DirectShow.NET

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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 :

• DirectX download

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!

• DirectX SDK on MSDN
• DirectShow documentation on MSDN

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 
    // 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( 
                "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.

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.

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!

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.

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.

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VC++ code islamicsoft 2:32 8 Oct '08   hye sir, I want to code in VC++ kindly help me Sign In·View Thread·PermaLink Audio... with CaptureNET deching 13:47 5 Oct '08   do I make reference to the project C# CaptureNET, is possible to integrate the audio with the video CAM? if YES..how can I do? thanks Nicola - brunelli@gmail.com Sign In·View Thread·PermaLink 1.67/5 (2 votes) Rotation of Camera Yena papa 3:04 22 Sep '08   Hello, is it possible to rotate the WebCam Stream? Im' working with some couple of Cameras and they are fixed on a frame. To control multi Cameras at the same time was successful, but some of them have vertically fixed on the frame, so I just see the motion pictures which turned to 90 grad to left(or right). Thanks. Sign In·View Thread·PermaLink how to create source filter for rgb video frame datas. billqu_developer 1:03 15 Sep '08   I can get rgb video frame datas from other program api, I need to add them into a .wmv file. How should I do? Sign In·View Thread·PermaLink Codecs VCKicks 10:17 9 Sep '08   First off, great article. I was playing around with the code and saving avi's to different codecs would be a nice addition. Awesome job Visit Visual C# Kicks for more free C#.Net articles, resources, and downloads at http://vckicks.110mb.com Sign In·View Thread·PermaLink Problem with mms-stream on second monitor PeterWalther 10:13 9 Sep '08   Hi, i've build a player which play some playlists. These playlists contain some images via des-timeline and a mms-stream. Now i start the player in monitor 1. All is perfect. Then i move the player in monitor 2. The des-timeline (with the images) is no problem, but when the stream should start, i can hear for half a second it is connecting and then breaks down. What is the problem?? Sign In·View Thread·PermaLink 1.00/5 (1 vote) Can it save video to compressed format avigodse 22:55 4 Sep '08   As I have seen this application, it saves stream as .avi file, and it holds lot of disc space for very little time of recording. Is it possible to save it in lesser or in compressed video format. Thanks in Advance Avinash S. Godse Sign In·View Thread·PermaLink DoubleClick on VideoWindow in PlayWndNET-Project tabor25 21:20 14 Aug '08   Hello, playing around with the PlayWndNET-Project, i want to switch to fullscreen mode by a doubleclick with the mouse instead of pressing the "F"- or "Enter"-Key. Like MSDN says i tried videoWin.put_MessageDrain(this.Handle) after setting the video window owner with videoWin.put_Owner(this.Handle) in the PlayClip()-method but without success. Anymore i'am not able to catch mouse events. Has someone an idea how to solve this problem? Best regards Tabor25 Sign In·View Thread·PermaLink video playing problem Member 4693787 22:25 11 Aug '08   I have written an application to display video. When running in a dual monitor system the video become black in one and available in other. I tested medial player , it also have the same problem ,but when i disabled the video overlay of media player .i was able to see the video in dual monitors. Can any body pls send me ideas about this. Thanks in advance Sign In·View Thread·PermaLink to capture image through web cam in web application and save in hard drive Member 2716158 0:52 8 Aug '08   i have a requirement where we need to capture images through web cam. i have to capture the image on clicking a button in a web browser and display in the web page. please suggest me a solution with sample code