The PlayPrimary sample shows how to play a primary segment based on an authored music section.
Source: (SDK root)\Samples\Multimedia\Dmusic\Src\PlayPri
Executable: (SDK root)\Samples\Multimedia\DMusic\Bin
Click Close to quit the program.
The program uses the registry key set up by the DirectX SDK setup to find the media file path.
Helper.cpp contains useful functions that set up DirectMusic. These functions are called from Main.cpp.