/// <summary>
/// Build the graph and connect filters
/// </summary>
/// <param name="outputPath">Path of stego video file</param>
private void BuildGraph(string outputPath)
{
///Create a graph builder.
this._graphBuilder = (IGraphBuilder) new FilterGraph();
///Create a sample grabber filter. Sample grabber filter provides callback
///for application to grab video frames on the fly.
this._sampleGrabber = (ISampleGrabber) new SampleGrabber();
///Configure the sample grabber
this.ConfigureSampleGrabber(this._sampleGrabber, MediaSubType.RGB24);
///Create the file reader filter.
this._fileReaderFilter = ComGuids.GetFilterFromGuid(ComGuids.FileReaderFilterGuid);
///Add the filter to graph. This function only adds filter to graph but
///do not connect it
this._graphBuilder.AddFilter(this._fileReaderFilter, "File Source");
///Get source filter, this will let you load an AVI file
IFileSourceFilter sourceFilter = this._fileReaderFilter as IFileSourceFilter;
///Load the file
sourceFilter.Load(this._sourcePath, null);
///Create AVI splitter. This filter splits the AVI file into video and audio or other
///components that form the video (e.g text)
this._aviSplitter = ComGuids.GetFilterFromGuid(ComGuids.AviSplitterGuid);
///Add the filter to graph
this._graphBuilder.AddFilter(this._aviSplitter, "AVI Splitter");
///Add the sample grabber filter to graph
this._graphBuilder.AddFilter((IBaseFilter)this._sampleGrabber, "SampleGrabber");
///Create AVI mux filter. This filter will combine the audio and video in one stream.
///We will use this filter to combine audio and video streams after hiding
///data in ISampleGrabber's BufferCB callback.
this._aviMultiplexer = ComGuids.GetFilterFromGuid(ComGuids.AviMultiplexerGuid);
///Add filter to graph
this._graphBuilder.AddFilter(this._aviMultiplexer, "AVI multiplexer");
///We will add file writer, only then we will add file writer
if (this._processing == ProcessingType.Hide)
{
///Create a file writer filter. This filter will be used to write the AVI stream
///to a file
this._rendererFilter = ComGuids.GetFilterFromGuid(ComGuids.FileWriterFilterGuid);
///Add renderer filter to graph
this._graphBuilder.AddFilter(this._rendererFilter, "File writer");
///Get the file sink filter
IFileSinkFilter sinkFilter = this._rendererFilter as IFileSinkFilter;
///Set the output file name
sinkFilter.SetFileName(outputPath, null);
}
else
{
///Create a null renderer
this._rendererFilter = ComGuids.GetFilterFromGuid(ComGuids.NullRendererGuid);
///Add renderer filter to graph
this._graphBuilder.AddFilter(this._rendererFilter, "Null renderer");
}
DirectShowUtil.ConnectFilters(this._graphBuilder, this._fileReaderFilter, this._aviSplitter);
DirectShowUtil.ConnectFilters(this._graphBuilder, this._aviSplitter, (IBaseFilter)this._sampleGrabber);
DirectShowUtil.ConnectFilters(this._graphBuilder, (IBaseFilter)this._sampleGrabber, this._aviMultiplexer);
DirectShowUtil.ConnectFilters(this._graphBuilder, this._aviMultiplexer, this._rendererFilter);
}