MIDI In-Depth Notes

MIDI Overview

  • Definition: MIDI (Musical Instrument Digital Interface) is a communication protocol that allows musical information to be sent, received, and transmitted between hardware and software.

  • Importance: Enables universal communication of musical data across various platforms such as Digital Audio Workstations (DAWs), music notation software, hardware instruments, and MIDI instruments (e.g., keyboards, drum pads).

MIDI Functions

  • Encoding and Distribution: MIDI allows encoding and sharing of musical information, which can be represented in standard western notation and exported as MIDI files for use in DAWs.

  • Specifications: Includes both software specifications for encoding musical events and hardware specifications for cables and interfaces.

  • Universal Compatibility: MIDI is easily editable and compatible across different systems and devices.

What MIDI Is Not

  • Non-Audio: MIDI does not transmit audio or create sounds; it is a set of instructions representing musical events.

  • General MIDI: A collection of basic instruments in computers, allowing playback of MIDI data without external instruments.

  • Editable Arrangements: MIDI allows easy swapping of instruments, enabling flexible arrangement and composing.

Using MIDI in Ableton Live

  • Instrument Control: MIDI can control various instruments (synths, drum machines, etc.) within Ableton Live.

  • Recording MIDI: MIDI keyboards can record MIDI data into clips, which can then run external gear or be manipulated within Ableton.

  • MIDI Mapping: MIDI controllers can be mapped to parameters within Ableton for customized control.

MIDI Communication

  • Message Types: MIDI sends messages that communicate musically relevant events, control events, program changes, aftertouch messages, and system messages.

  • Musical Note Events: Pitch is encoded between 0-127, where pitch 60 corresponds to middle C.

  • Note Duration: The distance of one MIDI pitch equals 1 semitone; an octave equals 12 midi pitches.

MIDI Note Messages

  • Velocity: Accompanies pitch in each note event and indicates how hard a key is pressed (0-127 scale).

  • Note-On/Note-Off: Indicates whether a pitch should be played or stopped. A velocity above 0 signals Note-On; 0 signals Note-Off.

Control Changes and Aftertouch

  • Continuous Controller Data: Control change messages transmit data for modulation, expression, and other controls.

  • Aftertouch Messages: Provides additional modulation information upon pressing keys, allowing further control over held notes.

MIDI Connections

  • Connection Types: Devices connect via USB or dedicated MIDI cables, which have different ports: MIDI In (input), MIDI Out (output), and MIDI Thru (to daisy chain devices).

MIDI Channels

  • Channel Messaging: MIDI channels allow up to 16 different messages per cable, letting devices only respond to messages sent on specific channels.

MIDI File Characteristics

  • Data Export: A MIDI file is a compilation of timestamped MIDI messages preserving timing information.

  • Timing System: Uses ticks per quarter note for precise timing; standard is 960 ticks per quarter note.

  • Additional Information: MIDI files store tempo, tempo changes, and time signatures.

Piano Roll

  • Notation Visualization: MIDI is visualized in the Piano Roll, a grid displaying note values (Y-axis) over time (X-axis).

  • Historical Context: Invented in 1896 for player pianos; now commonly implemented in DAWs.

Quantization

  • Timing Adjustment: Quantization corrects timing discrepancies in recorded MIDI data, snapping notes to nearest specified rhythmic unit (e.g., 8th or 16th notes).

Notation Software Integration

  • Composition Support: MIDI facilitates scoring in notation software, allowing easy export back to DAWs for music production.