAudioPlayer?
let player = AVAudioPlayerNode()
var isRecording: Bool = false
Initialise AudioEngine
func initializeAudioEngine() {
let input = self.engine.inputNode
let format = input.inputFormat(forBus: 0)
self.engine.attach(self.player)
let mainMixerNode = self.engine.mainMixerNode
self.engine.connect(input, to:mainMixerNode, format: format)
self.engine.prepare()
do {
try self.engine.start()
self.startRecording()
} catch (let error) {
print("START FAILED", error)
}
}
Start Recording
func startRecording() {
self.createRecordingFile()
self.engine.mainMixerNode.installTap(onBus: 0,
bufferSize: 1024,
format: self.engine.mainMixerNode.outputFormat(forBus: 0)) { (buffer, time) -> Void in
do {
self.isRecording = true
try self.recordingFile?.write(from: buffer)
} catch (let error) {
print("RECORD ERROR", error);
}
return
}
}
Create Buffer
private func createBuffer(forFileNamed fileName: String) -> AVAudioPCMBuffer? {
var res: AVAudioPCMBuffer?
if let fileURL = Bundle.main.url(forResource: fileName, withExtension: "caf") {
do {
let file = try AVAudioFile(forReading: fileURL)
res = AVAudioPCMBuffer(pcmFormat: file.processingFormat, frameCapacity:AVAudioFrameCount(file.length))
if let _ = res {
do {
try file.read(into: res!)
} catch (let error) {
print("ERROR read file", error)
}
}
} catch (let error) {
print("ERROR file creation", error)
}
}
return res
}
Stop Recording
func stopRecording() {
self.engine.mainMixerNode.removeTap(onBus: 0)
}
I am trying to record using earphone, but It's not working

Answer 1

Its will work because once you setup
let audiosession = AVAudioSession()
As AVAudioSessionCategoryPlayAndRecord and set
audiosession.setActive(true)
It will start recording whichever audio dump to device.

Answer 2

WebRTC does not have any Internal API to start or stop recording.
We can try using AVAudioSession instead.
First setUp Audio session
func setUPAudioSession() -> Bool {
let audiosession = AVAudioSession()
do {
try audiosession.setCategory(AVAudioSessionCategoryPlayAndRecord)
} catch(let error) {
print("--> \(error.localizedDescription)")
}
do {
try audiosession.setActive(true)
} catch (let error) {
print("--> \(error.localizedDescription)")
}
return audiosession.isInputAvailable;
}
After setUp the audio session now start recording as below
func startRecording() -> Bool {
var settings: [String: Any] = [String: String]()
settings[AVFormatIDKey] = kAudioFormatLinearPCM
settings[AVSampleRateKey] = 8000.0
settings[AVNumberOfChannelsKey] = 1
settings[AVLinearPCMBitDepthKey] = 16
settings[AVLinearPCMIsBigEndianKey] = false
settings[AVLinearPCMIsFloatKey] = false
settings[AVAudioQualityMax] = AVEncoderAudioQualityKey
//Create device directory where recorded file will be save automatically
let searchPaths: [String] = NSSearchPathForDirectoriesInDomains(.documentDirectory, .allDomainsMask, true)
let documentPath_ = searchPaths.first
let pathToSave = "\(documentPath_)/\(dateString)"
let url: URL = URL(pathToSave)
recorder = try? AVAudioRecorder(url: url, settings: settings)
// Initialize degate, metering, etc.
recorder.delegate = self;
recorder.meteringEnabled = true;
recorder?.prepareToRecord()
if let recordIs = recorder {
return recordIs.record()
}
return false
}
Play recorded file
func playrecodingFile() {
//Get the path of recorded file saved in previous method
let searchPaths: [String] = NSSearchPathForDirectoriesInDomains(.documentDirectory, .allDomainsMask, true)
let documentPath_ = searchPaths.first
let fileManager = FileManager.default
let arrayListOfRecordSound: [String]
if fileManager.fileExists(atPath: recordingFolder()) {
let arrayListOfRecordSound = try? fileManager.contentsOfDirectory(atPath: documentPath_)
}
let selectedSound = "\(documentPath_)/\(arrayListOfRecordSound.first)"
let url = URL.init(fileURLWithPath: selectedSound)
let player = try? AVAudioPlayer(contentsOf: url)
player?.delegate = self;
try? AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
player?.prepareToPlay()
player?.play()
}
Stop recording
func stopRecording() {
recorder?.stop()
}
pauseRecording
func pauseRecording() {
recorder?.pause()
}
Stop recording
func stopRecording() {
recorder?.stop()
}