Create/trim a video file using directshow

And here we go, for those who need to do something similar It's not that difficult as I thought in the beginning, when you know what you have to do! And that was exactly my main issue. I had no idea what to do or how to approach the task. So to get started in DirectShow you need to build a graph which do for you the task. I recommend to use GraphEdit provided with the SDK, or in my case GraphStudioNext. the best way to start is if you have any program that play's a video file or better an application that make a video file from a web cam. with the editor you can connect to that application and it will generate for you the graph used. Then you can create/simulate your own graph with your needs.

After that you only need to code your own graph. With the help of the documentations, the c++ code from the link provided by @RickZeeland in answer1 and your friend google, it's easy enough to know the basics.

and here is my code:

sing System;
using System.Collections.Generic;
using System.Runtime.InteropServices.ComTypes;
using System.Runtime.InteropServices;
using System.Threading;
using System.Windows.Forms;
using DirectShowLib;

namespace Modules.File.Video
{
   public class AviSplitter
   {
      private static void checkHR(int hr, string msg)
      {
         if (hr < 0)
         {
            LogFileManager.Instance.WriteToLogFile(msg, SwitchLevel.Info);
            DsError.ThrowExceptionForHR(hr);
         }
      }

      #region Member variables
      public static double Duration { get; private set; }
      public static long NrFramesInAVI { get; private set; }

      // graph builder interfaces
      private static ICaptureGraphBuilder2 pGraphBuilder;
      private static IMediaSeeking pmediaSeeking;
      #endregion

      private static void BuildGraph(IGraphBuilder pGraph, string FileName, string NewFile)
      {
         const bool USEDAVISPLITTER = false;
         int hr = 0;
         Guid guid = new Guid(USEDAVISPLITTER ? "D3588AB0-0781-11CE-B03A-0020AF0BA770"   // AVISource
                                               : "CEA8DEFF-0AF7-4DB9-9A38-FB3C3AEFC0DE"); // osAviSource

         //Graph builder
         pGraphBuilder = new CaptureGraphBuilder2() as ICaptureGraphBuilder2;
         hr = pGraphBuilder.SetFiltergraph(pGraph);
         checkHR(hr, "Can't SetFilterGraph");

         //Add AVI File Source
         IBaseFilter sourceFilter = (IBaseFilter)new AVIDec();
         //sourceFilter.SetSyncSource(null);   //Set Graph Clock to Null
         hr = pGraph.AddFilter(sourceFilter, "AVI File Source");
         checkHR(hr, "Can't add AVI File Source to Graph");
         //set Source filename        
         try
         {
            sourceFilter = DXHelper.CreateFilter(guid);
         }
         catch (System.IO.FileNotFoundException)
         {
            // can try to register and try again
         }
         if (null == sourceFilter) sourceFilter = RegisterAviSplitter(guid);
         if (null != sourceFilter)
         {
            DsError.ThrowExceptionForHR(pGraph.AddFilter(sourceFilter, "sourceFilter"));
            IFileSourceFilter sourceFilter_src = sourceFilter as IFileSourceFilter;
            if (sourceFilter_src == null) checkHR(unchecked((int)0x80004002), "Cant't get IFileSourceFilter");
            hr = sourceFilter_src.Load(FileName, null);
            checkHR(hr, "Can't load file");
         }

         //add AVI Mux
         IBaseFilter pAVIMux = (IBaseFilter)new AviDest();
         //pAVIMux.SetSyncSource(null);
         hr = pGraph.AddFilter(pAVIMux, "AVI MUX");
         checkHR(hr, "Can't add AVI Mux to graph");

         //connect AVI File Source and AVI Mux
         hr = pGraph.ConnectDirect(GetPin(sourceFilter, "Video 0"), GetPin(pAVIMux, "Input 01"), null);
         checkHR(hr, "Cant connect AVI File Source to AVI Mux");

         //add File writer
         IBaseFilter pFilewriter = (IBaseFilter)new FileWriter();
         //pFilewriter.SetSyncSource(null);
         hr = pGraph.AddFilter(pFilewriter, "File Writer");
         checkHR(hr, "Can't add File writer to graph");
         //Set destination filename
         IFileSinkFilter pFilewriter_sink = pFilewriter as IFileSinkFilter;
         if (pFilewriter_sink == null) checkHR(unchecked((int)0x8004002), "Can't get IFileSinkFilter");
         hr = pFilewriter_sink.SetFileName(NewFile, null);
         checkHR(hr, "Can't set filename");

