Active Sensing — A system used to verify that a MIDI connection is working. It involves the sending device sending frequent short messages to the receiving device to reassure it that all is well. If these active sensing messages stop for any reason, the receiving device will recognise a fault condition and switch off all notes. Not all MIDI devices support active sensing.
Aftertouch — A means of generating a control signal in a synthesizer based on how much pressure is applied to the keys of a MIDI keyboard. Most instruments that support this do not have independent pressure sensing for all keys, but rather detect the overall pressure by means of a sensing strip running beneath the keys. Aftertouch may be used to control such functions as vibrato depth, filter brightness, loudness and so on.
Bank — A specific configuration of sounds or other parameters stored in memory and accessed manually or via MIDI commands.
Breath Controller — A device that converts breath pressure into MIDI controller data.
Chase — A term describing the process whereby a slave device attempts to synchronise itself with a master device. In the context of a MIDI sequence, Chase may also involve chasing events — looking back to earlier positions in the song to see if there are any program change or other events that need to be acted upon.
Continuous Controller — Type of MIDI message used to translate continuous parameter changes, such as from a pedal, wheel or breath control device.
Dump — To transfer digital data from one device to another. A SysEx dump is a means of transmitting information about a particular instrument or module over MIDI, and may be used to store sound patches, parameter settings and so on.
Event — In MIDI terms, an event is a single unit of MIDI data, such as a note being turned on or off, a piece of controller information, a program change, and so on.
General MIDI — A universally agreed subset of the MIDI standard, created to enable manufacturers to build synthesizers, synth modules and plug-in instruments that exhibit an agreed minimum degree of compatibility.
GM Reset — A universal SysEx command which activates the General MIDI mode on a GM instrument. The same command also sets all controllers to their default values and switches off any notes still playing by means of an All Notes Off message.
GS — Roland's own extension to the General MIDI protocol.
LSB — Least Significant Byte. If a piece of data has to be conveyed as two bytes, one byte represents high value numbers and the other low value numbers, much in the same way as tens and units function in the decimal system. The high value, or most significant part of the message is called the Most Significant Byte or MSB.
Local On/Off — A function to allow the keyboard and sound generating section of a keyboard synthesizer to be used independently of each other.
MIDI (Musical Instrument Device Interface): MIDI is a standard language of control messages that provides for communication between any MIDI-compliant devices. Anything from synthesizers to lights to factory equipment can be controlled via MIDI.
MIDI Channels: MIDI allows for 16 discrete channels for sending data.
MIDI Clock: A MIDI device-specific timing reference. It is not absolute time like MIDI Time Code (MTC); instead, it is a tempo-dependent number of "ticks" per quarter note. MIDI clock is convenient for synchronizing devices that need to perform tempo changes mid-song.
MIDI Controllers: MIDI controllers are a specific type of MIDI message.
MIDI Notes: MIDI notes are a specific type of MIDI message. Any MIDI sequencer or controller will send MIDI notes.
MIDI Port: A MIDI port is the physical MIDI connection on a piece of MIDI hardware. This port can be a MIDI in, out or through. Your computer must have a MIDI-capable card to output MIDI time code to an external device or to receive MIDI time code from an external device.
MIDI Time Code (MTC): MTC is an addendum to the MIDI 1.0 specification and provides a way to specify absolute time for synchronizing MIDI-capable applications. MTC is essentially a MIDI representation of SMPTE time code.
Sample Dump: A sample dump is the process of transferring sample data between music equipment. Because of the large amounts of data required to store digital sound, sample dumps may take a very long time when using the MIDI Sample Dump Standard (SDS). However, when using the faster SCSI MIDI Device Interface (SMDI) protocol, sample dumps can be performed many times faster.
Sample Dump Standard (SDS): The MIDI Sample Dump Standard is a way to transfer samples between music equipment. Samples transferred with SDS are sent across MIDI cables at the MIDI data rate of 31,250 Hz baud. SMDI is a much faster sample transfer method for musicians.
Virtual MIDI Router (VMR): A software-only router for MIDI data between programs. No MIDI hardware or cables are required for a VMR, so routing can only be performed between programs running on the same PC.