MMD Writing Skill

MMD Writing Skill

Overview

This skill helps you write MIDI Markdown (MMD) files - a human-readable, text-based format for creating MIDI sequences and live performance automation. MMD supports all MIDI devices with device-specific libraries for Neural DSP Quad Cortex, Eventide H90, and Line 6 Helix family.

Quick Start Template

Every MMD file starts with YAML frontmatter:

---
title: "Song or Automation Name"
author: "Your Name"
midi_format: 1          # 0=single track, 1=multi-track sync
ppq: 480                # Resolution (pulses per quarter note)
default_channel: 1      # MIDI channel 1-16
default_velocity: 100   # Note velocity 0-127
tempo: 120              # BPM
time_signature: [4, 4]  # [numerator, denominator]
---

@import "devices/​quad_cortex.mmd"  # Optional device library

@define MAIN_TEMPO 120

[00:00.000]
- tempo ${MAIN_TEMPO}
- marker "Start"

[00:01.000]
- note_on 1.C4 100 1b

Core Concepts

1. Timing Systems (Choose One Per Event)

MMD supports four timing paradigms:

Absolute Time (mm:ss.milliseconds):

[00:00.000]    # Start at 0 seconds
[00:01.500]    # 1.5 seconds
[01:23.250]    # 1 minute, 23.25 seconds

Musical Time (bars.beats.ticks):

[1.1.0]        # Bar 1, beat 1, tick 0
[2.3.240]      # Bar 2, beat 3, tick 240

Requires tempo and time_signature in frontmatter

Relative Timing (delta from previous):

[+500ms]       # 500 milliseconds after previous
[+1b]          # 1 beat after previous
[+2.0.0]       # 2 bars after previous

Simultaneous (same time as previous):

[@]            # Execute at same time as previous event

2. Essential MIDI Commands

Notes (with automatic note-off):

- note_on 1.C4 100 1b           # Channel.Note Velocity Duration
- note_on 1.60 127 500ms        # Using MIDI note number
- note_on 2.D#5 80 2b           # Sharps/​flats supported

Program Change (load presets):

- program_change 1.42           # Channel.Program (0-127)
- pc 1.5                        # Shorthand

Control Change (automation):

- control_change 1.7.127        # Channel.Controller.Value
- cc 1.7.127                    # Shorthand (Volume max)
- cc 1.10.64                    # Pan center
- cc 1.11.100                   # Expression

Common CC Numbers:

• CC#1: Mod Wheel
• CC#7: Volume
• CC#10: Pan
• CC#11: Expression
• CC#64: Sustain Pedal
• CC#74: Filter Cutoff

Pitch Bend:

- pitch_bend 1.0                # Center (no bend)
- pb 1.8192                     # Alternative center
- pb 1.+2000                    # Bend up
- pb 1.-4096                    # Bend down

# Pitch bend modulation (vibrato, sweeps, envelopes)
- pb 1.wave(sine, 8192, freq=5.5, depth=5)     # Vibrato
- pb 1.curve(-4096, 4096, ease-in-out)         # Pitch sweep
- pb 1.envelope(ar, attack=0.5, release=1.0)   # Pitch envelope

Aftertouch/​Pressure:

# Channel Pressure (monophonic aftertouch)
- channel_pressure 1.64
- cp 1.64                       # Shorthand

# Polyphonic Aftertouch (per-note pressure)
- poly_pressure 1.C4.80
- pp 1.C4.80                    # Shorthand

# Pressure modulation (swells, envelopes)
- cp 1.curve(0, 127, ease-in-out)              # Pressure swell
- cp 1.envelope(adsr, attack=0.2, decay=0.1, sustain=0.8, release=0.3)
- pp 1.60.wave(sine, 64, freq=3.0, depth=40)   # Per-note vibrato

Meta Events:

- tempo 120                     # Set BPM
- time_signature 4/​4            # Set time signature
- marker "Chorus"               # Add marker
- text "Performance note"       # Add text event

3. Advanced Features

Variables:

@define MAIN_TEMPO 120
@define VERSE_PRESET 10

[00:00.000]
- tempo ${MAIN_TEMPO}
- pc 1.${VERSE_PRESET}

# With expressions
@define NEXT_PRESET ${VERSE_PRESET + 1}

Loops (eliminate repetition):

@loop 4 times at [00:00.000] every 1b
  - note_on 1.C4 100 0.5b
@end

# Drum pattern
@loop 16 times at [1.1.0] every 1b
  - note_on 10.C1 100 0.1b      # Kick
  - note_on 10.D1 80 0.1b       # Snare
@end

Sweeps (smooth automation):

# Volume fade in
@sweep from [00:00.000] to [00:04.000] every 100ms
  - cc 1.7 ramp(0, 127)
@end

# With curve types
@sweep from [1.1.0] to [5.1.0] every 8t
  - cc 1.74 ramp(0, 127, exponential)
@end

Ramp types: linear, exponential, logarithmic, ease-in, ease-out, ease-in-out

Random Values (humanization & generative music):

