Microsoft DirectX 8.1 (C++)

Using Segments

Segments are the basic units of playable data in the DirectMusic performance. A segment is represented by an IDirectMusicSegment8 interface.

You can create a segment object in an application by any of the following means:

Load a file or resource object that supports the IDirectMusicSegment8 interface. For more information, see Loading Audio Data.
Get a motif from a style by using the IDirectMusicStyle8::GetMotif method.
Use methods of the IDirectMusicComposer8 interface to create a composition or transition at run time. See Overview of Programming for Composition and Using Transitions.
Make a copy of an existing segment by using the IDirectMusicSegment8::Clone method.
Use the IDirectMusicBand8::CreateSegment method. This creates a special type of secondary segment that is used only for making band changes. See Making Band Changes Programmatically.
Use the IDirectMusicPatternTrack8::CreateSegment method to create a segment from a pattern track object. Most applications don't do this, because pattern track objects usually come from segments in the first place.
Construct a segment from existing tracks. Create a segment object by calling CoCreateInstance, and then add tracks by calling IDirectMusicSegment8::InsertTrack. This technique is not used by most applications.

Each segment consists of one or more tracks, each represented by an IDirectMusicTrack8 interface. Tracks contain most of the data for the segment, whether that data consists of note events, band changes, tempo changes, or other timed events. Applications generally don't need to use this interface, because the tracks are managed through the segment object. For more information, see DirectMusic Tracks.

Segments can perform different roles in the performance. There must always be a primary segment, which provides the main content of the soundtrack and normally serves as the control segment. Secondary segments play along with the primary segment and might provide sound effects or short musical themes. A special type of secondary segment is the motif, which is always obtained from a DirectMusic style object.

In addition there are three kinds of segments with special roles:

Transition segment. A short musical transition created at run time by the DirectMusic composer object and normally played as a primary segment leading from one segment to another, or from a segment to silence.
Band segment. A set of instruments and instrument settings for the various channels in the performance. The application can play a band segment as a secondary segment to execute changes in the band performing the music.
Template segment. A guide to chord progressions, groove levels, and embellishments, used in conjunction with a style and chordmap to compose music at run time.

The playback of segments is controlled by the performance object and begins with a call to IDirectMusicPerformance8::PlaySegment or IDirectMusicPerformance8::PlaySegmentEx.

Only one primary segment can play inside a performance. When you cue a primary segment for playback, you can specify that it is to be played after the currently playing segment is finished, or you can use it to replace the current primary segment.

Secondary segments, on the other hand, play over the current primary segment, and any number of secondary segments can be playing simultaneously.

Secondary segments do not normally alter the performance of the primary segment. For example, a secondary segment can be based on a different style without affecting the style of the primary segment. However, a secondary segment can be designated as the control segment, in which case it takes over certain tasks normally handled by the primary segment.

More information on segments is contained in the following topics: