C# Playing Video From A Memory Stream Using DirectShow (quartz.dll).

Question

I have a C# Visual Studio WinForms app that plays video using the QuartzTypeLib (quartz.dll). With the code I've written, I can play any video file from the hard drive. Here's the code at the top that executes when the app starts:
        public const int WS_CHILD = 0x40000000;
        public const int WS_CLIPCHILDREN = 0x2000000;
        public QuartzTypeLib.IMediaControl mc;
        public QuartzTypeLib.IVideoWindow videoWindow = null;
        IMediaPosition mp = null;
And here's the code that opens the video file:
        private void openMediaToolStripMenuItem_Click(object sender, EventArgs e)
            // Open a media file.
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "Video Files|*.mpg;*.avi;*;*.wmv;*.mov";
            ofd.FilterIndex = 1;
            if (DialogResult.OK == ofd.ShowDialog())
                // Stop the playback for the current movie if a video is currently playing.
                if (mc != null)
                    mc.Stop();
                if (pbVideoDisplay.Image != null)
                    pbVideoDisplay.Image = null;
                // Load the movie file.
                FilgraphManager graphManager = new FilgraphManager();
                graphManager.RenderFile(ofd.FileName);
                mp = graphManager as IMediaPosition;
                mc = (IMediaControl)graphManager;
                tsbtnPlay.Enabled = tsbtnPause.Enabled = tsbtnStop.Enabled = true;
                // Attach the view to the picture box (pbVideoDisplay) on frmMain.
                try
                    videoWindow = (IVideoWindow)graphManager;
                    videoWindow.Owner = (int)pbVideoDisplay.Handle;
                    videoWindow.WindowStyle = WS_CHILD | WS_CLIPCHILDREN;
                    videoWindow.SetWindowPosition(
                    pbVideoDisplay.ClientRectangle.Left,
                    pbVideoDisplay.ClientRectangle.Top,
                    pbVideoDisplay.ClientRectangle.Width,
                    pbVideoDisplay.ClientRectangle.Height);
                catch //(Exception Ex)
                    // I'll write code for this when I have a need to.
                // Now we convert the video to a byte array.
                FileStream fs = new FileStream(ofd.FileName, FileMode.Open, FileAccess.Read);
                try
                    // Here we convert the video to Base 64.
                    VideoInBytes = new byte[fs.Length];
                    VideoInBytes = System.Text.Encoding.UTF8.GetBytes(ofd.FileName);
                    VideoInBase64 = Convert.ToBase64String(VideoInBytes);
                catch //(Exception Ex)
                    //throw new Exception("Error in base64Encode" + Ex.Message); Worry about this later.
Notice that I have code that converts the video to a Base64 string. I'd like to add code that will allow me to play a video from a memory stream or any other type of stream that might work better. Is that even possible and if so, what code would I need to add
and where would I put it?

Answer 1

You should be able to do it by developing a plug-in for the existing DShow filter. For instance, wmv files are being opened/read with the "WM ASF Reader" filter. You can register your own protocol and implement your own plug-in for that protocol
(e.g. you could name it 'memory', and your URL would look like
memory://something.wmv). You can register your protocol under the [HKEY_CLASSES_ROOT\memory\Extensions] by creating a new string value with the file extension as a name (.wmv). The value is the WM ASF Readers's
GUID ({187463A0-5BB7-11D3-ACBE-0080C75E246E}).
You also need to register your plugin that will be used for a wmv file when used with the 'memory' protocol.
In [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Media\WMSDK\sources] create a new string value with the protocol name and the value is a path to you DLL plug-in. Your plug-in must implement the IStream interface. The plugin DLL exports a single function:
HRESULT WMCreateStreamForURL( LPCWSTR pwszURL, BOOL *pfCorrectSource, IStream **ppStream )
MSDN can provide more info on WMCreateStreamForURL() and plugins in general.
Once you do that, what will happen is this: each time you open a file like "memory://myfile.wmv", the WM ASF Reader filter will load your plugin, call WMCreateStreamForURL() and it will use your custom IStream object for all read/write operations.