A feature that enables a receiving MIDI device to implement an All Notes Off message should it ‘sense' an interrupted communication from a controller, thus preventing notes from ‘hanging' in the event of broken communication. A very useful feature for a MIDI device to implement.
A parameter that measures the level of intensity applied to a note ‘after' it has been played and continues to be depressed. After touch can be polyphonic (different notes will respond individually in a cluster of held notes) or per-channel (one value will apply to all notes held down on a particular MIDI channel). Typically, after-touch is useful for adding vibrato or tremolo effects to a sound in much the same way that a violin can add volume or pitch changes to a sustained note using finger vibrato or additional bowing intensity.
ALL NOTES OFF
A MIDI channel message that tells a MIDI sound-generating device to shut off all currently active notes. This is a life-saving device to cure ‘hanging' MIDI notes.
A collective storage location that houses multiple sounds, samples, patterns etc. In MIDI , an individual bank can hold up to 127 items. MIDI also allows for many different Banks to be selected using ‘Bank Select' commands.
A measurement of speed at which serial data is transmitted. MIDI operates at 31.25 kBaud, i.e. data can be transferred at a speed of 31250 bits per second.
A system of numbering using only the digits 0 and 1. This is the foundation of computer language and MIDI , too, uses a binary system.
BIT / BYTE
An abbreviation for 'binary digit,' a ‘bit' is the most basic unit of information used in any digital system, including MIDI . Generally there are 8 bits to a byte although MIDI adds additional two bits: one to signify start, the second, stop.
Big-Endian and Little-Endian derive from "Big End In" and "Little End In." These terms refer to the order in which a sequence of bytes is stored in memory. Big-Endian order means that the most significant byte (MSB) value is stored at the lowest address and each next most significant byte is stored in the next location and so on. Little-Endian is the reverse - the least significant byte (LSB) is stored at the lowest address and the other bytes follow in order of increased significance.
Bit depth is the number of bits (ones or zeroes in a binary number) that are used to describe digital data such as audio at a given point in time. One such point in time is a sample. Each added bit doubles the number of possible ways to describe each individual sample. A 16-bit sample can be described with any one of 65,536 values whereas a 24 bit sample has 16,777,216 possible values.
A MIDI Channel is a bus over which devices sending or receiving MIDI data can communicate. MIDI specifies that devices can specify or use up to 16 MIDI Channels (1-16) on any given port or network. In order to communicate, MIDI devices need to be set to the same MIDI Channel.
MIDI messages carrying a channel number in the header byte. Most day-to-day MIDI messages are Channel Messages, i.e. Note On, Note off, Program Change etc. Global MIDI data that is not channelised comes under the title of a System Message.
A regular series of electronic pulses that control the tempo of time-based devices (sequencers, drum machines etc). MIDI Clock—which substitutes pulses for MIDI clock messages—is a method by which two or more such devices can play in sync by choosing one device to transmit these messages and the other(s) to receive clock information externally (i.e. from the designated master device.)
A MIDI message tailored to parameters that require a range of multiple values such as modulation depth or volume. CCs can be controlled in real time by knobs, sliders, wheels, etc. or can be input as a series of parameter values into a MIDI sequence.
A MIDI controller is a device that transmits MIDI data. This can be as simple or as complex as required by the particular device and can range from keyboards (typically dedicated MIDI controller keyboards only control and do not generate sounds); to ‘alternate' MIDI controller instruments like MIDI guitars and wind instruments; to sensor-based devices such as knobs or sliders, or even gloves, pads, control surfaces etc.
The state of a setting when a device is purchased or powered-on. Also called "factory setting" or "initial setting." Most devices have a ‘reset' function whereby settings can be returned to their default state.
The original connection device used to send and receive MIDI data. MIDI used—and still can use—the 5-pin, 180-degree DIN connector, although only 3 of the pins are actually employed for MIDI communication.
A separate and specified MIDI message, be it a Note On or Note Off, pitch bend data, or a Program Change. Some devices (notably sequencers) may quantify their capacity in terms of ‘events' as opposed to notes, which can create misleading impressions since a single note might have several hundred MIDI events attached to it if after-touch, pitch bend, or modulation is employed extensively.
