MIDI in music production: understanding the digital protocol powering professional and home studios.
Before jumping into music production, it's extremely important to learn some basics first. In my experience, understanding MIDI is often the first challenge for people new to this, especially musicians who are used to playing physical instruments and may not be tech-savvy. The idea that MIDI is just digital data representing a musical composition, without containing actual sounds, can be confusing at first. This article is about what MIDI is and how it technically works. Grasping concepts like MIDI, digital music, and how it gets converted into analog waveforms may sound boring, but it's crucial knowledge for music producers. It allows you to better understand the digital music processes within your digital audio workstation (DAW). Having a handle on some MIDI theory goes a long way in demystifying your DAW and setting you up for success in music production. It may feel tedious at first, but stick with it! Once you've got the basics down, it gets much smoother.
The following diagram illustrates the different types of signal interaction between devices
What is MIDI?
MIDI is a language that simply conveys information about which note was played, the intensity of the keypress, and the duration of the note. It is not audio, computers can read this MIDI language and convert it into sound using their built-in sound libraries.
MIDI (Musical Instrument Digital Interface) is a technical standard that allows electronic musical instruments, computers, and other equipment to connect with each other and exchange musical performance data. The MIDI protocol transmits event messages that specify notation, pitch, velocity, vibrato, panning, cues, and clock signals. This allows sequencing, automation, and remote performance control of musical instruments from a computer or other device.
The key elements of MIDI data include:
- Note On/Off Messages – Triggers a note to start or stop. Includes pitch and velocity.
- Control Change Messages – Alters parameters like volume, panning, vibrato, and sustain.
- Program Change Messages – Selects instrument sound patches.
- Pitch Bend Messages – Bends note pitch up and down.
- System Exclusive Messages – Allows custom controller data.
- System Messages – Tempo, time signature, song position, etc.
Because MIDI files contain no actual audio data, they are very small in file size. This allows MIDI sequences to be transferred between devices nearly instantly. The performance information can then be interpreted into audio on the receiving end. This is what makes MIDI so versatile for music production and performance applications.
How MIDI Works
MIDI messages communicate musical performance data between devices. For example, when you play a key on a MIDI keyboard, it sends a MIDI note-on message with a pitch value that corresponds to that key. This pitch value is encoded numerically between 0-127, where 60 represents middle C. The velocity, or how hard the key was struck, is also encoded from 1 (soft) to 127 (hard). When the key is released, a note-off message is sent. These messages allow MIDI devices to exchange musical performance information in a standardized way.
Messages are sent over 16 MIDI channels, which allows connecting multiple instruments and separating their signals. For example, channel 1 could be assigned to a bass sound, channel 2 to drums, etc. MIDI channels allow each device to receive only the messages relevant to generating its sound.
In addition to note on/off messages, MIDI can transmit controller data like sustain pedal, modulation wheel, and pitch bend values. This continuous controller data allows more expressive performances. MIDI can also synchronize tempo via clock messages, which is vital for lining up sequenced parts between instruments.
MIDI messages are sent at a high rate to capture the nuances of a performance. At a 10 ms interval, this produces 100 messages per second. MIDI data has a very small bandwidth of only 31.25 kbps. This allows MIDI to be transmitted over simple cables up to 15 meters long. Opto-isolators keep MIDI devices electrically separated, avoiding ground loops while maintaining fast transmission speeds.
While MIDI transmits performance data, it does not transmit an audio signal. The receiving instrument is responsible for generating audio based on the MIDI messages using oscillators, samplers, or other sound sources. This is a key distinction between MIDI and digital audio.
How Is MIDI Used in Music Production?
In a typical home studio setup, a MIDI controller like a keyboard is connected to a computer running a digital audio workstation (DAW) like Ableton Live, Logic Pro, Pro Tools, or FL Studio.
Within the DAW software, the MIDI data generated from the controller can be routed to trigger sounds from virtual instrument plugins like synthesizers, samplers, and drum machines.
