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DirectShow.NET

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4.94 (191 votes)
22 Jul 2002Public Domain
DirectShow for DVD and file playback, capture and sample grabber

Sample Image - directshownet.jpg

Disclaimer: Experimental code using DirectShow with the .NET Framework 1.0

Abstract

This experimental code shows how to use DirectShow with .NET and C#. This includes simple media playback, playing DVD discs, capturing video streams to disk and a sample picture grabber.

Note, this article doesn't save you from reading the detailed DirectShow SDK documentation! I will not explain DirectShow, only some of the used .NET Interop technologies!

DirectShow

DirectShow is a standardized Microsoft Win32 API to use any compliant movie or video device from your application. DirectShow is available with the current DirectX version 8.1(b) for Windows 98/ME/2000 and included in XP. Please install the latest version, this article doesn't support anything except 8.1 :

Again, I will not describe any DirectShow interfaces, you have to know them by installing the SDK for C++, reading the SDK documentation and understanding the SDK samples!

DirectShow is exposed as COM components and interfaces, at these two 'levels':

  • DirectShow custom interfaces - mainly for C++ programmers.
  • DirectShow VB components - designed for VB6, provides a type library.
You can use the DirectShow playback components for VB6 with .NET, as described in this CodeProject article: DirectShow MediaPlayer in C# (Daniel Strigl)

.NET Interop

While using the VB6 components with the provided type library is easy with .NET, there is no direct way to access the custom DirectShow interfaces. We have to use Interop with one of this approaches:

  • Use 'Managed Extensions for C++', as done e.g. by DirectX.NET
  • Rewrite all the interfaces from IDL to e.g. C# !
I chose the second strategy for this reasons :
  • Uses only one (managed) language (C#)
  • Most DirectShow interfaces are not very complex
  • DirectShow methods for simple playback/capturing are not time-critical
  • We can directly use the (documented) interfaces without limitations, no 'wrapper classes'
Sure, this has some drawbacks:
  • Much of initial work for rewriting the interfaces
  • You have to understand Interop to use it correctly
  • Not very .NET/OO-like
One typical rewrite of an IDL interface in C# looks like this :
// ======== IDL of ICaptureGraphBuilder2 (AXExtend.idl) ======
[
    object,
    uuid(93E5A4E0-2D50-11d2-ABFA-00A0C9C6E38D),
    pointer_default(unique)
]
interface ICaptureGraphBuilder2 : IUnknown {

    // Use this filtergraph
    HRESULT SetFiltergraph( [in] IGraphBuilder *pfg );

    // what filtergraph are you using?
    // *ppfg->Release() when you're done with it
    HRESULT GetFiltergraph( [out] IGraphBuilder **ppfg);
    ....
... using Interop attributes with C# will be translated to :
// ======== C# version of ICaptureGraphBuilder2 (DsExtend.cs) ======

   [ComVisible(true), ComImport,
    Guid("93E5A4E0-2D50-11d2-ABFA-00A0C9C6E38D"),
    InterfaceType( ComInterfaceType.InterfaceIsIUnknown )]
public interface ICaptureGraphBuilder2
{
        [PreserveSig]
   int SetFiltergraph( [In] IGraphBuilder pfg );

        [PreserveSig]
   int GetFiltergraph( [Out] out IGraphBuilder ppfg );
   ....

Once we have all this interface definitions in C#, we can start calling DirectShow just like we did in C++:

// ======== C++ code to create the COM instance of Filter Graph ========

    JIF(CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, 
                         IID_IGraphBuilder, (void **)&pGB));

    // Have the graph builder construct its the <BR>    // appropriate graph automatically
    JIF(pGB->RenderFile(wFile, NULL));

    // QueryInterface for DirectShow interfaces
    JIF(pGB->QueryInterface(IID_IMediaControl, (void **)&pMC));
    ....
... we replace CoCreateInstance with Activator.CreateInstance, and QueryInterface just is a simple cast in C#:
// ======== C# code to create the COM instance of Filter Graph ========

    Type comtype = null;
    object comobj = null;
    try {
        comtype = Type.GetTypeFromCLSID( Clsid.FilterGraph );
        if( comtype == null )
            throw new NotSupportedException( <BR>                "DirectX (8.1 or higher) not installed?" );
        comobj = Activator.CreateInstance( comtype );
        graphBuilder = (IGraphBuilder) comobj; comobj = null;
        
        int hr = graphBuilder.RenderFile( clipFile, null );
        if( hr < 0 )
            Marshal.ThrowExceptionForHR( hr );

        mediaCtrl    = (IMediaControl)  graphBuilder;
     ....

Projects Structure

The download contains all this C# source code:

\DirectShow\
     \DShowNET\              // the DirectShow interface definitions :
              \DsBugWO.cs      // workaround for a bug 
              \DsControl.cs    // ported from control.odl 
              \DsCore.cs       // ported from axcore.idl 
              \DsDevice.cs     // device enumerator, helper functions 
              \DsDVD.cs        // DVD interfaces from dvdif.idl 
              \DsExtend.cs     // ported from axextend.idl 
              \DsUtils.cs      // utility classes, SDK Common sources 
              \DsUuids.cs      // UUIDs and CLSIDs from uuids.h 
              \QEdit.cs        // grabber interfaces from qedit.idl 

     \CaptureNET\            // video stream capture sample 
     \DVDPlayerNET\          // DVD player sample 
     \PlayWndNET\            // simple media file playback 
     \SampleGrabberNET\      // picture grabber 

Playback

The first sample included in the download is PlayWndNET. It plays the known video and audio file formats of DirectShow like avi, mpg, wav, mid etc.

