Video Capture in MonoTouch

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;

using MonoTouch.Foundation;
using MonoTouch.UIKit;
using System.Drawing;
using MonoTouch.CoreGraphics;
using MonoTouch.CoreAnimation;
using MonoTouch.AVFoundation;
using MonoTouch.CoreVideo;
using MonoTouch.CoreMedia;
using System.IO;
using System.Threading;
using MonoTouch.AssetsLibrary;

namespace VideoCapture
{
  public class VideoCapture : AVCaptureVideoDataOutputSampleBufferDelegate
	{
		public UIImageView ImageView { get; protected set; }

		public UILabel InfoLabel { get; protected set; }

		AVCaptureSession session;
		AVAssetWriter writer;
		AVAssetWriterInput inputWriter;
		CMTime lastSampleTime;
		NSUrl videoUrl;

		public VideoCapture (UIImageView imgView, UILabel label)
		{
			this.ImageView = imgView;
			this.InfoLabel = label;
		}

		public bool StartRecording ()
		{
			try {
				session = MaybeInitializeSession ();
				if (session == null) {
					Failure.Alert ("Couldn't initialize session");
					return false;
				}
				writer = MaybeInitializeAssetWriter ();
				if (writer == null) {
					Failure.Alert ("Couldn't initialize writer");
					return false;
				}
				inputWriter = MaybeInitializeInputWriter ();
				if (inputWriter == null) {
					Failure.Alert ("Couldn't initialize input writer");
					return false;
				}
				if (! writer.CanAddInput (inputWriter)) {
					Failure.Alert ("Couldn't add input writer to writer");
					return false;
				}
				writer.AddInput (inputWriter);

				session.StartRunning ();
				return true;
			} catch (Exception x) {
				Failure.Alert (x.Message);
				return false;
			}
		}

		public void StopRecording ()
		{
			try {
				session.StopRunning ();
				writer.FinishWriting(() => MoveFinishedMovieToAlbum());
			} catch (Exception x) {
				Failure.Alert (x.Message);
			}
		}

		//Protected
		protected AVCaptureSession MaybeInitializeSession ()
		{
			//Create the capture session
			var session = new AVCaptureSession () {
				SessionPreset = AVCaptureSession.PresetMedium
			};

			//Setup the video capture
			var captureDevice = AVCaptureDevice.DefaultDeviceWithMediaType (AVMediaType.Video);
			if (captureDevice == null) {
				Failure.Alert ("No captureDevice - this won't work on the simulator, try a physical device");
				return null;
			}
			var input = AVCaptureDeviceInput.FromDevice (captureDevice);
			if (input == null) {
				Failure.Alert ("No input - this won't work on the simulator, try a physical device");
				return null;
			}
			session.AddInput (input);
			
			// create a VideoDataOutput and add it to the sesion
			var output = new AVCaptureVideoDataOutput () {
				VideoSettings = new AVVideoSettings (CVPixelFormatType.CV32BGRA),
			};
			
			// configure the output
			var queue = new MonoTouch.CoreFoundation.DispatchQueue ("myQueue");
			output.SetSampleBufferDelegate (this, queue);
			session.AddOutput (output);

			return session;
		}

		protected AVAssetWriter MaybeInitializeAssetWriter ()
		{
			var filePath = Path.Combine (Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "Temporary.mov");
			if (File.Exists (filePath)) {
				File.Delete (filePath);
			}
			videoUrl = NSUrl.FromFilename (filePath);

			NSError error;
			var writer = new AVAssetWriter (videoUrl, AVFileType.QuickTimeMovie, out error);
			if (error != null) {
				Failure.Alert (error.LocalizedDescription);
				return null;
			}
			return writer;
		}

		protected AVAssetWriterInput MaybeInitializeInputWriter ()
		{
			try {
				var dictionary = NSDictionary.FromObjectsAndKeys (
				new NSObject[] { AVVideo.CodecH264, new NSNumber (640), new NSNumber (480)},
				new NSObject[] { AVVideo.CodecKey, AVVideo.WidthKey, AVVideo.HeightKey}
				);
			
				var writerInput = new AVAssetWriterInput (AVMediaType.Video, dictionary);
				writerInput.ExpectsMediaDataInRealTime = true;
				return writerInput;
			} catch (Exception x) {
				Failure.Alert (x.Message);
				return null;
			}
		}

		protected void MoveFinishedMovieToAlbum()
		{
			var lib = new ALAssetsLibrary();
			lib.WriteVideoToSavedPhotosAlbum(videoUrl, (o,s) => InfoLabel.BeginInvokeOnMainThread(() => InfoLabel.Text = "Movie saved to Album."));
		}

		//Implement AVCaptureVideoDataOutputSampleBufferDelegate
		int frame = 0;
		public override void DidOutputSampleBuffer (AVCaptureOutput captureOutput, CMSampleBuffer sampleBuffer, AVCaptureConnection connection)
		{
			try {
				lastSampleTime = sampleBuffer.PresentationTimeStamp;

				var image = ImageFromSampleBuffer (sampleBuffer);

				if(frame == 0)
				{
					writer.StartWriting();
					writer.StartSessionAtSourceTime(lastSampleTime);
					frame = 1;
				}
				String infoString = "";
				if(inputWriter.ReadyForMoreMediaData)
				{
					if(! inputWriter.AppendSampleBuffer(sampleBuffer))
					{
						infoString = "Failed to append sample buffer";
					}
					else
					{
						infoString = String.Format ("{0} frames captured", frame++);
					}
				}
				else
				{
					infoString = "Writer not ready";
				}

