Microsoft DirectX 9.0

IAMTimelineComp Interface

The IAMTimelineComp interface inserts or retrieves virtual tracks on a composition in DirectShow Editing Services (DES).

A composition is a collection of layers that acts as a single, composited track. For example, a composition that contains two tracks with a transition between them acts as a single track with the transition precomposited. A composition should contain media of only one type (such as audio or video), but this limitation is not enforced. A virtual track is any object that can reside in a composition, including tracks and other compositions.

The topmost nodes in the timeline are groups. Groups implement both the IAMTimelineComp interface and the IAMTimelineGroup interface.

To create a composition object, call IAMTimeline::CreateEmptyNode with the value TIMELINE_MAJOR_TYPE_COMPOSITE. You can query the returned IAMTimelineObj pointer for the IAMTimelineComp interface. For more information, see The Timeline Model and Constructing a Timeline.

In addition to the methods inherited from IUnknown, the IAMTimelineComp interface exposes the following methods.

Method Description
GetCountOfType Retrieves the number of objects of a given type contained in this composition and all of its virtual tracks, recursively.
GetNextVTrack Retrieves the next virtual track after a specified virtual track.
GetRecursiveLayerOfType Performs a depth-first ordering of the virtual tracks contained in this composition, and retrieves the nth virtual track from that ordering.
GetRecursiveLayerOfTypeI Not supported.
GetVTrack Retrieves the virtual track at the specified priority.
VTrackGetCount Retrieves the number of virtual tracks contained in the composition.
VTrackInsBefore Inserts a virtual track into the composition at the specified priority.
VTrackSwapPriorities Switches the priority levels of two tracks.


Header: Include Qedit.h. This header file is not compatible with Microsoft® Direct3D® headers later than version 7.

Library: Use strmiids.lib.