|Microsoft DirectX 9.0|
The BeginFlush method begins a flush operation.
virtual HRESULT BeginFlush(void);
Returns S_OK or another HRESULT value.
At the start of a flush operation, the input pin's CTransformInputPin::BeginFlush method calls this method. This method passes the BeginFlush call downstream.
If the derived class uses a worker thread to deliver samples, it should discard any queued data during a flush operation. That can be done either in the BeginFlush method, or in the EndFlush method. However, note that calls to BeginFlush are not synchronized with the streaming thread. If the BeginFlush method discards the queued data, the filter must be careful not to process any more data between the BeginFlush and EndFlush calls. For more information, see Data Flow for Filter Developers.