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.

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.

See Also

• Data Flow in the Filter Graph
• Error and Success Codes
• IPin Interface