VideoRenderer.cs

// 
// This is the source code of Telegram for Windows Phone v. 3.x.x.
// It is licensed under GNU GPL v. 2 or later.
// You should have received a copy of the license in this archive (see LICENSE).
// 
// Copyright Evgeny Nadymov, 2013-present.
// 
using Microsoft.Phone.Media;
using PhoneVoIPApp.BackEnd;
using System;
using System.Diagnostics;
using System.Windows;

namespace PhoneVoIPApp.Agents
{
    /// <summary>
    /// A class that renders video from the background process.
    /// Note, the MediaElement that actually displays the video is in the UI process - 
    /// this class receives video from the remote party and writes it to a media streamer.
    /// The media streamer handles connecting the rendered video stream to the media element that
    /// displays it in the UI process.
    /// </summary>
    internal class VideoRenderer : IVideoRenderer
    {
        /// <summary>
        /// Constructor
        /// </summary>
        internal VideoRenderer()
        {
        }

        #region IVideoRenderer methods

        /// <summary>
        /// Start rendering video.
        /// Note, this method may be called multiple times in a row.
        /// </summary>
        public void Start()
        {
            if (this.isRendering)
                return; // Nothing more to be done

            Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                try
                {
                    Debug.WriteLine("[VideoRenderer::Start] Video rendering setup");
                    StartMediaStreamer();
                    this.isRendering = true;
                }
                catch (Exception err)
                {
                    Debug.WriteLine("[VideoRenderer::Start] " + err.Message);
                }
            });
        }

        private void StartMediaStreamer()
        {
            if (mediaStreamer == null)
            {
                mediaStreamer = MediaStreamerFactory.CreateMediaStreamer(123);
            }

            // Using default resolution of 640x480
            mediaStreamSource = new VideoMediaStreamSource(null, 640, 480);
            mediaStreamer.SetSource(mediaStreamSource);
        }

        /// <summary>
        /// Stop rendering video.
        /// Note, this method may be called multiple times in a row.
        /// </summary>
        public void Stop()
        {
            Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                if (!this.isRendering)
                    return; // Nothing more to be done

                Debug.WriteLine("[VoIP Background Process] Video rendering stopped.");
                mediaStreamSource.Shutdown();                
                mediaStreamSource.Dispose();
                mediaStreamSource = null;
                mediaStreamer.Dispose();
                mediaStreamer = null;

                this.isRendering = false;
            });
        }

        #endregion

        #region Private members

        // Indicates if rendering is already in progress or not
        private bool isRendering;
        private VideoMediaStreamSource mediaStreamSource;
        private MediaStreamer mediaStreamer;

        #endregion
    }
}