         //connect AVI Mux and File writer         
         hr = pGraph.ConnectDirect(GetPin(pAVIMux, "AVI Out"), GetPin(pFilewriter, "in"), null);
         checkHR(hr, "Can't connect AVI Mux and File writer");
      }

      private static IBaseFilter RegisterAviSplitter(Guid guid)
      {
         string filePath = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location) + "\\registerOSAviSplitter.bat";
         System.Diagnostics.Process reg = new System.Diagnostics.Process();
         //This file registers .dll files as command components in the registry.
         reg.StartInfo.FileName = filePath;
         reg.StartInfo.UseShellExecute = false;
         reg.StartInfo.CreateNoWindow = true;
         reg.StartInfo.RedirectStandardOutput = true;
         reg.Start();
         reg.WaitForExit(10 * 1000);
         reg.Close();
         System.Threading.Thread.Sleep(2000);
         return DXHelper.CreateFilterSafe(guid);
      }

      private static IPin GetPin(IBaseFilter filter, string pinname)
      {
         IEnumPins epins;
         int hr = filter.EnumPins(out epins);
         checkHR(hr, "Can't ennumerate pins");
         IntPtr fetched = Marshal.AllocCoTaskMem(4);
         IPin[] pins = new IPin[1];
         while (epins.Next(1, pins, fetched) == 0)
         {
            PinInfo pinfo;
            pins[0].QueryPinInfo(out pinfo);
            bool found = (pinfo.name == pinname);
            DsUtils.FreePinInfo(pinfo);
            if (found) return pins[0];
         }
         checkHR(-1, "Pin not found");
         return null;
      }

      private static double TimeOfFrame(long frame)
      {
         double time = (double)frame * Duration;
         return time / (double)NrFramesInAVI;
      }

      private static double TimeOfMediaTime(long mediaTime)
      {
         return ((double)mediaTime / 10000000.0);
      }

      private static long MediaTimeOfTime(double time)
      {
         return (long)(time * 10000000.0);
      }

      private static double getDuration()
      {
         if (pmediaSeeking == null) return 0.1;
         long duration; pmediaSeeking.GetDuration(out duration);
         return TimeOfMediaTime(duration);
      }

      private static long GetNbOfFrames()
      {
         long ret = 0;
         if (pmediaSeeking != null)
         {
            try
            {
               long earliest, latest;
               pmediaSeeking.SetTimeFormat(TimeFormat.Frame);
               pmediaSeeking.GetAvailable(out earliest, out latest);
               pmediaSeeking.SetTimeFormat(TimeFormat.MediaTime);
               return latest;
            }
            catch { }
         }
         return ret;
      }

      public static void createNewFile(string fileName, string newFile, long startPos, long endPos)
      {
         try
         {
            IGraphBuilder graph = (IGraphBuilder)new FilterGraph();
            LogFileManager.Instance.WriteToLogFile("Building graph...", SwitchLevel.Info);

            BuildGraph(graph, fileName, "D:\\Test_Cut3.avi");
            LogFileManager.Instance.WriteToLogFile("Running...", SwitchLevel.Info);

            IMediaControl mediaControl = (IMediaControl)graph;
            IMediaEvent mediaEvent = (IMediaEvent)graph;


            pmediaSeeking = (IMediaSeeking)graph;
            NrFramesInAVI = GetNbOfFrames();
            Duration = getDuration();
            pmediaSeeking?.SetTimeFormat(TimeFormat.MediaTime);

            //Set Start Position
            long Starttime = MediaTimeOfTime(TimeOfFrame(startPos));
            LogFileManager.Instance.WriteToLogFile("Set Start at frame: " + startPos.ToString() + "[" + (Starttime / 10000000).ToString() + "])", SwitchLevel.Info);
            pmediaSeeking.SetPositions(Starttime, AMSeekingSeekingFlags.AbsolutePositioning, 0, AMSeekingSeekingFlags.NoPositioning);

            //set Stop Position
            long endtime = MediaTimeOfTime(TimeOfFrame(endPos));
            LogFileManager.Instance.WriteToLogFile("Set End at frame: " + endPos.ToString() + "[" + (Starttime / 10000000).ToString() + "])", SwitchLevel.Info);
            pmediaSeeking.SetPositions(endtime, AMSeekingSeekingFlags.NoPositioning, 0, AMSeekingSeekingFlags.AbsolutePositioning);

            int hr = mediaControl.Run();
            checkHR(hr, "Can't run the graph");

            bool stop = false;
            while (!stop)
            {
               Thread.Sleep(500);
               LogFileManager.Instance.WriteToLogFile(".", SwitchLevel.Info);
               EventCode ev;
               IntPtr p1, p2;
               Application.DoEvents();
               while (mediaEvent.GetEvent(out ev, out p1, out p2, 0) == 0)
               {
                  if (ev == EventCode.Complete || ev == EventCode.UserAbort)
                  {
                     mediaControl.StopWhenReady();
                     LogFileManager.Instance.WriteToLogFile("Done!", SwitchLevel.Info);
                     stop = true;
                  }
                  else if (ev == EventCode.ErrorAbort)
                  {
                     LogFileManager.Instance.WriteToLogFile(string.Format("An error occured: HRESULT={0,X}", p1), SwitchLevel.Info);
                     mediaControl.Stop();
                     stop = true;
                  }
                  mediaEvent.FreeEventParams(ev, p1, p2);
               }
            }
         }
         catch (COMException ex)
         {
            ErrorManager.Instance.HandleException(ex, SwitchLevel.Error);
            LogFileManager.Instance.WriteToLogFile("COM error: " + ex.ToString(), SwitchLevel.Info);
         }
         catch (Exception ex)
         {
            LogFileManager.Instance.WriteToLogFile("Error: " + ex.ToString(), SwitchLevel.Info);
            ErrorManager.Instance.HandleException(ex, SwitchLevel.Error);
         }
      }
   }
}