CDynamicOutputPin.AsynchronousBlockOutputPin method

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 AsynchronousBlockOutputPin method blocks the pin. The method might return before the pin is blocked.

Syntax

HRESULT AsynchronousBlockOutputPin(
   HANDLE hNotifyCallerPinBlockedEvent
);

Parameters

hNotifyCallerPinBlockedEvent

Handle to an event. The event is signaled when the output pin is blocked, or if the caller cancels the block operation.

Return value

Returns an HRESULT value. Possible values include those shown in the following table.

Return code	Description
S_OK	Success.
VFW_E_PIN_ALREADY_BLOCKED	Pin is already blocked on another thread.
VFW_E_PIN_ALREADY_BLOCKED_ON_THIS_THREAD	Pin is already blocked on the calling thread.

Remarks

Do not call this method from the streaming thread.

If no streaming thread is using the pin, this method immediately blocks the pin. Otherwise, it sets the pin status to "pending" and returns. When the streaming operation completes, the streaming thread calls the CDynamicOutputPin::StopUsingOutputPin method, which blocks the pin and signals the hNotifyCallerPinBlockedEvent event. To cancel a pending block, call the CDynamicOutputPin::UnblockOutputPin method.

Requirements

Requirement	Value
Header	Amfilter.h (include Streams.h)
Library	Strmbase.lib (retail builds); Strmbasd.lib (debug builds)

See also

CDynamicOutputPin Class