Here are some of the most common ways MIDI is leveraged in modern music production:
- Playing software instruments like piano VSTs, synth VSTs, and drum VSTs using MIDI controllers.
- Drawing in MIDI note patterns with your mouse to program melodies, baselines, and drum beats.
- Importing MIDI loops and phrases to quickly add musical elements like arpeggios, fills, etc.
- Editing MIDI note pitch, length, velocity, and other parameters from recorded performances.
- Using MIDI effects plugins like arpeggiators, chord generators, etc.
- Automating parameters like volume, panning, and filter cutoff for dynamic sound design.
- Synchronizing equipment like drum machines and hardware synths via MIDI clock.
The power of MIDI in production is that it can be used to compose, manipulate, and perform musical parts in extremely flexible ways. MIDI data functions as a universal language between music devices and software.
Types of MIDI Controller Hardware
- MIDI Keyboard – The main way to play melodic instruments, basslines, and harmonies. Keys with velocity/pressure sensitivity provide more expression.
- MIDI Pads – Used for programming drums/beats or performing chromatic samples and clips. Look for velocity/pressure sensitivity.
- MIDI Faders and Knobs – Assign these to control DAW, virtual instruments, and effects parameters for easier automation.
- MIDI Pedal – A sustain pedal allows prolonging notes on compatible instruments like piano VSTs.
- MIDI Breath Controller – For adding natural expressiveness when playing wind/brass instruments.
- MIDI Drum Kits – Play electronic drum sounds using realistic pads and cymbals.
MIDI Controller Keyboards
MIDI Outboard Equipment
MIDI Software
MIDI Packs
Creative Sound Design Using MIDI
- Tweak synth parameters using MIDI continuous control messages or by mapping knobs to alter the sound in real time.
- Sequence filter cutoff, resonance, or other parameters using MIDI modulation data for dynamic motion.
- Use pitch bend and mod wheel messaging to add expressive vibrato and resonance.
- Automate filter types, attack, delay times, etc. on synth layers to evolve the sound over time.
- Layer instruments, then offset the MIDI note start times and alter individual parameters for each layer.
- Use MIDI velocity data to trigger different oscillator waveforms or filter settings on each note.
MIDI Clock Sync and Tempo
- Keeping an analog synth or drum machine locked to your DAW’s tempo during recording.
- Syncing up multiple hardware drum machines playing together.
- Using MIDI to sync effects like delay to your master time signature.
MIDI Show Control
- Triggering lighting cues from MIDI notes.
- Synchronizing visuals/projections to musical performances.
- Changing synthesizer patches in time throughout the track.
- Executing choreographed stage instrumentation.
The Future of MIDI
Conclusion
Topic | Description |
---|---|
What is MIDI? | MIDI (Musical Instrument Digital Interface) is a protocol that allows digital musical instruments, computers, and other equipment to communicate and exchange data for controlling musical performance parameters. |
How MIDI Works | MIDI transmits event messages like note on/off, pitch, velocity, control changes, program changes, etc. This data is sent over 16 channels which allows connecting multiple instruments and separating their signals. |
MIDI Hardware | Common MIDI instruments include controller keyboards, electronic drum pads, guitar controllers, etc. MIDI sound modules and synths generate audio from the MIDI data. Sequencers and recording devices capture MIDI performances. |
MIDI Software | Sequencing, notation, virtual instrument, and DAW software allow recording, editing, and playing back MIDI sequences to control softsynths, effects, and parameters. |
MIDI Controllers | Keyboards, pads, faders, knobs and pedals are used to generate and manipulate MIDI control messages to shape sound and performance attributes. |
MIDI Sync | MIDI clock allows synchronizing tempo, time signature, and sequences between multiple hardware devices and computer software. |
Sound Design | MIDI facilitates extensive real-time sound manipulation and automation for custom sound design during music production. |
The Future of MIDI | After 35+ years, MIDI remains essential to digital music workflows. The simple, flexible protocol continues to adapt to new technologies while retaining backward compatibility. |