ADLINK Technology HDV62, User Manual

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Programming Guide 89
5 Programming Guide
5.1 Introduction
Complete documentation on DirectShow application programming
can be found at http://msdn.microsoft.com/en-us/library/
dd390351(VS.85).aspx. If a DirectX SDK is installed, this docu-
mentation is also available from DirectX SDK Help. The last ver-
sion of DirectShow SDK was moved to Windows SDK.
The main goal of writing a DirectShow Application is to build a filter
graph by connecting several filters together to perform a given
task such as previewing video/audio, capturing video/audio and
multiplexing them to write into a file. Each filter performs a single
operation and pass data from its output pin to the input pin of the
next filter in the graph.
To build a capture graph using a program, the first thing is to
obtain the interface pointer of the capture filter. The ADLINK
HDV62 Video Capture filter and the ADLINK HDV62 Crossbar fil-
ter can be obtained through
system device enumerator . After
holding an interface pointer to the capture filter object, use method
IGraphBuilder::AddSourceFilter to add the source filter object to
the filter graph. Use IFilterGraph::AddFilter to add other down-
stream filters to the filter graph. After filters are added, call IFilter-
Graph::ConnectDirect or IGraphBuilder::Connect methods to
connect output pins from upstream filters to the input pins of the
downstream filters. Call
IAMCrossbar::Route to switch source
channel. Calling methods IMediaControl::Run , IMediaCon-
trol::Pause or IMediaControl::Stop will change filter state to run-
ning, paused or stopped.
The filters that are needed for capturing video streams are listed in
next section, with detailed information for each filter and its pins.
Example filter graphs for capturing video streams are also illus-
trated in this chapter and gives examples of two ways of control-
ling device driver.