IPin::BeginFlush

  • Articolo
 
Microsoft DirectShow 9.0

IPin::BeginFlush

The BeginFlush method begins a flush operation.

Applications should not call this method. This method is called by other filters, to flush data from the graph.

Syntax

  HRESULT BeginFlush(void);

Return Value

Returns an HRESULT value. Possible values include the following.

Value Description
S_OK Success.
E_UNEXPECTED The pin is an output pin.

Remarks

Call this method only on input pins. Output pins return E_UNEXPECTED.

In a flush operation, a filter discards whatever data it was processing. It rejects new data until the flush is completed. The flush is completed when the upstream pin calls the IPin::EndFlush method. Flushing enables the filter graph to be more responsive when events alter the normal data flow. For example, flushing occurs during a seek.

When BeginFlush is called, the filter performs the following steps:

  1. Passes the IPin::BeginFlush call downstream.
  2. Sets an internal flag that causes all data-streaming methods to fail, such as IMemInputPin::Receive.
  3. Returns from any blocked calls to the Receive method.

When the BeginFlush notification reaches a renderer filter, the renderer frees any samples that it holds.

After BeginFlush is called, the pin rejects all samples from upstream, with a return value of S_FALSE, until the IPin::EndFlush method is called.

Requirements

Header: Declared in Strmif.h; include Dshow.h.

Library: Use Strmiids.lib.

See Also