/// <summary>
/// Connects the filters of a previously created graph
/// (created by CreateGraph()). Once rendered the graph
/// is ready to be used. This method may also destroy
/// streams if we have streams we no longer want.
/// </summary>
void RenderGraph()
{
var didSomething = false;
// Stop the graph
_mediaControl?.Stop();
// Create the graph if needed (group should already be created)
CreateGraph();
// Derender the graph if we have a capture or preview stream
// that we no longer want. We can't derender the capture and
// preview streams seperately.
// Notice the second case will leave a capture stream intact
// even if we no longer want it. This allows the user that is
// not using the preview to Stop() and Start() without
// rerendering the graph.
if (!_wantPreviewRendered && _isPreviewRendered)
{
DerenderGraph();
}
// Render preview stream (only if necessary)
if (_wantPreviewRendered && !_isPreviewRendered)
{
// Render preview (video -> renderer)
var cat = PinCategory.Preview;
var med = MediaType.Video;
var hr = _captureGraphBuilder.RenderStream(cat, med, _videoDeviceFilter, _baseGrabFlt, null);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
// Get the IVideoWindow interface
_videoWindow = (IVideoWindow)_graphBuilder;
// Set the video window to be a child of the main window
hr = _videoWindow.put_Owner(PreviewWindow);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
// Set video window style
hr = _videoWindow.put_WindowStyle(WindowStyle.Child | WindowStyle.ClipChildren | WindowStyle.ClipSiblings);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
// Make the video window visible, now that it is properly positioned
hr = _videoWindow.put_Visible(OABool.True);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
_isPreviewRendered = true;
didSomething = true;
var media = new AMMediaType();
hr = _sampGrabber.GetConnectedMediaType(media);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
if (media.formatType != FormatType.VideoInfo || media.formatPtr == IntPtr.Zero)
{
throw new NotSupportedException("Unknown Grabber Media Format");
}
_videoInfoHeader = (VideoInfoHeader)Marshal.PtrToStructure(media.formatPtr, typeof(VideoInfoHeader));
Marshal.FreeCoTaskMem(media.formatPtr); media.formatPtr = IntPtr.Zero;
}
if (didSomething)
{
_actualGraphState = GraphState.Rendered;
}
}
/// <summary>
/// Create a new filter graph and add filters (devices, compressors, misc),
/// but leave the filters unconnected. Call RenderGraph()
/// to connect the filters.
/// </summary>
void CreateGraph()
{
//Skip if already created
if ((int)_actualGraphState < (int)GraphState.Created)
{
// Make a new filter graph
_graphBuilder = (IGraphBuilder) new FilterGraph();
// Get the Capture Graph Builder
_captureGraphBuilder = (ICaptureGraphBuilder2) new CaptureGraphBuilder2();
// Link the CaptureGraphBuilder to the filter graph
var hr = _captureGraphBuilder.SetFiltergraph(_graphBuilder);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
var comObj = new SampleGrabber();
_sampGrabber = (ISampleGrabber)comObj;
_baseGrabFlt = (IBaseFilter)_sampGrabber;
var media = new AMMediaType();
// Get the video device and add it to the filter graph
if (VideoDevice != null)
{
_videoDeviceFilter = (IBaseFilter)Marshal.BindToMoniker(VideoDevice.MonikerString);
hr = _graphBuilder.AddFilter(_videoDeviceFilter, "Video Capture Device");
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
media.majorType = MediaType.Video;
media.subType = MediaSubType.RGB32; //RGB24;
media.formatType = FormatType.VideoInfo;
media.temporalCompression = true; //New
hr = _sampGrabber.SetMediaType(media);
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
hr = _graphBuilder.AddFilter(_baseGrabFlt, "Grabber");
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
}
// Retrieve the stream control interface for the video device
// FindInterface will also add any required filters
// (WDM devices in particular may need additional
// upstream filters to function).
// Try looking for an interleaved media type
var cat = PinCategory.Capture;
var med = MediaType.Interleaved;
var iid = typeof(IAMStreamConfig).GUID;
hr = _captureGraphBuilder.FindInterface(cat, med, _videoDeviceFilter, iid, out var o);
if (hr != 0)
{
// If not found, try looking for a video media type
med = MediaType.Video;
hr = _captureGraphBuilder.FindInterface(cat, med, _videoDeviceFilter, iid, out o);
if (hr != 0)
{
// ReSharper disable once RedundantAssignment
o = null;
}
}
//VideoStreamConfig = o as IAMStreamConfig;
// Retreive the media control interface (for starting/stopping graph)
_mediaControl = (IMediaControl)_graphBuilder;
// Reload any video crossbars
//if (videoSources != null) videoSources.Dispose(); videoSources = null;
_videoInfoHeader = Marshal.PtrToStructure <VideoInfoHeader>(media.formatPtr);
Marshal.FreeCoTaskMem(media.formatPtr); media.formatPtr = IntPtr.Zero;
hr = _sampGrabber.SetBufferSamples(true);
if (hr == 0)
{
hr = _sampGrabber.SetOneShot(false);
}
if (hr == 0)
{
hr = _sampGrabber.SetCallback(null, 0);
}
if (hr < 0)
{
Marshal.ThrowExceptionForHR(hr);
}
}
// Update the state now that we are done
_actualGraphState = GraphState.Created;
}
