IQueueCommand interface (control.h)

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The IQueueCommand interface queues a command for processing at a designated time. The Filter Graph Manager exposes this interface. Applications can use it to queue graph-control commands in advance.

The methods in IQueueCommand are modeled after the IDispatch::InvokeAt method. The application specifies an interface, a method on the interface, parameters to the method, and a reference time. The Filter Graph Manager queues this information and then invokes the method at the specified time. The requested interface must inherit IDispatch and must be exposed by the Filter Graph Manager. Examples include IMediaControl, IMediaEventEx, and IMediaPosition.

When the command is queued, the filter graph manager returns a pointer to the IDeferredCommand interface. The application can use this interface to cancel or modify the command.

Note  The two methods in IQueueCommand refer to stream time and presentation time, respectively. In the context of the Filter Graph Manager, stream time and presentation time are identical, so there is no functional difference between the two methods. Other objects could implement IQueueCommand differently. For more information about stream time and presentation time, see Time and Clocks in DirectShow.

 

Inheritance

The IQueueCommand interface inherits from the IUnknown interface. IQueueCommand also has these types of members:

Methods

The IQueueCommand interface has these methods.

IQueueCommand::InvokeAtPresentationTime The InvokeAtPresentationTime method queues a method to be invoked at the specified presentation time.
IQueueCommand::InvokeAtStreamTime The InvokeAtStreamTime method queues a method or property change for execution at a specified stream time (that is, presentation time relative to the current stream time offset).

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	control.h (include Dshow.h)