Kiefer Hagin Kiefer Hagin - 1 month ago 11
iOS Question

Play system sound while recording video/audio

I'm trying to play a "beep" sound as required by apple when I start recording a video. I've found through SO and other sources that you can't play a sound while you have an audio input going without some configuration.

Here's my attempt at the configuration method:

private void SetupAudio()
{
beepSound = AssetBank.GetSystemSoundWav("video_record", "video_beep");
AudioSession.Initialize();
AudioSession.Interrupted += delegate
{
Console.WriteLine("Interrupted handler");
};

AudioSession.Category = AudioSessionCategory.PlayAndRecord;
AudioSession.OverrideCategoryMixWithOthers = true;

NSError err;
AVAudioSession.SharedInstance().SetActive(true, out err);
}


And here's my code where I setup the recording session:

public void SetupVideoCaptureSession(AVCaptureDevicePosition position)
{

// Setup devices
foreach (var device in AVCaptureDevice.Devices)
{
if (device.HasMediaType(AVMediaType.Video))
{
if (device.Position == AVCaptureDevicePosition.Front)
{
frontCam = device;
} else if (device.Position == AVCaptureDevicePosition.Back)
{
backCam = device;
}
}
}

// Create capture session
captureSession = new AVCaptureSession();
captureSession.BeginConfiguration();
captureSession.SessionPreset = AVCaptureSession.Preset640x480;
// Create capture device

switch (position)
{
case AVCaptureDevicePosition.Back:
videoDevice = backCam;
break;

case AVCaptureDevicePosition.Front:
videoDevice = frontCam;
break;
}

if (null == videoDevice)
{
using (var alert = new UIAlertView { Message = "No camera detected!" })
{
alert.AddButton("Okay!");
alert.Show();
}
return;
}

audioDevice = AVCaptureDevice.DefaultDeviceWithMediaType(AVMediaType.Audio);

// Create capture device input
NSError videoError, audioError;
videoDeviceInput = new AVCaptureDeviceInput(videoDevice, out videoError);
audioDeviceInput = new AVCaptureDeviceInput(audioDevice, out audioError);

captureSession.AddInput(videoDeviceInput);
captureSession.AddInput(audioDeviceInput);

// Create capture device output
videoOutput = new AVCaptureMovieFileOutput();
videoOutput.MaxRecordedDuration = new CMTime(10, 1);

captureSession.AddOutput(videoOutput);

if (null != previewLayer)
previewLayer.RemoveFromSuperLayer();

// Create preview layer
previewLayer = AVCaptureVideoPreviewLayer.FromSession(captureSession);
previewLayer.Orientation = AVCaptureVideoOrientation.Portrait;
previewLayer.VideoGravity = "AVLayerVideoGravityResizeAspectFill";
previewLayer.Frame = new RectangleF(new PointF(), ScreenSize);

this.ParentScrollView.Layer.InsertSublayer(previewLayer, 0);

// Start capture session

SetupAudio();
captureSession.CommitConfiguration();
captureSession.StartRunning();
}


No matter what I try, I can't get a sound to play after I've started the capture session. Anyone solved this in MonoTouch?

Answer

This is what I use in The Harlem Shake:

AudioSession.Initialize();
AudioSession.Category = AudioSessionCategory.MediaPlayback;
AudioSession.OverrideCategoryMixWithOthers = true;

Then to turn it off, I do this:

AudioSession.Initialize();
AudioSession.Category = AudioSessionCategory.AmbientSound;
AudioSession.OverrideCategoryMixWithOthers = false;

This allows me to play "the Harlem Shake" with AVAudioPlayer during video capture. It also overrides the silent switch on the iDevice. I don't know if AudioSession.Initialize() is required on both parts, you might play around with just calling it once.

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