in C#. we are using asp.net framework 1.1 with C#. Sign In·View Thread·PermaLink 1.50/5 (2 votes) Capture a Image from Video File ananduk76 8:58 4 Aug '08   I have seen your code, it was so good. I have a question, Is there way to capture a image from Video File? I have few files that will play on windows media Control (WMPLib) in C#, i want to capture a image from that file. Can you please let me know how to do that Thanks Vijay Sign In·View Thread·PermaLink 1.00/5 (2 votes) How to find out Video Bit rate of SourceFile using directshow/Windows media interfaces shilpadhamal 3:35 26 Jul '08   I am working on one project which transcodes file.Transcoding is working fine. But I need to find out BitRate of Video stream of INPUT file. I am able to find out Audio/Video Bitrate of OUTPUT file using DirectShow IMediaDet interface. The coding snippets are as follows, bool MediaInfo(Filename) { IMediaDet *obj; ... ... obj.put_Filename(Filename); obj.get_OutputStreams(pVal); for(index=0;index<pval;index++> { obj.put_CurrentStream(index); obj.get_StreamType(guid); //here checking whether current stream is VIDEO stream //collecting information in VIDEOINFOHEADER structure //here checking whether current stream is AUDIO stream //collecting information in VIDEOINFOHEADER structure } } Here I am getting all the info. of output file/destination file after build graph is render. pBuildGraph->RenderFile(InputFileName); pMediaControl->Run(); MediaInfo(Filename); but when I call the same function i.e.MediaInfo(Filename) *before* building the graph, just to fetch all info of input file/source file, it gives me all info like Audio bit rate,lengthofStream,DurationOfstremIn bytes etc. but VideoBitRate is coming as 0 (ZERO). Please help me out to find out this info. Thanks in advance for your co-operation. Sign In·View Thread·PermaLink Video FrameSize doesn't getting effective on capturing the frame lokesh_17 4:26 10 Jul '08   By default the framesize is 320x240 on setting the frame size to 640x480, and capturing the frame for that size is not effective rather its capturing at 320x240 frame size. Sign In·View Thread·PermaLink 2.00/5 (1 vote) How to render Digital video file(.dv) using directshow san076 20:32 17 Jun '08   Hi all, IM using Directx9. I use this "DirectshowSouce" code to render all type of file. I can able to play(avi, mpg, mpeg, mov, wmv & asf ) files using directshow. But Im able to render Digital video(.dv ) file. please help me to play the digital video file using directshow. I have install Dv Codec but still dv file is not played. Thanks in Advance. Sign In·View Thread·PermaLink Compact framework Abhishek Ramesh Keshav 12:41 17 Jun '08   I am working on WM6 and this library looks very promising. So please let me know the answer to this question. Will this library work on compact framework? If not, what are the steps to be taken to port it to compact framework? Sign In·View Thread·PermaLink 1.00/5 (2 votes) Play big files jjdelgado 7:25 17 Jun '08   Hi, I'm trying to create an application based in DShowNet. It's work well but I'm stuck at a problem. I can't play a big video, in this case the size of video is about 1:31:00 and 700Mb of size. I'm programing in C# and tests some examples that I see here but none of them helped. Can anyone help me in this solution? Someone have any idea how can I solve this problem? Thank you for your help, João Delgado, Sign In·View Thread·PermaLink 2.00/5 (1 vote) how to configure output sampling rate and number of channels?? wzefzaf 3:21 15 Jun '08   hello, I'm having troubles configuring the ouput format and properties (sampling rate and nbr of channels) in the graph!! I'm using DirectShowNET with C# and trying to convert a wave (or MP3) file to a CCITT ALAW 8KH mono.. I really thought that I did the hard part when I converted my wave file to CCITT ALaw...but the problem is that the output file is 44Khz stereo..and I can't change it..even, when the input file is PCM MONO 8KH 8Bit...the output is still stereo 44Khz (it change in the within graph)..I tried to act on the output PIN of ACM Wrapper..but no success.. this my graph with Graphedit plus: FILE SOURCE(Async)-->WAVE PARSER-->ACM