DirectShow playback

DVD Player

For the next sample, DVDPlayerNET you must have a third-party DVD codec installed, like WinDVD or PowerDVD. Then, the C# sample uses the DirectShow DVD interfaces to watch the movie. It also supports menu navigation.

DirectShow DVD

Grab Picture

The most complex sample provided is SampleGrabberNET. It shows a live video stream from a capture device like DV cam, web cam or TV card in a preview window. By pressing the 'Grab' toolbar-button, you can capture a still picture to a 24-Bit RGB bitmap file!

DirectShow picture grabber

The sample also supports the IAMTVTuner interface of a TV card, so you can switch the TV tuner channel.

Capturing

The last sample, CaptureNET can be used to capture a live video stream to disk. Note, the few settings can only be done once at startup, and writing to the AVI file starts immediately.

DirectShow Capturing

Limitations

  • EXPERIMENTAL! don't use it in production quality code.
  • The samples only provide partial and very basic functionality.
  • I did most tests on Windows XP and few on Windows ME.
  • Tested only on a very limited set of devices with only few media formats.
    I used a Logitech QuickCam, Sony DV camcorder, Hauppauge WinTV PCI and WinDVD.
  • Get the latest driver (WDM) from manufacturer.
  • Some devices fail if you select unsupported settings in the dialogs.
  • This code will NOT help to solve any DirectShow/WDM configuration problems.
  • Get >128MB RAM, >400MHz CPU, fast & huge harddisk.

License

This article, along with any associated source code and files, is licensed under A Public Domain dedication

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About the Author

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Comments and Discussions

 
AnswerRe: DirectShow TvTuner "cold start" Pin
Rolf Szomor9-Jul-09 9:17
memberRolf Szomor9-Jul-09 9:17 
AnswerRe: DirectShow TvTuner "cold start" Pin
RobstaHendricks16-Nov-09 5:23
memberRobstaHendricks16-Nov-09 5:23 
GeneralRe: DirectShow TvTuner "cold start" Pin
RobstaHendricks16-Nov-09 23:17
memberRobstaHendricks16-Nov-09 23:17 
GeneralRe: DirectShow TvTuner "cold start" Pin
SanShark18-Nov-09 21:36
memberSanShark18-Nov-09 21:36 
GeneralRe: DirectShow TvTuner "cold start" Pin
RobstaHendricks18-Nov-09 22:20
memberRobstaHendricks18-Nov-09 22:20 
QuestionICaptureGraphBuilder2::RenderStream method take lot off time to return Pin
Bhushan Badhe26-May-09 18:29
memberBhushan Badhe26-May-09 18:29 
GeneralBlack Images Pin
Jack987319-May-09 22:55
memberJack987319-May-09 22:55 
QuestionVideo from a Streaming server?? Pin
iFarhan29-Apr-09 20:08
memberiFarhan29-Apr-09 20:08 
Questionwhat to do after capturing pointer of data using DirectShow.NET Pin
Khurram Shakoor10-Apr-09 2:21
memberKhurram Shakoor10-Apr-09 2:21 
GeneralManage colors during Capturing Pin
anki12310-Mar-09 1:42
memberanki12310-Mar-09 1:42 
GeneralWatermark Videos Pin
anki1231-Mar-09 20:04
memberanki1231-Mar-09 20:04 
GeneralDshownet and x64 Pin
carle25725-Feb-09 19:37
membercarle25725-Feb-09 19:37 
QuestionCapturing Video and Image at the same time using DShowNet Pin
shankarsangoli26-Dec-08 9:07
membershankarsangoli26-Dec-08 9:07 
QuestionFlipping the subtitles in a Dvd Pin
GrizzlyDoug2-Dec-08 6:11
memberGrizzlyDoug2-Dec-08 6:11 
GeneralRecompressing files Pin
_malf28-Nov-08 2:39
member_malf28-Nov-08 2:39 
GeneralVC++ code Pin
islamicsoft8-Oct-08 1:32
memberislamicsoft8-Oct-08 1:32 
QuestionAudio... with CaptureNET Pin
deching5-Oct-08 12:47
memberdeching5-Oct-08 12:47 
QuestionRotation of Camera Pin
Yena papa22-Sep-08 2:04
memberYena papa22-Sep-08 2:04 
Questionhow to create source filter for rgb video frame datas. Pin
billqu_developer15-Sep-08 0:03
memberbillqu_developer15-Sep-08 0:03 
GeneralCodecs Pin
VCSKicks9-Sep-08 9:17
memberVCSKicks9-Sep-08 9:17 
GeneralProblem with mms-stream on second monitor Pin
PeterWalther9-Sep-08 9:13
memberPeterWalther9-Sep-08 9:13 
GeneralDoubleClick on VideoWindow in PlayWndNET-Project Pin
tabor2514-Aug-08 20:20
membertabor2514-Aug-08 20:20 
Generalvideo playing problem Pin
Member 469378711-Aug-08 21:25
memberMember 469378711-Aug-08 21:25 
Generalto capture image through web cam in web application and save in hard drive Pin
Member 27161587-Aug-08 23:52
memberMember 27161587-Aug-08 23:52 
GeneralCapture a Image from Video File Pin
ananduk764-Aug-08 7:58
memberananduk764-Aug-08 7:58 

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Article
Posted 21 Jul 2002

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