Channel Messages; Example Keyboard Data - Yamaha Clavinova CVP-900 Owner's Manual

The "controller" and "tone generator" in the illustration
above are equivalent to the piano in our acoustic
example. Here, the player's performance on the keyboard
is captured as MIDI song data (see illustration below). In
order to record the audio performance on an acoustic
piano, special recording equipment is needed. However,
since the Clavinova features a built-in sequencer that lets
you record performance data, this recording equipment is
unnecessary. Instead, your digital instrument — the
Clavinova — allows you to both record and play back the
data.
Tone generator
Sequencer
Keyboard performance
(MIDI data)
However, we also need a sound source to produce the
audio, which eventually comes from your speakers. The
tone generator of the Clavinova fills this function. The
recorded performance is reproduced by the sequencer,
playing back the song data, using a tone generator
capable of accurately producing various instrument
sounds — including that of a piano. Looked at in another
way, the relation of the sequencer and the tone generator
is similar to that of the pianist and the piano — one plays
the other. Since digital instruments handle playback data
and the actual sounds independently, we can hear our
piano performance played by another instrument, such as
guitar or violin.
Even though it is a single musical instrument, the Clavinova can be
thought of as containing several electronic components: a control-
ler, a tone generator, and a sequencer.
Finally, we'll take a look at the actual data that gets
recorded and that serves as the basis for playing the
sounds. For example, let's say you play a "C" quarter note
using the grand piano sound on the CVP-900 keyboard.
Unlike an acoustic instrument that puts out a resonated
note, the electronic instrument puts out information from
the keyboard such as "with what voice," "with which
key," "about how strong," "when was it pressed" and
"when was it released." Then each piece of information is
changed into a number value and sent to the tone
generator. Using these numbers as a basis, the tone
generator plays the stored sampled note.
Using Your Clavinova with Other Devices

■ Example Keyboard Data

Voice number (with what voice)
Note number (with which key)
Note on (when was it pressed)
and
note off (when was it released)
Velocity (about how strong)
Panel operations on the CVP-900, such as playing the
keyboard and selecting voices, are processed and stored
as MIDI data. The auto accompaniment styles and songs
also consist of MIDI data.
MIDI is an acronym that stands for Musical Instrument
Digital Interface, which allows electronic musical
instruments to communicate with each other, by sending
and receiving compatible Note, Control Change, Program
Change and various other types of MIDI data, or
messages.
The CVP-900 can control a MIDI device by transmitting
note related data and various types of controller data.The
CVP-900 can be controlled by incoming MIDI messages
which automatically determine the tone generator mode,
select MIDI channels, voices and effects, change
parameter values and of course play the voices specified
for the various parts.
MIDI data has the following advantages over audio data:
• The amount of data is much less, letting you easily store MIDI
songs to floppy disk.
• The data can be effectively and easily edited, even to the point of
changing voices and transforming the data.
MIDI messages can be divided into two groups: Channel
messages and System messages.

■ Channel Messages

The CVP-900 is an electronic instrument that can handle
16 channels (or 32 channels, when using the TO HOST
terminal). This is usually expressed as "it can play 16
instruments at the same time." Channel messages transmit
information such as Note ON/OFF, Program Change, for
each of the 16 channels.
Message Name CVP-900 Operation/Panel Setting
Note ON/OFF Messages which are generated when the
keyboard is played. Each message includes
a specific note number which corresponds
to the key which is pressed, plus a velocity
value based on how hard the key is played.
Program Change Voice selecting (control change bank select
MSB/LSB setting)
Control Change Volume, panpot (Mixing Console), etc.
The performance data of all songs and styles is handled as MIDI
data.
01 (grand piano)
60 (C3)
Timing expressed numerically
(quarter note)
120 (strong)
CVP-900
157