The Midi Kit: The Midi Kit

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# The Midi Kit

The Musical Instrument Digital Interface (MIDI) is a standard for representing and communicating musical data. Its fundamental notion is that instantaneous musical events generated by a digital musical device can be encapsulated as "messages" of a known length and format. These messages can then be transmitted to other computer devices where they're acted on in some manner.

The Midi Kit understands the MIDI software format (including Standard MIDI Files). With the Kit, you can create a network of objects that generate and broadcast MIDI messages. Applications built with the Midi Kit can read MIDI data that's brought into the computer through a MIDI port, process the data, write it to a file, and send it back out through the same port. The Kit also contains a General MIDI synthesizer that you can use to realize your MIDI scores. This is a software synthesizer that includes reverberation—you don't any outboard equipment to use it.

The documentation of the Midi Kit is divided into two parts: The first part describes the basic MIDI classes; the second part describes the classes that give you access to the Headspace synthesizer. There are four basic MIDI classes:

- The BMidi class is the centerpiece of the Kit. It defines the tenets to which all MIDI-processing objects adhere, and provides much of the machinery that realizes these ideas. BMidi is abstract—you never create direct instances of the class. Instead, you construct and connect instances of the other Kit classes, all of which derive from BMidi. You can also create your own classes that derive from BMidi.

- BMidiPort knows how to read MIDI data from and write it to a MIDI hardware port.

- BMidiStore provides a means for storing MIDI data, and for reading, writing, and performing Standard MIDI Files.

- BMidiText is a debugging aid that translates MIDI messages into text and prints them to standard output. You should only need this class while you're designing and fine-tuning your application.

The synthesizer classes are:

- BSynth represents the General MIDI synthesizer and controls some of its global settings (reverb, volume, and so on). Every app that wants to use the synthesizer must have a single BSynth object (represented by the global `be_synth` variable). The other synthesis classes (below) create this object for you.

- BMidiSynth is a BMidi-derived class that connects the basic MIDI world (as represented by the BMidi class) to the synthesizer.

- BMidiSynthFile is a subclass of BMidiSynth that lets you play a MIDI file on the synthesizer.

- BSamples is an interface to the synthesizer's sound data stream. It lets you mix normal audio data in with the synthesized sound.

## The MIDI Specification

This documentation doesn't attempt to teach you anything about the MIDI or General MIDI specifications. In many cases, you don't need to know anything about the specs (or at least not much). For copies of the MIDI specs, search the Web for "midi specification" (there are dozens of copies out there); or go to the official source at http://www.midi.org.

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