Wrapper-->CCITT A-Law-->WAV DEST--->File Writer. I only want to have a MONO 8KH CCITT a-Law in the output file. (or keep the sampling at the same as in the input filel). thanks in advance. here is the part of my code //----------------------------/ //getPin() is explained further IPin pPCMOut = GetPin((IBaseFilter)pACMWrap, PinDirection.Output, 0); IAMStreamConfig pPCMStreamConfig; pPCMStreamConfig = (IAMStreamConfig)pPCMOut; AMMediaType pMediaType = new AMMediaType(); pMediaType.majorType = MediaType.Audio; pMediaType.subType = MediaSubType.WAVE; WaveFormatEx pFormat = new WaveFormatEx(); //my audio setting pFormat.nSamplesPerSec = 64000; pFormat.nChannels = 1; pFormat.wBitsPerSample = 8000; //and here is the probleme, since I can't do : //WAVEFORMATEX* pFormat = (WAVEFORMATEX *)MediaType->pbFormat; //cause there is no pbFormat in DirectShowNet implementation //of AMMediaType class Marshal.PtrToStructure(pMediaType.formatPtr, pFormat); // ERROR: I'm having a null reference on formatPtr??? hr = pPCMStreamConfig.SetFormat(pMediaType); //----------------------------/ I'm stucked..can't get this working.. if you have any idea on how to solve this probleme...it will help a lot.. thanks in advance. regards, Walid Sign In·View Thread·PermaLink Re: how to configure output sampling rate and number of channels?? AlexMartins 1:02 25 Aug '08   Hello, I'm having the same problem and I think I have the solution for that. You have to allocate some memory space for the pMediaType.formatPtr like this: pMediaType.Ptr = Marshal.AllocCoTaskMem(Marshal.SizeOf(pFormat)); Now you don't have a NULL pointer, but an allocated pointer. This won´t give you the "ERROR: I'm having a null reference on formatPtr???" when you convert the pointer to the structure: Marshal.PtrToStructure(pMediaType.formatPtr, pFormat); Hope this help you. Have fun programming Sign In·View Thread·PermaLink Aleatory Error "Could Not setup grahp" lazartefederico 14:12 9 Jun '08   Dear... Sometimes, the Samplegraber.net works fine, but, if I restar the example, have this error: Could Not setup graph El Valor no esta dentro del intervalo esperado I close the application, run again, and the problem its resolver. I works with windows vista and a genius webcam. Can you help me? Thanks. Sign In·View Thread·PermaLink Why all the applications alert a message like "No video capture devices found!" during runtime rzzfch520 19:25 5 Jun '08   Please hlep me! Sign In·View Thread·PermaLink 1.00/5 (1 vote) why not just use tlbimp.exe to generate .NET wrapper interfaces for DirectShow? Member 2709805 7:01 2 Jun '08   The framework and samples you have created are very helpful, but I'm wondering why it was necessary to create the DShowNET project by hand -- couldn't this have been done using tlbimp.exe, the Microsoft-supplied utility? Or am I missing something? Sign In·View Thread·PermaLink Re: why not just use tlbimp.exe to generate .NET wrapper interfaces for DirectShow? [modified] NETMaster 8:04 2 Jun '08   DirectShow uses many non-oleautomation (=custom) COM interfaces. TLBIMP doesn't work well there. IMPORTANT: This code is 'obsolete' now, please use: Directshownet on sourceforge/[^] modified on Friday, June 6, 2008 8:13 AM Sign In·View Thread·PermaLink Thanks divyesh1432 21:35 25 May '08   excellent work dud thank you sooo much Sign In·View Thread·PermaLink Save avi without open mediacontrol window jotache 9:10 15 May '08   Hi everyone, i tried, using your sample, to save the webcam video input without open a videopanel, and I cant do that... Can you or something else give me a clue to do that? I was clear in what I want to do? Regards! Sign In·View Thread·PermaLink Re: Save avi without open mediacontrol window Jasper Gielen 5:15 26 May '08   Eventho it's a very very silly way of doing things, you could always just turn the visibility of the window itself to false. I'm trying to rewrite samplegrabber to the current version of directshow.net, but don't count on it. For now I'm using the suggested solution I'm giving you. If I'm able to rewrite it to current version, I'll be sure to publish it. Greets Sign In·View Thread·PermaLink

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