Though more commonly applied to audio, where actual volume or amplitude gradually increases and decreases, either MIDI Controller 7 (Volume) or 11 (Expression) messages can be used to create fade-ins/outs via a succession of parameter values that progressively increase or decrease from 0-127. If a fade-in/out is needed for an entire track comprising multiple MIDI Channels, the Controller messages will need to be applied to all channels being utilized.
In audio terms, a filter literally filters out certain frequencies in a signal or waveform in order to alter its tonal characteristics. Low, High, and Band pass filters let these frequencies pass through, filtering out the others. MIDI Continuous Controller messages (CC # 74 Brightness' and 71 ‘Resonance') can apply filtering to MIDI sound sources (commonly most GM sound sets) that respond to this parameter. A MIDI filter can also refer to a device that filters MIDI data as opposed to audio frequencies.
How data is organized in order that it can be recognized by particular applications or devices. Standardized file formats such as .WAV and .MID (Standard MIDI File) enable data to be transferred between applications made by different manufacturers so long as they share the same basic functionality (a MIDI sequencer, an audio engine etc.).
An older method of timing synchronization involving fluctuating pitch. Stands for Frequency Key Shifting. Though stable, and effective, it did make a particularly nasty ‘dentist's drill' type of noise.
GENERAL MIDI (GM)
A standard developed in the early 1990s based around sound types. It enables sequences (stored in .MID format) to be played back on any ‘GM' sound sources and sound at least ‘OK.' The establishment of a unified system of ‘Program Change' #s allows piano parts to call up piano patches, acoustic guitar parts, acoustic guitar patches, and so on. As with most things MIDI 128 basic sounds are specified, with provisions for additional sound subsets that can be offered on more sophisticated devices. Championed initially by Roland, whose Sound Canvas modules quickly became the de facto GM soundset, GM was for a long time the savior of both the game audio and cell phone industries where standardization was key. Though not as vital as it was in the 1990s, GM is still a useful tool for transferring song files, and the GM drum map (specifying which keys trigger which drum sounds) continues to be the norm on all but the most sophisticated synthesizer drum voices.
A system of numbering based on 16 (as opposed to 10 on regular decimal systems). In addition to 0-9 the letters A-F are employed. MIDI codes are most commonly supplied in this format.
The place where a keyboard is set up to trigger two or more different voices across its range.
MIDI Channel Message that sets whether your keyboard is going to trigger its internal sounds (Local ON) or not (Local OFF). This is a vital parameter to have control over in order to avoid loops and double-triggers when your keyboard is part of a larger, computer-involving rig of equipment.
As it sounds, where music or data repeats endlessly. Sometimes this is a good thing, as in a drum loop or a musical refrain. A loop point in a sample is where the end meets the beginning again (and which you want to be as seamless as possible). A loop can be undesirable where data feeds back on itself as in ‘feedback' with audio. Unlike audio, which can indeed be desirable, a data loop will generally cause a device or program to wig out and probably crash. If you have such control at hand, a MIDI Reset command can provide a cure.
(LEAST SIGNIFICANT BYTE) LSB
This refers to the byte of least potential value in a multibyte number such as a number sent as MIDI control data.
A sound card MIDI adapter cable lets you connect MIDI devices to your computer via the computer's joystick port.
Standard cable used to connect MIDI devices featuring 5-pin DIN connectors on both ends. MIDI can also be transmitted by other means (cables): USB, FireWire, and indeed wireless.
MIDI data is communicated using a system of 16 discrete 'Channels,' each of which can be used to send and receive specific commands between connected devices. When making connections between instruments/computers/devices, you normally will choose a MIDI Channel (between 1-16) on which you want to communicate. On DAWs, you will frequently want to utilize several MIDI Channels; one for each track of a song. You may also need to utilize several MIDI ports; each of which can communicate using their own 16-channel system.
