DirectMusic For The Masses

DirectMusic For The Masses

Introduction History DirectMusic's Innards Segments, Tracks and Tools Programming The DMS Loader Output API Basic Playback Layers Composing With Producer How Deep Do You Want To Go Today? The Future

Output API: Instruments and Ports

The basic means by which DirectMusic makes actual sounds come out of the digital-to-analog converters of a game player's PC is DLS. The API represents DLS instruments with the DirectMusicInstrument object, and sets of instruments (Collections and Bands) with the DirectMusicCollection and DirectMusicBand objects. The way any of this gets out of the box is via a Port object.

To use DLS in an application, first you must have one or more files full of DLS instruments, comprising both sample data and associated control (articulation) data. This industry-standard (not just Microsoft's) file type is known as a DLS Collection. As a simple enhancement to General MIDI, you can use the General MIDI/GS DLS collection bundled with DirectMusic. This way, all of your users will hear the same sounds, and you won't play sound-card roulette.

Of course, using the stock GS set sort of misses the point of using custom sounds. The better way is to have your crack team of composers and sound designers deliver custom DLS collections comprising instruments specifically developed to go along with your game's music. Sound designers can also supply DirectMusic bands, which are detailed references to DLS data in one or more collections (Figure 4).

Figure 4: DLS Device: Band/ Instrument Relationships