ILMFVCallback Interface

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This is the interface for the LEAD Video Callback Transform.

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 media type will change and will attempt to reset. It is recommended you rebuild the topology after you change the output palette to avoid broken topology. 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 topology or LTMF 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 topology or LTMF 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 a user callback interface interface.

Description

(Write-only) Sets the callback object pointer.

If not NULL, the ReceiveProc method of this interface will be called with every audio 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 otherwis.

HRESULT ResetToDefaults()

Parameters

None.

Description

Resets the Video Callback transform values to their default values.

Return

S_OK if successful, S_FALSE otherwis.

HRESULT LoadAttributes()

Parameters

None.

Description

Loads transform settings from the registry. The Media Foundation transforms import the settings from the registry only at creation time. This method will force the transform to re-load its settings from the registry. If the transform has no settings to load from the registry, E_NOTIMPL is returned.

Return

S_OK if successful, S_FALSE otherwis.

HRESULT SaveAttributes()

Parameters

None.

Description

Writes transform settings to the registry. This method will force the transform to save its settings to the registry before its released.

If the transform has no settings to write to the registry, E_NOTIMPL is returned..

Return

S_OK if successful, S_FALSE otherwis.