Microsoft DirectX 9.0 SDK Update (Summer 2004)

^{Instruments and Downloading}

To play an instrument, the synthesizer needs information about how the instrument should sound. This information, consisting of waveform samples and articulation data, is stored in DLS collections. Instrument data is made available to the synthesizer by being downloaded.

By default, the Microsoft software synthesizer takes its DLS data from the Roland GM/GS collection. The default collection contains DLS data for the 128 instruments defined by the General MIDI standard. Custom collections can include instruments of any kind. The waveform samples for an instrument do not have to be based on a musical instrument but can be any recorded sound such as a sound effect, a fragment of speech, or even a fully formed measure of music.

Most applications do not need to access collections directly, as the necessary data is either contained in the default collection or referenced by a band object associated with a segment. A band is a set of instruments and settings mapped to performance channels. Several techniques are available for ensuring that band instruments are downloaded before use.

Note   The Roland GM/GS Sound Set cannot be modified, due to legal restrictions.

WAV files and resources also have to be downloaded to the synthesizer before they can be played.

A band is a collection of performance channel settings that determine how parts in a sound file are played. For each channel, a band includes an instrument assignment as well as settings for volume, pan, and transposition. Every part in a performance is mapped to a performance channel, and each part plays with the instrument settings applied to its channel by the band.

Although a band can be thought of as a set of instruments, it is not the same as a DLS collection. A DLS collection is a set of instruments that can be downloaded to the synthesizer and thus made available to any application. The instruments themselves contain no information about assignment to performance channels, volume, pan, or transposition. This data must be supplied by bands for the channels used by a performance.

Note   When bands are downloaded to the synthesizer, it is really the DLS instruments referenced by the band that are being downloaded.

Bands can be saved as separate files or included in styles or segments.

See Also

• Using Bands

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