added InstrumentStream (Stream:instrument)

 * allows a stream of note velocities to trigger a note-on and note-off stream.
 * usually used on a MIDIVelocityStream
 * allows a single note to be triggered including attack, sustain and decay
   phases
 * by letting the note-on and note-off streams depend on the note/velocity stream,
   the note can use the NOTE ON velocity.
 * The InstrumentStream constructor will also accept functions on the note_stream,
   so it is possible to define the note-on/off streams depending on the velocity stream
   on a single line of source code.
 * A NOTE OFF velocity is currently not used, though that could be achieved by
   letting MIDIVelocityStream generate negative numbers for NOTE OFF velocities.
 * This will only work with a single note (ie. a fixed frequency);
   when wanting to play polyphony, users will have to mix many different InstrumentStreams, e.g.
   iota(69, 79):map(function(note)
     return MIDIVelocityStream(note, 1):instrument(function(v) return InstOn(note, v) end,
                                                   InstOff(note))
   end):fold(function(x,y) return x+y end):ravel()

0 files changed, 0 insertions, 0 deletions