MontiVision Project Files (*.mvp) contain all the information necessary to build a fully functional filter graph configuration. The first step to take when using the MV Smart Control for a vision application is to create a working "MVP" project file using the MV Worbench. Having created a fully functional graph in the MV Worbenchand saved it to an MVP file, you would be ready to load the project into your vision application. To do either load or save an MVP file, use the MV Smart Control's IMVSCFilterGraph interface and call either the LoadConfig() or the SaveConfig() method. The UnloadConfig() method removes the filter graph configuration from the control and frees all resources, for example capture sources.

Once you have loaded the configuration, you can control it's running state with the Start(), Stop() and Pause() methods available from the IMVSCFilterGraph interface. You also have full access to the filter graph with the FilterGraphManager property from IMVSCFilterGraph which contains a pointer to the IUnknown interface from the DirectShow filter graph manager. Use this interface to get the DirectShow interfaces from the filter graph manager (e.g. IFilterGraph2 or IMediaSeeking). To get the IUnknown interface from a filter, call the GetFilter() method from IMVSCFilterGraph with the filter name from the filter. This method is useful for retrieving a configuration interface from a DirectShow filter.

The last property from IMVSCFilterGraph is useful for debugging purposes. With the ExportFilterGraph property you can enable the export filter graph function from the MV Smart Control. If this property is enabled the MV Workbench will make the instantiated filter graph visible to the "Connect to Graph" command from the file menu.

Displaying a video stream

The window from the control can be used to display the video stream from a video renderer. If your filter graph configuration has more than one video renderer, use the RendererFilter property in the IMVSCVideoWindow interface to attach a video renderer to the control window. The IMVSCVideoWindow interface contains properties such as the UseAspectRatio, UseOriginalSize and Visible property. The VideoXResolution and VideoYResolution properties contains the original video stream resolution. To display the video without stretching set the control window size to the video resolution or use the UseOriginalSize property.

The IMVSCVideoWindow interface contains the MessageDrain property. The message drain is a window handle that receives all input device messages (e.g. WM_CHAR) from the video window.

The MontiVision Smart Control also supports full-screen display of video. The interface that caters for this is IMVSCFullScreen, which contains three properties: FullScreen, MonitorCount and Monitor. The MonitorCount property returns the number of available monitors while the Monitor property returns the current monitor used for the full-screen function. Set the FullScreen property to enable the full-screen feature.

Slave video window function

In some cases a vision application contains more than one video stream. To display all video streams in such an application, you will need to include one MontiVision Smart Control for each video stream. Use only one of these controls to load and control the filter graph (we will refer to this as the master control). The other controls are used as "slave video window controls". In such a scenario, call the SetVideoRenderer method from the IMVSCVideoWindow interface to configure these slave controls. The SetVideoRenderer method will need the filter graph manager and the video renderer's filter name as parameters. These can be retrieved from the master control by using the FilterGraphManager property of the IMVSCFilterGraph interface.

Changing the video source

A well-known caveat with DirectShow application development is the support for different video sources within one filter configuration. The MontiVision Smart Control solves this problem with the IMVSCSetSourceFilter interface which contains only one method: SetSourceFilter . This method replaces a video source filter, needing only the "Display Name" from the new video source and the name of the existing filter in the filter graph configuration. The "Display Name" from the new source filter describes in detail the video device. You can get the display name from the MV VideoSourceComboBox.

Not only is it now possible to change the video source, but it is also possible before or after loading a configuration file. It is recommended however that you reload a configuration after changing the source filter. If you change the device within a loaded configuration it is possible, that the MV Smart Control can't rebuild the filter graph.

Changing the video format

A video source can support many video formats. The MontiVision Smart Control exposes the IMVSCSetupVideoStream interface for purposes of making such changes.

To retrieve the video stream colour format (e.g. RGB24) use the GetVideoFormatCount and GetVideoFormatLabel methods.
To retrieve the video stream resolution use the GetVideoSizeInfoCount and GetVideoSizeInfo.
To set a new format call SetVideoFormat. The GetCurrentVideoFormat method returns the currently used video format.

