Audio Functionality

audioRecordingFunctionality.swift

// MARK:  AUDIO FUNCTIONALITY
    var captureSession: AVCaptureSession?
    var micInput:AVCaptureDeviceInput?
    var audioOutput:AVCaptureAudioDataOutput?
    
    
    func startAudioRecording(completionHandler:@escaping(Bool) -> ()) {
        
        let microphone = AVCaptureDevice.default(.builtInMicrophone, for: AVMediaType.audio, position: .unspecified)
        
        do {
            try self.micInput = AVCaptureDeviceInput(device: microphone!);
            
            self.captureSession = AVCaptureSession();
            
            if (self.captureSession?.canAddInput(self.micInput!))! {
                self.captureSession?.addInput(self.micInput!);
                
                self.audioOutput = AVCaptureAudioDataOutput();
                
                if self.captureSession!.canAddOutput(self.audioOutput!){
                    self.captureSession!.addOutput(self.audioOutput!)
                    self.audioOutput?.setSampleBufferDelegate(self, queue: DispatchQueue.global());
                    
                    self.captureSession?.startRunning();
                    completionHandler(true);
                }
                
            }
        }
        catch {
            completionHandler(false);
        }
    }
    
    func endAudioRecording() { //completionHandler:@escaping()->()

        self.captureSession!.stopRunning();
    }
    
    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
        
        
        // You now have the sample buffer - correct the timestamp to the video timestamp
        
        //https://github.com/takecian/video-examples-ios/blob/master/recordings/TimelapseCameraEngine.swift
        
        var count: CMItemCount = 0
        CMSampleBufferGetSampleTimingInfoArray(sampleBuffer, entryCount: 0, arrayToFill: nil, entriesNeededOut: &count);
        var info = [CMSampleTimingInfo](repeating: CMSampleTimingInfo(duration: CMTimeMake(value: 0, timescale: 0), presentationTimeStamp: CMTimeMake(value: 0, timescale: 0), decodeTimeStamp: CMTimeMake(value: 0, timescale: 0)), count: count)
        CMSampleBufferGetSampleTimingInfoArray(sampleBuffer, entryCount: count, arrayToFill: &info, entriesNeededOut: &count);
        
        let scale = CMTimeScale(NSEC_PER_SEC)
        var currentFrameTime:CMTime = CMTime(value: CMTimeValue((self.sceneView.session.currentFrame!.timestamp) * Double(scale)), timescale: scale);
        
        currentFrameTime = currentFrameTime-self.videoStartTime!;
        
        for i in 0..<count {
            info[i].decodeTimeStamp = currentFrameTime
            info[i].presentationTimeStamp = currentFrameTime
        }

        var soundbuffer:CMSampleBuffer?
        
        CMSampleBufferCreateCopyWithNewTiming(allocator: kCFAllocatorDefault, sampleBuffer: sampleBuffer, sampleTimingEntryCount: count, sampleTimingArray: &info, sampleBufferOut: &soundbuffer);
        

        self.audioInput?.append(soundbuffer!);
    }