The information in this topic pertains only to applications written in Visual Basic. For C++ applications, see Overview of DirectMusic Objects and Interfaces.

Much of the music played in DirectMusic applications is fully authored either as a MIDI file or as a segment. However, DirectMusic also allows applications to compose music at run time, based on elements such as styles and templates.

The DirectMusicComposer class has methods that create DirectMusicSegment objects representing either templates, playable segments based on a chord map or template, or transitions based on other segments. The composer object can also be used to change the chord map of an existing segment.

The DirectMusicChordMap class represents a chord map loaded from a file or resource, which provides DirectMusicComposer with the information that it needs to compose chord progressions.

An object of the DirectMusicStyle class is also based on data from a file or resource, either as a separate entity or as part of an authored segment. It represents a set of musical patterns used in composition and can be passed to methods of DirectMusicComposer. Its own methods can be used to retrieve other elements that might have been determined in the style, such as motifs and bands.