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4/8/2010

DirectShow supports system-defined events, which filters in the filter graph pass to the Filter Graph Manager.

Filters pass these events to the Filter Graph Manager by using the IMediaEventSink::Notifymethod, and the application retrieves them with the IMediaEvent::GetEventmethod.

When you retrieve an event by calling GetEvent, the event can contain interface pointers or pointers to allocated memory. Code that uses GetEventshould, therefore, call IMediaEvent::FreeEventParamsto free any resources associated with the event's parameters after it handles the event.

The system-defined event notification codes are listed in the Evcode.h header file.

The parameters listed with an event notification code are the ones passed with the code in the CBaseFilter::NotifyEventfunction. For example, consider the following statements.

Copy Code
NotifyEvent(EC_OLE_EVENT, (DWORD) bstr, NULL);
NotifyEvent(EC_COMPLETE, S_OK, 0);
NotifyEvent(EC_ERRORABORT, E_FAIL, 0);

Event notification code Description

EC_ACTIVATE

An audio or video renderer is losing or gaining activation.

EC_BUFFER_FULL

Indicates that the capture buffer is full.

EC_BUFFERING_DATA

The buffering status is changing.

EC_CAP_FILE_COMPLETED

This notification indicates that still image capture has completed.

EC_CAP_FILE_WRITE_ERROR

Indicates that an error occurred while writing captured data to a file.

EC_CAP_SAMPLE_PROCESSED

Indicates that a frame of data has been captured.

EC_CLOCK_CHANGED

The filter graph has changed from one reference clock to another.

EC_COMPLETE

All data has been rendered.

EC_DRM_LEVEL

Notifies when content protected by digital rights management (DRM) requests some form of analog content protection.

EC_END_OF_SEGMENT

Notifies that a segment end has been reached.

EC_ERROR_STILLPLAYING

At least one call to Runfailed in an active filter graph.

The current state of any underlying filter graph or graphs is indeterminate; they might be running, but some are almost certainly not.

EC_ERRORABORT

An error forced the termination of a requested operation.

EC_FULLSCREEN_LOST

The video renderer is switching out of full-screen mode.

EC_NEED_RESTART

The current graph must be stopped and restarted.

EC_NOTIFY_WINDOW

Pass the window handle around during pin connection.

EC_OLE_EVENT

A filter is passing a text string to the application.

EC_OPENING_FILE

The open file status is changing.

EC_PLAY_NEXT

The user has initiated an asynchronous request to play back the next track.

EC_PLAY_PREVIOUS

The user has initiated an asynchronous request to play back the previous track.

EC_PALETTE_CHANGED

The video palette has changed.

EC_QUALITY_CHANGE

The playback quality has changed.

EC_REPAINT

A repaint is required.

EC_SEGMENT_STARTED

Notifies that a new segment has been started.

EC_SHUTTING_DOWN

The filter graph is starting to shut down.

DirectShow passes this notification to any plug-in distributors that support the IMediaEventSinkinterface.

EC_STARVATION

One of the filters (usually a parser or file source filter) is not receiving enough data.

By default, the filter graph manager will pause all running filters and then return to normal operation when enough data is available.

EC_STREAM_CONTROL_STARTED

The starting reference time from an earlier call to IAMStreamControl::StartAtpassed.

EC_STREAM_CONTROL_STOPPED

The stopping reference time from an earlier call to IAMStreamControl::StopAtpassed.

EC_STREAM_ERROR_STILLPLAYING

The stream is still playing, but should not be playing.

EC_STREAM_ERROR_STOPPED

The stream has stopped, but should not have stopped.

EC_TIME

The requested reference time occurred.

EC_USERABORT

A user has forced the termination of a requested operation.

EC_VIDEO_SIZE_AR_CHANGED

The size or aspect ratio of the native video has changed.

EC_VIDEO_SIZE_CHANGED

The size of the native video has changed.

EC_WINDOW_DESTROYED

The video renderer's filter is being removed or destroyed.

See Also

Reference

DirectShow Macros