CBaseControlVideo Class

Article
06/30/2006

This class implements the IBasicVideo dual interface and controls the video properties of a generic video window. Generally, a CBaseControlVideo object is a video renderer that draws video into a window on the display.

The CBaseControlVideo class supports both properties and methods. Properties are more easily accessible from many Automation controllers (such as the Microsoft Visual Basic® programming system). However, some operations require applications to be able to change several properties simultaneously; for this reason, methods are provided that enable a number of related properties to be changed.

Many CBaseControlVideo member functions require only that the video renderer be connected to a filter graph. If it is not connected, member functions will return VFW_E_NOT_CONNECTED. Properties set on a video renderer persist between successive connections and disconnections. All applications should ensure that they reset the renderer properties before starting a presentation.

When working with video, the application can select a portion of the video to use. This portion is the source rectangle that the CBaseControlVideo object controls. CBaseControlVideo enables your application to set and retrieve the source rectangle. All the rectangles that CBaseControlVideo uses employ top, left, width, and height rather than top, left, right, and bottom, which is favored in Win32 programming. When no source rectangle has been set, the properties of the source rectangle return the full, native video size.

Protected Data Members

Member	Description
m_pFilter	Pointer to an owning media filter.
m_pInterfaceLock	Externally defined critical section.
m_pPin	Control of the media types for connection.

Member Functions

Member function	Description
CBaseControlVideo	Constructs a CBaseControlVideo object.
CopyImage	Creates a memory copy of a video image.
GetImageSize	Retrieves video image size information.
SetControlVideoPin	Sets the pin with which this object should synchronize.

Overrideable Member Functions

Member function	Description
CheckSourceRect	Determines if a source rectangle is valid.
CheckTargetRect	Determines if a target rectangle is valid.
GetSourceRect	Retrieves the current source video rectangle as a pure virtual function.
GetStaticImage	Returns the current image in a memory buffer as a pure virtual function.
GetTargetRect	Retrieves the current target video rectangle as a pure virtual function.
GetVideoFormat	Retrieves the VIDEOINFOHEADER structure containing the video format.
IsDefaultSourceRect	Determines if the renderer is using the default source rectangle as a pure virtual function.
IsDefaultTargetRect	Determines if the renderer is using the default target rectangle as a pure virtual function.
OnUpdateRectangles	Called when the source or target rectangle changes.
OnVideoSizeChange	Passes EC_VIDEO_SIZE_CHANGED to the application.
SetDefaultSourceRect	Sets the default source video rectangle as a pure virtual function.
SetDefaultTargetRect	Sets the default target video rectangle as a pure virtual function.
SetSourceRect	Sets the current source video rectangle as a pure virtual function.
SetTargetRect	Sets the current target rectangle as a pure virtual function.

Implemented IBasicVideo Methods

Method	Description
get_AvgTimePerFrame	Retrieves an approximate average time per frame.
get_BitErrorRate	Retrieves an approximate bit error rate.
get_BitRate	Retrieves an approximate bit rate for the video.
GetCurrentImage	Retrieves a memory rendering of the current image.
get_DestinationHeight	Retrieves the current destination rectangle's height.
get_DestinationLeft	Retrieves the current destination rectangle's left coordinate.
GetDestinationPosition	Retrieves the current destination position.
get_DestinationTop	Retrieves the current destination rectangle's top coordinate.
get_DestinationWidth	Retrieves the current destination rectangle's width.
get_SourceHeight	Retrieves the current source rectangle's height.
get_SourceLeft	Retrieves the current source rectangle's left coordinate.
GetSourcePosition	Retrieves the current source position.
get_SourceTop	Retrieves the current source rectangle's top coordinate.
get_SourceWidth	Retrieves the current source rectangle's width.
get_VideoHeight	Retrieves the native video height.
GetVideoPaletteEntries	Retrieves a range of palette entries for the video.
GetVideoSize	Retrieves the width and height of the native video.
get_VideoWidth	Retrieves the native video width.
IsUsingDefaultDestination	Determines if the renderer is using the default destination window.
IsUsingDefaultSource	Determines if the renderer is using the default source window.
put_DestinationHeight	Sets the destination rectangle's height.
put_DestinationLeft	Sets the destination rectangle's left coordinate.
put_DestinationTop	Sets the destination rectangle's top coordinate.
put_DestinationWidth	Sets the destination rectangle's width.
put_SourceHeight	Sets the source rectangle's height.
put_SourceLeft	Sets the source rectangle's left coordinate.
put_SourceTop	Sets the source rectangle's top coordinate.
put_SourceWidth	Sets the source rectangle's width.
SetDefaultDestinationPosition	Sets the default destination position again.
SetDefaultSourcePosition	Sets the default source position again.
SetDestinationPosition	Sets the destination rectangle position.
SetSourcePosition	Sets the source rectangle position.

Requirements

DirectShow applications and DirectShow filters have different include file and link library requirements. See Setting Up the Build Environment for more information.

OS Versions: Windows CE 2.12 and later. Version 2.12 requires DXPAK 1.0 or later.
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Last updated on Wednesday, April 13, 2005

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