IDistributorNotify Interface
The IDistributorNotify interface is an optional interface for use by plug-in distributors to notify them of changes in the filter graph state.
Implement this interface when writing a plug-in distributor (PID) that is aggregated with the filter graph manager if you want the PID to receive notifications of control and changes in the composition of filter graphs.
PIDs might often use methods on the filter graph manager. During a call to an IDistributorNotify method, do not take any lock that might be held by another code path that calls the filter graph manager. To do so could result in a deadlock.
The filter graph manager queries for this interface on any plug-in distributors that it aggregates. If found, it calls the appropriate Run, Pause, or SetSyncSource method before calling them on the IBaseFilter interface of each filter. It calls the NotifyGraphChange method whenever a filter is added or removed, or connections are changed.
Methods in Vtable Order
IUnknown methods Description QueryInterface Retrieves pointers to supported interfaces. AddRef Increments the reference count. Release Decrements the reference count. IDistributorNotify methods Description Stop Called when the filter graph is entering a stopped state. Pause Called when the filter graph is entering a paused state. Run Called when the filter graph is entering a running state. SetSyncSource Called when a new clock is registered. NotifyGraphChange Called when the set of filters in the filter graph change or their connections change.
IDistributorNotify::NotifyGraphChange
Called when the set of filters in the filter graph change or their connections change.
Syntax
HRESULT NotifyGraphChange(void);
Return Value
Returns an HRESULT value that depends on the implementation. HRESULT can be one of the following standard constants, or other values not listed:
E_FAIL Failure. E_POINTER Null pointer argument. E_INVALIDARG Invalid argument. E_NOTIMPL Method isn't supported. S_OK or NOERROR Success.
Remarks
This method is called whenever an IFilterGraph::AddFilter, IFilterGraph::RemoveFilter, or IFilterGraph::ConnectDirect method is called or a method is called that will lead to one of these being called (such as IGraphBuilder::RenderFile).
Make sure you use Release on any held filters that have been removed at this point. For performance reasons, PIDs might choose not to rescan the filters until the PIDs actually need the interfaces, because there might be several separate notifications sent. However, it is important to release any cached interfaces immediately.
IDistributorNotify::Pause
Called when the filter graph is entering a paused state.
Syntax
HRESULT Pause(void);
Return Value
Returns S_OK if the transition is complete; otherwise, returns one of the following values.
Error value Transition failed. S_FALSE Transition is not complete, but no error has occurred.
Remarks
This method is called before the filters are notified.
IDistributorNotify::Run
Called when the filter graph is entering a running state.
Syntax
HRESULT Run(
REFERENCE_TIME tStart
);
Parameters
- tStart
- Stream-time offset that will be passed to every filter's IBaseFilter::Run parameter.
Return Value
Returns an HRESULT value that depends on the implementation. HRESULT can be one of the following standard constants, or other values not listed.
E_FAIL Failure. E_POINTER Null pointer argument. E_INVALIDARG Invalid argument. E_NOTIMPL Method isn't supported. S_OK or NOERROR Success.
Remarks
This method is called before the filters are notified.
IDistributorNotify::SetSyncSource
Called when a new clock is registered.
Syntax
HRESULT SetSyncSource(
IReferenceClock *pClock
);
Parameters
- pClock
- [in] Pointer to the IReferenceClock interface.
Return Value
Returns an HRESULT value that depends on the implementation. HRESULT can be one of the following standard constants, or other values not listed.
E_FAIL Failure. E_POINTER Null pointer argument. E_INVALIDARG Invalid argument. E_NOTIMPL Method isn't supported. S_OK or NOERROR Success.
Remarks
This method is called before the filters are notified. Make sure to use AddRef on the pClock parameter if the plug-in distributor intends to hold it beyond this method call.
IDistributorNotify::Stop
Called when the filter graph is entering a stopped state.
Syntax
HRESULT Stop(void);
Return Value
Returns S_OK if the transition is complete; otherwise, returns one of the following values.
Error value Transition failed. S_FALSE Transition is not complete, but no error has occurred.
Remarks
This method is called before the filters are notified.
Top of Page
© 2000 Microsoft and/or its suppliers. All rights reserved. Terms of Use.