# Random velocity (60-100)
- note_on 1.C4 random(70,100) 0.5b

# Random note selection
- note_on 1.random(C3,C5) 80 0.5b

# Random CC values
- cc 1.74.random(50,90)

# In loops for variation
@loop 8 times at [00:16.000] every 0.25b
  - cc 1.74.random(40,100)
@end

Supported in: velocity, note ranges (with note names), CC values, beat durations NOT supported in: timing expressions, @define values, numeric note IDs

Modulation (curves, waves, envelopes):

Bezier Curves - Smooth parameter transitions:

- cc 1.74.curve(0, 127, ease-out)        # Natural filter opening
- cc 1.7.curve(0, 100, ease-in)          # Volume fade-in
- cc 1.11.curve(0, 127, ease-in-out)     # Expression swell

Waveforms (LFO) - Periodic modulation:

- cc 1.1.wave(sine, 64, freq=5.0, depth=10)      # Vibrato
- cc 1.7.wave(sine, 100, freq=4.0, depth=30)     # Tremolo
- cc 1.74.wave(triangle, 64, freq=0.5, depth=60) # Filter sweep

Envelopes - Dynamic parameter shaping:

- cc 1.74.envelope(adsr, attack=0.5, decay=0.3, sustain=0.7, release=1.0)
- cc 1.74.envelope(ar, attack=0.01, release=0.2)
- cc 1.74.envelope(ad, attack=0.02, decay=0.5)

Device Libraries (high-level control):

@import "devices/​quad_cortex.mmd"
@import "devices/​eventide_h90.mmd"

# Use readable aliases instead of raw MIDI
- cortex_load 1.2.0.5       # Load setlist 2, scene 0, preset 5
- h90_preset 2.20           # Load H90 preset 20

Available: quad_cortex, eventide_h90, helix, hx_stomp, hx_effects, hx_stomp_xl

Custom Aliases:

@alias my_preset pc.{ch}.{preset} "Load preset"

# Usage
- my_preset 1.42

# Multi-command alias
@alias cortex_load {ch}.{setlist}.{group}.{preset} "Full preset load"
  - cc {ch}.32.{setlist}
  - cc {ch}.0.{group}
  - pc {ch}.{preset}
@end

# With defaults and enums
@alias volume_set {ch}.{value=100} "Set volume"
  - cc {ch}.7.{value}
@end

@alias routing {ch}.{mode=series:0,parallel:1} "Set routing"
  - cc {ch}.85.{mode}
@end

Comments:

# Single line comment

## Section header (H2 style)

- pc 1.5    # Inline comment

/​*
  Multi-line comment block
*/

// C-style comment

Common Patterns

See EXAMPLES.md for comprehensive pattern library including:

• Drum patterns (GM drum map on channel 10)
• Chord progressions
• Volume automation (fades, swells)
• Expression pedal automation
• Humanized hi-hat patterns
• Generative ambient pads

Validation Rules

Critical Rules (avoid these errors):

1. ✅ Always start with timing marker

   [00:00.000]
   - note_on 1.C4 100 1b
   

2. ✅ Timing must increase monotonically

   [00:05.000]
   - note_on 1.C4 100 1b
   [00:10.000]  # Must be after 00:05.000
   - note_on 1.D4 100 1b
   

3. ✅ MIDI value ranges

   • Values: 0-127
   • Channels: 1-16
   • Notes: 0-127 (C-1 to G9)
   • Pitch bend: -8192 to +8191 or 0 to 16383

4. ✅ No random() in timing or @define

   # ❌ Wrong
   [00:08.random(-10,10)]
   @define VEL random(40,60)
   
   # ✅ Correct
   [00:08.000]
   - note_on 1.C4 random(40,60) 1b
   

Best Practices

1. Use musical timing for music - Adjusts with tempo changes
2. Use variables for reusable values - Easier to maintain
3. Add comments and markers - Improves readability
4. Use loops to avoid repetition - Cleaner, more maintainable
5. Import device libraries - More readable than raw MIDI
6. Validate before compiling - Catch errors early

Workflow

# 1. Write MMD file
# 2. Validate syntax
mmdc validate song.mmd

# 3. Inspect events
mmdc inspect song.mmd

# 4. Compile to MIDI
mmdc compile song.mmd -o output.mid

# 5. Test playback
mmdc play song.mmd --port 0

Additional Resources

• REFERENCE.md - Complete syntax reference and detailed explanations
• EXAMPLES.md - Pattern library with working examples
• spec.md - Complete MMD language specification (in project root)
• examples/​ - 49 working example files organized by category
• docs/​user-guide/​ - User documentation
• docs/​dev-guides/​ - Developer implementation guides

Related Skills

• mmd-cli - For compiling, validating, playing MMD files, and managing device libraries
• mmd-device-library - For creating custom device libraries
• mmd-debugging - For troubleshooting MMD files

Quick Syntax Reference

For complete documentation, see the additional resource files in this skill directory.