MIDI and YOU Orchestra in a Box What

MIDI and YOU Orchestra in a Box

What is MIDI? § Musical Instrument Digital Interface § MIDI is a protocol - a standard by which two electronic instruments (as well as other things) can communicate § MIDI defines both a physical (wires, plugs and voltages) and a logical (how the information is organized) component. § MIDI only contains the instructions necessary to “reconstruct” a song. (e. g. sheet music for electronic instruments)

MIDI Specs § First defined in 1983 - not much has changed § 31. 25 kbaud - serial communication § Allows for 16 separate channels of information on a single cable (i. e. it can send information for up to 16 different “instruments” simultaneously) § Any parameter can have up to 128 different values

Common MIDI terminology § A MIDI Controller: generates MIDI messages to trigger other devices § A Sound module has a number of pre-recorded instrument sounds (called patches) stored in its memory. § MIDI messages trigger MIDI events – i. e. tell the sound module which note to play § A MIDI Sequencer stores MIDI messages and events in the order in which they happen. These messages can then be played back – a sequencer is a multi-track recorder for MIDI instruments. § DAW – Digital Audio Workstation – a program that allows you to sequence MIDI and record audio on your computer

Anatomy of a MIDI message § There are different types of messages that can do different things § MIDI channel voice messages contain the channel number the message is intended for (1 thru 16), a command (e. g. note on), and velocity information (how hard a key is played). § A typical command is a text message that basically contains note-number, note-velocity, and note-on messages - THAT’S ALL! ex: <channel 1><note 64><velocity 85><note on>

Benefits of MIDI § File sizes are extremely small, so a large amount of information takes up a very small amount of space, bandwidth, and processing power § MIDI is not limited to musical applications § Flexibility: § You can use whatever instrument sounds you wish – you are not limited to the ones you are physically able to play § You can change instrument sounds any time you wish. MIDI does not care what type of instrument is receiving the message (i. e. what it is triggering). § You can easily change or edit a performance – timing, note duration, pitches – everything can be changed easily

Downsides of MIDI § It’s not a real instrument § Patches are not always standard – you might not have the same sound set as another person § “only” 128 possible values for any parameter § for volume and panning, this can be annoying § MIDI productions can sound “fake” – both in terms of sound and performance § Occasionally “buggy” § Slow, old, and limited for some things

General MIDI § General MIDI was an attempt to standardize MIDI instruments so that it would be easier to use for long distance collaborations, computer music, and web-based applications. § General MIDI devices have specific instruments assigned to specific numbers so that a device or computer playing back a MIDI file will use the proper instrumentation. § Channel 10 is reserved for drums § Not all MIDI devices are meant to be General MIDI compatible

A little music theory…

Pitch § Pitch is the “perceived fundamental frequency of a sound” – the “high-ness” or “low-ness” in tone (not volume) of a given note. § There are 7 primary pitches which are given letter names A through G; § On the 8 th pitch, the pattern is repeated, giving us the octave. § Western music recognizes 12 distinct pitches per octave

Octave and note numbers § MIDI has 128 notes. On a typical Grand Piano patch, middle C is note 60 § Some programs number the octaves (e. g. -1, through 9 § The octaves are numbered from lowest to highest, with C being the start of the octave. § Each note is named with its letter and octave (e. g. C 4, E 4, G 4) § MIDI note numbers are standard; Octave numbers are NOT § this can be confusing. (e. g. Middle C could be called C 3 or C 4 depending on which program you use, but it is still MIDI note 60)

Rhythm & Tempo § Time is divided in bars or measures § Each bar is defined as having a specific number of beats § Each beat is defined as the length of a specific note (e. g. quarter-note or eighth note) § This is called meter or time signature; most pop songs are in 4 -quarter (4/4) time § Tempo = how fast the beats are going § The same song can be played at different “speeds”

Quantizing § MIDI uses a “grid” that is defined by note values § Ie. A quarter-note grid or eighth-note grid § Notes can be “snapped to the grid” to correct irregularities (i. e. sloppy mistakes) in the rhythm § This is known as “Quantizing” or “Quantization” § If done “incorrectly, ” quantization can sound robotic

Working with MIDI in the box

MIDI Signal Chain § MIDI flows in one direction § MIDI devices have three ports: IN, OUT, and THRU – § MIDI OUT sends MIDI messages that a device generates, § MIDI IN receives the MIDI messages, § MIDI THRU simply copies any messages that appear at the MIDI IN port and passes them down the chain. § Up to three MIDI devices can be “daisy-chained” without any noticeable latency in the chain § YOU STILL NEED TO WORRY ABOUT AUDIO SIGNAL FLOW! MIDI does NOT carry audio signals

Types of tracks You need two things when working with MIDI in a computer: § You must be able to hear the device. An Aux Input track might be necessary; § You must be able to record and playback MIDI messages. A MIDI Track might be necessary; § Most programs combine these two tracks into one for use with virtual instruments. Pro Tools has an Instrument Track for this purpose.

Virtual Instruments aka: software synthesizers or “soft synths” § Virtual - “existing…in effect though not in actual fact” Webster’s II New Riverside Dictionary § A virtual instrument exists as a plug-in in a DAW § Plug-in: “A computer program…that interacts with another [program] to add a specific function…” - en. wiktionary. org/wiki/plug-in § A virtual instrument is basically a MIDI instrument that exists in software instead of the real world § It needs all the same things that an external MIDI instrument (such as a sound module) would need (except cables).

Things to consider § Use a click track or metronome from the very start § Set your tempo and meter correctly § Use quantization (judiciously) before you overdub new instruments § You can easily change your tempo any time you wish later on, but something that is not in time will not work at ANY tempo THESE THINGS WILL SAVE YOU TIME AND FRUSTRATION LATER

MUY IMPORTANTE § MIDI does not generate or transmit any sound or audio signal whatsoever § You cannot hear MIDI § MIDI is only a protocol - a language which computers and electronic instruments use to communicate. Humans cannot hear MIDI. § You can only hear the result of a properly routed MIDI message, provided it is sent to a device capable of making sound § MIDI is NOT digital audio in any way, shape, or form