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Advanced Manual - Viscount
Prestige
6.3 MIDI FUNCTIONS
WHAT MIDI IS
The MIDI (Musical Instrument Digital Interface) interface allows instruments of different makes and kinds to
communicate with each other, using this very specific protocol of codes. This allows the creation of systems of MIDI
instruments, offering much greater versatility and control than is possible with single instruments. To make this
communication possible, all MIDI instruments have two or three 5-pin DIN connectors called:
-
MIDI IN:
The connector through which the instrument receives the MIDI data transmitted by other units.
-
MIDI OUT:
The connector through which the instrument sends the MIDI data it has generated to other units.
-
MIDI THRU:
This connector, not always provided on all instruments, is used for connecting several units in
series, since it transmits the MIDI data exactly as they are received by the respective MIDI IN port.
Most instruments equipped with MIDI interface transmit MIDI messages which specify, for example, which note has
been played and with what dynamic, by means of the MIDI OUT connector. If this connector is connected to the MIDI
IN connector of another MIDI instrument, such as an expander, the second instrument will respond exactly to the notes
played on the transmitter instrument.
The same type of information transfer is used for recording MIDI sequences. A computer or a sequencer can be used to
record the MIDI data generated by the transmitter instrument. If these recorded data are sent back to the instrument, it
automatically repeats the recorded performance.
MIDI is able to transmit a multitude of digital data by means of just one cable, and thus just one connector. this is
thanks to the MIDI channels. There are 16 MIDI channels, and in a similar way as for radio communications in which
two stations can only communicate if they are tuned to the same frequency (or channel), two MIDI instruments connected
together are only able to communicate if the transmitter instrument channel is the same as the receiver instrument
channel.
MIDI messages subdivide into channel messages and system messages. The following is a short description of these
messages:
CHANNEL MESSAGES
NOTE ON
This message is transmitted when a note is pressed on the keyboard. Each Note On message contains the following
information:
Note On
: when a key has been struck;
Note Number
: the key which has been pressed, and therefore the relative note played;
Velocity
: note dynamic (i.e. the force applied when the key was struck).
Note messages are expressed as a number from 0 to 127, with middle C represented by number 60.
NOTE OFF
This message is transmitted when a key struck previously is released.
When it is received, the sound of the note relating to the key is switched off. Each Note On message contains the
following information:
Note Off
: a key has been released;
Note Number
: which key has been released;
Velocity
: dynamic (i.e. how fast the note was released).
N.B.:
A Note On message with Velocity=0 is considered equivalent to a Note Off message. The Prestige sends the Note On
message with Velocity=0.
PROGRAM CHANGE
This message is used to select the programs or sounds of the receiver instrument.
There is also a specific standard called General MIDI which describes which sound should be recalled for each Program
Change received. This association is usually described by means of a table included in the user manual of the instrument
which adopts the standard.
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