Remotely/Server/Services/RemoteControlSessionRecorder.cs

using Microsoft.AspNetCore.Hosting;
using Remotely.Server.Data;
using Remotely.Server.Models;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Threading.Tasks;

namespace Remotely.Server.Services
{
    public class RemoteControlSessionRecorder
    {
        private static bool IsProcessing { get; set; }
        private static ConcurrentQueue<RemoteControlFrame> FrameQueue { get; } = new ConcurrentQueue<RemoteControlFrame>();
        private static ConcurrentDictionary<string, RecordingSessionState> SessionStates { get; } = new ConcurrentDictionary<string, RecordingSessionState>();
        private static object LockObject { get; } = new object();

        private IWebHostEnvironment HostingEnv { get; }
        private DataService DataService { get; }

        public RemoteControlSessionRecorder(IWebHostEnvironment hostingEnv, DataService dataService)
        {
            HostingEnv = hostingEnv;
            DataService = dataService;
        }
        internal void SaveFrame(byte[] frameBytes, int left, int top, int width, int height, string viewerID, string machineName, DateTime startTime)
        {
            var rcFrame = new RemoteControlFrame(frameBytes, left, top, width, height, viewerID, machineName, startTime);
            FrameQueue.Enqueue(rcFrame);

            lock (LockObject)
            {
                if (!IsProcessing)
                {
                    IsProcessing = true;
                    Task.Run(new Action(StartProcessing));
                }
            }
        }

        internal void StartProcessing()
        {
            lock (LockObject)
            {
                try
                {
                    while (FrameQueue.Count > 0)
                    {
                        if (FrameQueue.TryDequeue(out var frame))
                        {
                            var saveDir = Directory.CreateDirectory(GetSaveFolder(frame));

                            var saveFile = Path.Combine(saveDir.FullName, $"Recording.mp4");

                            if (!SessionStates.ContainsKey(frame.ViewerID))
                            {
                                SessionStates[frame.ViewerID] = new RecordingSessionState()
                                {
                                    CumulativeFrame = new Bitmap(frame.Width, frame.Height)
                                };
                                var ffmpegProc = new Process();
                                SessionStates[frame.ViewerID].FfmpegProcess = ffmpegProc;

                                ffmpegProc.StartInfo.FileName = "ffmpeg.exe";
                                ffmpegProc.StartInfo.Arguments = $"-y -f image2pipe -i pipe:.jpg -r 5 \"{saveFile}\"";
                                ffmpegProc.StartInfo.UseShellExecute = false;
                                ffmpegProc.StartInfo.RedirectStandardInput = true;

                                ffmpegProc.Start();
                            }

                            var bitmap = SessionStates[frame.ViewerID].CumulativeFrame;
                            using (var graphics = Graphics.FromImage(bitmap))
                            {
                                using (var ms = new MemoryStream(frame.FrameBytes))
                                {
                                    using (var saveImage = Image.FromStream(ms))
                                    {
                                        graphics.DrawImage(saveImage, frame.Left, frame.Top);
                                    }
                                }
                            }
                            bitmap.Save(SessionStates[frame.ViewerID].FfmpegProcess.StandardInput.BaseStream, ImageFormat.Jpeg);
                        }
                    }
                }
                catch (Exception ex)
                {
                    DataService.WriteEvent(ex);
                }
                finally
                {
                    IsProcessing = false;
                }
            }
        }

        private string GetSaveFolder(RemoteControlFrame frame)
        {
            return Path.Combine(
                        HostingEnv.ContentRootPath,
                        "Recordings",
                        frame.StartTime.Year.ToString().PadLeft(4, '0'),
                        frame.StartTime.Month.ToString().PadLeft(2, '0'),
                        frame.StartTime.Day.ToString().PadLeft(2, '0'),
                        frame.MachineName,
                        frame.ViewerID,
                        frame.StartTime.ToString("HH.mm.ss.fff"));
        }

        internal void StopProcessing(string viewerID)
        {
            SessionStates[viewerID].FfmpegProcess.StandardInput.Flush();
            SessionStates[viewerID].FfmpegProcess.StandardInput.Close();
            SessionStates[viewerID].FfmpegProcess.Close();
            SessionStates.TryRemove(viewerID, out _);
        }
    }
}