When too much MIDI data is being transmitted or received simultaneously. Results of this can vary; from impaired timing, to failure of all notes to trigger, to system lock-up. The cause can simply be too much data on the move, or be caused by incorrect connections or settings causing a MIDI data loop. A cure may be found by sending Reset or All Notes Off messages, or your set-up may require re-patching / re-cabling.
Any electronic device that can generate and send MIDI data. Most commonly seen are MIDI keyboards, but there are many others: MIDI guitars, MIDI drum pads, MIDI wind controllers, boxes of knobs, gloves, and more. All non-keyboard controllers are often referred to as ‘alternate' MIDI controllers.
Catch-all term for any and all information being communicated between MIDI devices.
Generic term for any MIDI-enabled piece of hardware or software from a synth to a sound module, interface, controller etc.
Abbreviation of ‘Standard MIDI File' (SMF): sequencer files that adhere to the protocols of SMF format. Most DAW/sequencer applications can, in addition to generating their own proprietary file formats, save and load sequences in this easy-to-transfer format. Though not compulsory, most MIDI Files will also use the GM system of note-mapping (for drums) and sound assignments in order that they can be played back on a wide range of systems and soundsets.
MIDI IN, OUT, THRU
Names and functions of the MIDI ports found on most MIDI devices. MIDI IN will accept incoming data only. MIDI OUT will transmit data. MIDI THRU passes on data that is being received at the IN port to another device.
The point or points at which MIDI data can be connected to a device. Most computers do not sport MIDI as standard, and therefore will require some type of (additional) MIDI interface in order to handle MIDI data.
An electronic keyboard that possesses the ability to send and receive MIDI data. Micro switches beneath the keys connect to a MIDI processor where such information as note, duration, and velocity (key speed/strength) can be processed.
The point or points on a MIDI device where you connect to other MIDI devices. Initially, 5-pin DIN connectors were used exclusively. A MIDI port could also be USB/FireWire nowadays.
Most commonly, software (though in the past hardware too) applications or devices used for the assembly of musical compositions. A musical word-processor, if you like. The word ‘sequencer' is now not used so often as Digital Audio Workstation, a somewhat grander sounding name for sequencers that now also possess the ability to handle audio and a myriad other processing tasks.
Real-time System message that drives and can synchronize performance data in and between MIDI devices. MIDI Clock operates at 24 ppqn (pulses per quarter note) or ‘divisions' per beat.
A device that accepts MIDI data from various sources and merges it into a single (output) source.
Packets of data that form a MIDI transmission.
MIDI TIME CODE (MTC)
System comprising the information contained in a SMPTE signal in MIDI form that can be recognized by MIDI devices. Not all MIDI devices may implement MTC, however.
MIDI MACHINE CONTROL (MMC)
Group of MIDI messages used to control recorder operations such as Play, Stop, and Record.
Wheel controller found on synthesizers that players can use to progressively introduce modulation depth to a sound. The mod wheel itself can normally be assigned to many different parameters selected by the user, though it is most commonly applied to pitch in order to produce vibrato.
A word that has a great many definitions, but in a purely MIDI context it signifies that only one note per channel is possible. MIDI Modes 2 & 4 assign mono one voice unilaterally and one voice per multi-timbral MIDI channel, respectively.
MSB (MOST SIGNIFICANT BYTE)
This refers to the byte of highest potential value in a multibyte number such as a number sent as MIDI control data.
The capacity of being able to generate multiple (and different) voices simultaneously, each controlled on its own MIDI Channel.
NOTE ON/OFF COMMAND
Messages indicating when notes begin and end. A Note Off message doesn't always make the sound of the note stop immediately - the envelope might well mean that the sound fades away gradually. When you're editing a MIDI event list using some sophisticated tool (Notepad, for example) don't forget to make sure that each Note On message has a matching Note Off message. Don't forget that you sometimes see Note On messages with a Velocity of 0 used instead of Note Off messages. Don't do that though, it's naff.
A word (latin for ‘all') used as a descriptor for some of the ‘modes' that MIDI devices can choose to operate in. Omni ON signifies a device will respond on all MIDI channels. In Omni OFF (poly – Mode 3) a device only responds to a single, predetermined MIDI channel, and in Omni OFF (mono – Mode 4) each voice can be assigned to its own MIDI channel.
