Java Examples in a Nutshell, 3rd Edition

Synthesizing a MIDI Sequence

MIDI audio is quite different from sampled audio. Instead of recording samples of an actual audio waveform, MIDI files record a sequence of keystrokes on a real or virtual synthesizer keyboard. MIDI can’t be used to represent voice data, but it is a versatile and compact format for polyphonic electronic music. Many hobbyists transcribe well-known works to MIDI or publish their own compositions as MIDI files. An Internet search will reveal many MIDI samples that you can play with any of the audio player programs we’ve developed previously in this chapter.

The javax.sound.midi package is useful not only for playback of predefined MIDI files but also for synthesis or playback of MIDI Sequence objects. The program in Example 17-5, PlayerPiano, takes as input a musical score (defined using a simple grammar) and creates a Sequence of MidiEvent objects. It then either plays that Sequence through a Sequencer object or saves the Sequence as a MIDI file for playback with some other sound program.

Invoke PlayerPiano with the score as a single quoted argument. You can use the -o argument to specify a filename to save the MIDI file to. Without this argument, the score will be played instead. Use -i to specify a MIDI instrument number between 0 and 127. Use -t to specify the tempo in beats (quarter notes) per minute. The notes to play are indicated using the letters A through G, with b and # for flat and sharp, respectively, and “.” for rests. Notes separated by spaces ...