CDynamicOutputPin.Block 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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 Block method blocks or unblocks the flow of data from the pin. This method implements the IPinFlowControl::Block method.

Syntax

HRESULT Block(
   DWORD  dwBlockFlags,
   HANDLE hEvent
);

Parameters

dwBlockFlags

Flag that indicates whether to block or unblock the pin. Must be one of the following values:

Zero: Unblock data flow from the pin.

AM_PIN_FLOW_CONTROL_BLOCK: Block data flow from the pin.

hEvent

Handle to an event object, or NULL.

Return value

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

Return code	Description
S_FALSE	Pin is already unblocked.
S_OK	Success.
E_INVALIDARG	Invalid argument.
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

For more information about this method, see IPinFlowControl::Block. Internally, this method calls one of the following protected methods:

• Block (asynchronous): CDynamicOutputPin::AsynchronousBlockOutputPin
• Block (synchronous): CDynamicOutputPin::SynchronousBlockOutputPin
• Unblock: CDynamicOutputPin::UnblockOutputPin

Unblocking is always performed synchronously.

Requirements

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

See also

CDynamicOutputPin Class