You can also use the MV VideoFormatComboBox and MV VideoSizeComboBox the facilitate changes to the video format. It is not recommend that you change the video stream colour format because in some cases the MV Smart control will not be able to rebuild the filter graph after such a change. It is rather recommended that you allow DirectShow to select the best colour format from the device.

Selecting alternative inputs

Some capture devices have more than one video input. The IMVSCSelectInput interface from the MV Smart Control controls selection of these video inputs. You can use the MV SelectInputComboBox to select a video input. The other way is to use the methods from IMVSCSelectInput. Start with IsAvailable to check if a video device has more than one video inputs. Retieve the number of inputs with InputCount and enumerate them GetInputLabel. The CurrentConnection method returns the currently connected video input. To proceed with selecting a specific video input call the Connect method.

Changing files for File Sink and File Source filters

Filter graph configurations with file sink/source filter contain the path to the used file. To change these paths, the MV Smart Control exposes the IMVSCSetFile interface. For the file sink filter use the SetSinkFile and GetSinkFile methods and for the file source filter use the SetSourceFile and GetSourceFile methods. You can call the methods before or after loading a filter configuration. However, it is recommend that you set the filter to valid paths before you load a filter configuration. If the a file source/sink filter uses a invalid path the MV Smart Control will not be able to connect to these filters.

Changing the folder for the MV Batch Image File Source Filter

You can change the folder used by a MV Batch Image File Source Filter in the same way as you would the files for file sink/source filters. The IMVSCSetFile contains a SetBatchFolder and GetBatchFolder method to allow you to change the folder.

Open property dialogs from direct show filters

Most of the DirectShow Filters and all MontiVision Filters contains property pages to configure filter parameters. The IMVSCFilterProperties interface from the MontiVision Smart Control contains some methods to enumerate these filters and displays dialogs with the filter property pages. To to enumerate the filter with property pages call the GetPropertyPageName method. Open a dialog with the ShowProperties method. If you want to close a dialog call the CloseProperties method. It is not necessary to explicitly call CloseProperties because all dialogs are closed when the "OK" dialog button is pressed or if the filter configuration is unloaded.

Filter graph reference clock control

In some cases it is necessary to disable the reference clock in a filter graph. This might be necessary for example, if you wanted to process each frame of a video file. With the IMVSCClock interface you call setup the reference clock from a filter graph. Call the Disable method to disable the reference clock, and use SetDefault to return to using the default cock.

Handle Input Events from the Video Window

To handle input events from the video window such as mouse button clicks, set the IMVSCVideoWindow::EnableVideoWindowEvents property. This will allow you to handle the input events with the MV Smart Control Event Interface.

Log function

For debugging purposes the MontiVision Smart Control contains the IMVSCLog interface. It has two properties. The Enable property enables the log function and the Level property contains the minimum level for log messages. If the log function is enabled the MontiVision Smart Control calls the LogMessage method from the _IMVSmartControlEvents interface if a message is greater than or equal to the Level property.

Video Source Configuration

The IMVSCCameraControl interface contains methods to configure parameters such as contrast or brightness for a video source device. Use the methods in your application to change device parameters. The interface contains also methods to load and save all parameter from a video device into the registry.

Handle Events from MontiVision Imaging Filter

Lots of the MontiVision Imaging Filters fires events. The MontiVision Smart Control propagates these events to the application. Event notification is enabled with the IMVSCFilterEvents::Enable method. The _IMVSmartControlEvents::FilterEvent method is called on every event from an enabled MontiVision Imaging Filter.

Use Media Seeking on Video Files

To navigate within a movie file the MontiVision Smart Control provides the IMVSCMediaSeeking interface. It is based on the IMediaSeeking interface from DirectShow. To use this interface the MontiVision Development Kit contains the MV SeekingSlider Control.

Save Filter Parameter into the Registry

Most of the MontiVision Imaging Filters can load/save there parameter from/into the registry. The IMVSCFilterData interface from the MontiVision Smart Control provides methodd to load and save filter parameter for a filter from a filter configuration.

Get Video Processing Information

To obtain certain information about the video processing (such as the frame rate) the MontiVision Smart Control provides the IMVSCQualityProperties interface.