CMsg class

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 CMsgThread class provides support for a worker thread to which requests can be posted asynchronously instead of sent directly. The CAMThread class provides a worker thread to which single requests can be sent. Only one client can make a request at a time, and the client blocks until the worker thread has completed the request. By contrast, the CMsgThread class provides a worker thread to which any number of requests can be posted. The requests (in the form of a CMsg object) are queued and executed in order, asynchronously. No reply or return value is received.

Data Members	Description
dwFlags	Flag parameter to the request code.
lpParam	Data required by the worker thread as parameter or return values. This data should not be stack-based, as it will be referenced some time after completing the queuing operation.
pEvent	Event object that a worker thread can signal to indicate the completion of the operation.
uMsg	Request code that is defined by the client of the thread class and understood by the overridden worker thread function.
Member Functions	Description
CMsg	Constructs a CMsg object.