				ImageView.BeginInvokeOnMainThread (() => ImageView.Image = image);
				InfoLabel.BeginInvokeOnMainThread (() => InfoLabel.Text = infoString);
			} catch (Exception e) {
				Failure.Alert (e.Message);
			} finally {
				sampleBuffer.Dispose ();
			}
		}
		
		UIImage ImageFromSampleBuffer (CMSampleBuffer sampleBuffer)
		{
			// Get the CoreVideo image
			using (var pixelBuffer = sampleBuffer.GetImageBuffer () as CVPixelBuffer) {
				// Lock the base address
				pixelBuffer.Lock (0);
				// Get the number of bytes per row for the pixel buffer
				var baseAddress = pixelBuffer.BaseAddress;
				int bytesPerRow = pixelBuffer.BytesPerRow;
				int width = pixelBuffer.Width;
				int height = pixelBuffer.Height;
				var flags = CGBitmapFlags.PremultipliedFirst | CGBitmapFlags.ByteOrder32Little;
				// Create a CGImage on the RGB colorspace from the configured parameter above
				using (var cs = CGColorSpace.CreateDeviceRGB ())
				using (var context = new CGBitmapContext (baseAddress,width, height, 8, bytesPerRow, cs, (CGImageAlphaInfo) flags))
				using (var cgImage = context.ToImage ()) {
					pixelBuffer.Unlock (0);
					return UIImage.FromImage (cgImage);
				}
			}
		}
	}

	public class Failure
	{
		public static void Alert (string msg)
		{
			new NSString().InvokeOnMainThread( () => new UIAlertView("Trouble", msg, null, "OK", null).Show());
		}
	}

	public class ContentView : UIView
	{
		public UIImageView ImageView { get; protected set; }

		public UILabel InfoLabel { get; protected set; }

		public ContentView (UIColor fillColor, EventHandler recordToggle)
		{
			BackgroundColor = fillColor;

			ImageView = new UIImageView (new RectangleF (10, 10, UIScreen.MainScreen.Bounds.Width - 20, UIScreen.MainScreen.Bounds.Height - 120));
			ImageView.BackgroundColor = UIColor.Blue;

			InfoLabel = new UILabel (new RectangleF (UIScreen.MainScreen.Bounds.Width - 150, 10, 140, 50));

			var toggleButton = UIButton.FromType (UIButtonType.RoundedRect);
			toggleButton.SetTitle ("Record", UIControlState.Normal);
			toggleButton.Frame = new RectangleF (
				new PointF (UIScreen.MainScreen.Bounds.Width / 2 - toggleButton.IntrinsicContentSize.Width / 2, UIScreen.MainScreen.Bounds.Height - toggleButton.IntrinsicContentSize.Height - 50), toggleButton.IntrinsicContentSize);

			toggleButton.TouchUpInside += recordToggle;

			AddSubview (ImageView);
			AddSubview (InfoLabel);
			AddSubview (toggleButton);
		}
	}
	
	public class VideoCaptureController : UIViewController
	{
		String title;
		UIColor color;
		protected bool recording = false;
		protected VideoCapture videoCapture;

		public VideoCaptureController (UIColor viewColor, String title) : base ()
		{
			this.title = title;
			
			color = viewColor;
		}
		
		public override void DidReceiveMemoryWarning ()
		{
			// Releases the view if it doesn't have a superview.
			base.DidReceiveMemoryWarning ();
		}
		
		public override void ViewDidLoad ()
		{
			base.ViewDidLoad ();
			
			Title = title;
			
			var cv = new ContentView (color, RecordToggle);

			View = cv;
		}

		protected void RecordToggle (Object sender, EventArgs e)
		{
			if (! recording) {
				ContentView cv = View as ContentView;
				videoCapture = new VideoCapture (cv.ImageView, cv.InfoLabel);
				recording = videoCapture.StartRecording ();
			} else {
				videoCapture.StopRecording ();
				recording = false;
			}
			var newTitle = recording ? "Stop" : "Record";
			(sender as UIButton).SetTitle (newTitle, UIControlState.Normal);
		}
	}
	
	[Register ("AppDelegate")]
	public  class AppDelegate : UIApplicationDelegate
	{
		UIWindow window;
		
		public override bool FinishedLaunching (UIApplication app, NSDictionary options)
		{
			var viewController = new VideoCaptureController (UIColor.Red, "Main");

			window = new UIWindow (UIScreen.MainScreen.Bounds);
			window.RootViewController = viewController;
			
			window.MakeKeyAndVisible ();
			
			return true;
		}
		
	}
	
	public class Application
	{
		static void Main (string[] args)
		{
			UIApplication.Main (args, null, "AppDelegate");
		}
	}
}