Midi; What Is Midi - Physis Piano H1 Reference Manual

Manuale di Riferimento – MIDI

7. MIDI

7.1 WHAT IS MIDI

MIDI interface (Musical Instrument Digital Interface) allows instruments of different kind and brand to communicate through
a common protocol. MIDI instruments can create systems, making them much more efficient and versatile than single
isolated instruments. This communication takes place through DIN 5 poles connectors, called:
- MIDI IN: the MIDI input, that receives data from other instruments.
- MIDI OUT: the MIDI output, that sends out generated data to other devices.
- MIDI THRU: this port can link several instruments in order to create a chain. It sends out MIDI data as it comes in from
the MIDI IN port. Not all instruments have a MIDI THRU port.
Instruments equipped with a MIDI interface can send MIDI messages to the MIDI OUT port. These messages contain
information on which note has been played and its dynamic. If the MIDI OUT port is connected to the MIDI IN of another
instrument, such as an expander set, the latter will act according on the notes received by the first instrument.
MIDI messages can also be used to record MIDI tracks. A computer or a sequencer can record the MIDI data generated
by an instrument. Then the data can be sent back to the instrument, that will play again the recorded performance.
Large amounts of data can be sent through one single MIDI cable at the same time. This is possible thanks to MIDI
channels. There are 16 MIDI channels available. They work like radio channels: two stations can only communicate if they
are using the same frequency (or channel). In the same way, two MIDI instruments can only exchange data if both share
the same channel.
MIDI messages can be either channel messages or system messages. Both are described below:
CHANNEL MESSAGES
NOTE ON
This message is transmitted when a keyboard note is pressed. Each Note On contains the following data:
Note On
: when the key has been pressed;
Note Number
: which key and therefore note has been pressed;
Velocity
: dynamic, that is, the quantity of pressure on the key.
Note numbers vary between 0 and 127; the central C corresponds to number 60.
NOTE OFF
This message is transmitted when a key is released. When the message is received, the corresponding sound stops.
A Note Off message contains the following data:
Note Off : a key has been released;
Note Number : which key has been released;
Velocity
: dynamic, that is, energy of the release.
NB: if a Note On message has Velocity=0, it counts as a Note Off message.
PROGRAM CHANGE
This message selects sounds or programs on the receiving instrument.
The sounds recalled by each Program Change message is described by the General MIDI standard. Usually, the recalled
sounds can be found on a chart included in the User Manual of instruments using this standard.
This message contains the following data:
Program Change : change sound or program;
Program Change Number
CONTROL CHANGE
These control messages are often associated to potentiometers or pedals, and are useful to add expressivity to a
performance. Control change message can describe or control in real time expression parameters such as volume (CC
n.7) or expression pedal position (CC n.11), Sustain (CC. N.64) etc...
This message contains the following data:
Control Change: a control has been changed
Controller Number: which control has been modified (number)
Controller Position:
the controller position
: the number of sound/program that has to be activated;
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