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ILMVCallback Interface

This is the interface for the LEAD Video Callback Filter.

Interface Properties:

Type	Name	Description
VARIANT	InputPalette	[read-only] Use this property to read the input palette. This is valid only for videos that have an input palette (usually 8-bit). The variant is returned as an array of bytes (VT_ARRAY \| VT_UI1).
VARIANT	OutputPalette	Use this property to view and change the output palette. Keep in mind that when you change the output palette, the output pin will attempt to reconnect. It is recommended you rebuild the graph after you change the output palette to avoid broken graphs. The variant should be an array of bytes (VT_ARRAY \| VT_UI1).
double	CurrentPosition	[read-only] Use this property to get the position (in seconds) of the current sample passed to the callback. It is recommended you call this property to get the current position from inside ILMVUserCallback::ReceiveProc rather than trying to get the current position from the graph or LTMM object.
long	CurrentFramePosition	[read-only] Use this property to get the frame number of the current sample passed to the callback. It is recommended you call this property to get the current position from inside ILMVUserCallback::ReceiveProc rather than trying to get the current position from the graph or LTMM object.
VARIANT_BOOL	CallInSameThread	Enables or disables the calling of the CallbackProc notifications in the same thread that set the ReceiveProcObj property. The default value is VARIANT_TRUE. Possible values are:
		Value	Meaning
		VARIANT_TRUE	Call the notifications in the same thread that set the callback. This reduces the performance and requires the application to process messages, otherwise the callback will not get called. It is the default and is required for platforms that have problem with multithreading. VB 6.0 and dotnet applications should use this mode.
		VARIANT_FALSE	Call the notifications in any thread of the process. Use this setting for best performance in platforms that can handle this. This is the recommended mode for C++ applications.

Interface Methods:

HRESULT put_ReceiveProcObj(IUnknown *pCallback)

Parameters

pCallback

a valid pointer to an object that implements the ILMVCallback interface.

Description

(Write-only) Sets the callback object pointer.
If not NULL, the ReceiveProc method of this interface will be called with every video buffer.
Set to NULL (or to "Nothing" in VB) if you do not wish to receive notifications anymore. (For example, before you delete (release) the callback object interface).

Return

S_OK if successful, S_FALSE otherwise.

HRESULT SetFOURCCEnabled(long lFOURCC, VARIANT_BOOL bAccept)

Parameters

lFOURCC	FOURCC code value of the media format.
bAccept	A Boolean value that indicates whether to accept the media type of the supplied FOURCC code. TRUE to accept; otherwise, false.

Description

Enables or disables accepting the media type of the corresponding FOURCC code as the input media type for the filter.
Note: Call the method before rebuilding the graph in order for the graph to reflect whether to accept the media type of the supplied FOURCC code.
Setting the value of lFOURCC to 0 means that the method will target all the RGB formats.

Return

S_OK if successful; otherwise, S_FALSE.

HRESULT GetFOURCCEnabled(long lFOURCC, VARIANT_BOOL* pbAccept)

Parameters

lFOURCC	FOURCC code value of the media format.
pbAccept	Pointer to a variable that will receive the state of the supplied FOURCC. TRUE indicates that the media type of the corresponding FOURCC is accepted as the input media type for the filter. FALSE indicates that the media type of the corresponding FOURCC is disabled and will not be accepted.

Description

Retrieves the state of a FOURCC code which indicates whether a media type is accepted as the input type for the filter.
Setting the value of lFOURCC to 0 means that the method will target all the RGB formats.