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

Element	Syntax	Example
Timing (absolute)	[mm:ss.ms]	[00:30.500]
Timing (musical)	[bar.beat.tick]	[4.2.240]
Timing (relative)	[+duration]	[+500ms], [+1b]
Timing (simultaneous)	[@]	[@]
Note on	note_on ch.note vel dur	note_on 1.C4 100 1b
Control change	cc ch.controller.value	cc 1.7.127
Program change	pc ch.program	pc 1.42
Pitch bend	pb ch.value	pb 1.8192
Channel pressure	cp ch.value	cp 1.64
Poly pressure	pp ch.note.value	pp 1.C4.80
Variable	@define NAME value	@define TEMPO 120
Variable use	${NAME}	${TEMPO}
Loop	@loop N times...@end	See above
Sweep	@sweep from...to...@end	See above
Random	random(min,max)	random(60,100)
Import	@import "path"	@import "devices/..."

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