A throwback to the days of modular synthesizers when different modules and parameters within them could be connected using (physical) patch cords. The final sound that resulted from frequently multiple patching, eventually came to known as a ‘patch.' Fast forward to modern synthesizers and the word is now used to describe any single and identifyable ‘sound' as in a brass ‘patch', a piano ‘patch' etc.
A wheel type device, normally found to the left of a synthesizer keyboard, used to manipulate the pitch of a played note or notes.
A Channel Voice Message or activity or message, generally initiated by a pitch wheel (though any other controller set to manipulate pitch will do), that smoothly raises and/or lowers the pitch of note or chord. This can be achieve in real time during a performance, or can be recorded into a sequence. Unlike data for volume, or note #, pitch bend uses a complex string of data, making it difficult to ‘edit.'
Short for polyphonic. The state of being polyphonic indicates a musical device's capacity of playing multiple notes at a time.
A connection point. ==TDM plug-ins for ProTools were the first to appear, though soon after Steinberg developed the universally adopted VST standard. Other plug-in standards include DirectX and RTAS.
A patch or program on a device that cannot be overwritten.
A Channel message (from 00-127) that tells a device to switch to a particular patch/voice/preset etc. A Program Change message can – indeed should - be accompanied by a Bank Select message since MIDI can specify many different banks of 128 programs. Without adding a Bank Select command, a receiving device will simply move the Program Change # indicated within its currently selected bank. It is essential that Program Change messages are placed at the beginning of GM sequences (MIDI Files) in order that piano parts will be played back on piano sounds, guitar parts on guitar sounds etc.
Within a MIDI sequence, the automatic adjustment of timing values to some formula or pattern other than the one originally recorded. At its most basic level, to quantize a passage to sixteenth notes will drag all notes to their nearest sixteenth note, so making the passage sound both very in-time, but also very stiff and mechanical. There are many more subtle settings and styles that can both ‘correct' timings, in a more natural manner, and even create human feel ‘groove quantizing' where none originally existed. In digital audio, the term indicates the resolution of a recorded signal, as in 16-bit or 24-bit quantization.
As it sounds, an action or process that is executed live, as it happens. Real-time recording on a sequencer or DAW records actual performances as opposed to ‘step-time' recording where data is input piecemeal. Real-time controllers provide instant ‘live' control over some aspect of a sound or performance.
A form of communication that transmits information sequentially, i.e. one piece of information (bit) after another. MIDI uses this form of communication. The opposite is a Parallel system, whereby data is transmitted simultaneously.
A musical word processor: a software application, or feature found on a hardware keyboard workstation, that can record, process, and play back MIDI events designed to be trigger sound-generating devices or software for the purposed of recording complete pieces of music. Though sequencing began life as a MIDI-only entity sequencers eventually embraced audio recording as well. Modern software devices that can record, process and play back both MIDI and audio are now generally referred to a Digital Audio Workstations or DAWs (pronounced ‘doors').
The speed at which a song or loop plays. Tempo can be set, and can be programmed to vary over the duration of a song in order to create a more natural human feel, using MIDI Clock.
The smallest increment of a beat; based upon the resolution of the device or application being used.
Time data used to synchronize devices.
The MIDI THRU port passes ‘through' to the MIDI OUT port data that is being received at the MIDI IN port. ‘Soft' THRUs are OUTs that can be configured as a THRU whenever necessary.
For units that don't have a THRU port you can purchase one of these physical boxes. Generally they will provide a MIDI IN socket and several THRU output ports.
Where MIDI is being delivered via a USB interface.
Measurement of the speed – and so in practice the intensity and volume, that notes are being played at. MIDI has velocity levels from 0 to 127.
A synchronization signal used when transferring digital audio data; used to ensure that the audio data is received at the same rate it is being transmitted. When multiple devices are digitally connected, all need to use the same word clock to avoid problems of audio transfer and, most likely, unwanted noise in the signal.