ArkComposer

Current packaged release: 1.2.5.12

Windows score editor and AI-assisted composition workstation.

Write, edit, arrange, and refine music in a full score editor, then use built-in AI tools or MCP-connected clients when you want generation help.

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👨‍💻 About the Author

Park Byoung Gu (박병구)

Director & SW Group Manager at AXT (Ajinextek) — a leading company in industrial motion controller markets — where he leads software R&D.

ArkComposer is a personal hobby project, built on weekends and spare moments, driven by a deep love of music.

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What Makes ArkComposer Different

• Full score editing and composition tools live in one workflow instead of separate notation and generator apps
• Edit Measure (MIDI) gives you a modeless piano-roll editor for precise measure-level repair, timing edits, velocity shaping, and AI-assisted rewriting
• Built-in composition helpers cover rhythm, melody variation, chord suggestion, voice leading, accompaniment, and AI generation
• Melody recording can capture microphone input or system sound playback and convert the detected melody into editable score notation
• An MCP server is built into the app, so external AI clients can control the same score editor when needed
• Visual analysis overlays and score-aware editing tools stay tied to the musical structure instead of raw MIDI only

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Features

Top-Bar Workflow

• Undo / Redo stays at the far left for quick recovery
• Edit Measure opens Edit Measure (MIDI) for the current measure selection
• Measure Select, Note Select, and Score Edit split selection from direct score editing
• Pinned note and eraser tools can switch the app into score editing immediately
• Rhythm, Melody, Helper, and AI Helper menus are grouped on the right side of the top bar
• A status bar below the top menu shows the current mode, tool, track, selected measures, rhythm, melody, and AI state

Score Editing

• Multi-track score editor with treble and bass clef support
• Note input: whole, half, quarter, 8th, 16th, 32nd (+ dotted variants)
• Accidentals, dynamics (p, mf, f, cresc, dim), tempo marks (accel, rit)
• Key signature: major/minor, all 15 keys, 3 apply modes (pitch-fixed / position-fixed / transpose)
• Time signatures: 4/4, 3/4, 2/4, 6/8, 12/8
• Chord symbol display above measures
• Lyrics editor with per-measure editing
• Multi-document tabs with independent undo/redo per tab

Edit Measure (MIDI)

• Piano-roll style editor for note timing, duration, pitch, and velocity inside selected measures
• Edit / Insert / Delete / Tie modes for fast repair without leaving the score workflow
• Track-wide measure navigation slider for moving across the active track while staying in the same editor
• Built-in playback controls for checking only the current track or all tracks
• Velocity popup editor for shaping dynamics inside the current measure range
• Designed for repeated measure cleanup and detailed note-level correction after generation or manual entry

Track Management

• Add, delete, merge, split (by pitch range), reorder tracks
• Hide/show individual tracks
• Per-track instrument settings: SoundFont, Program (0–127), MIDI Channel, Bank MSB/LSB, Volume, Pan, Percussion

Compose Assist

• Rhythm reassigns rhythm patterns to selected measures
• Melody applies transforms such as inversion and other note-sequence variations
• Melody recording supports mic-in or sound playback capture, then converts the detected melody into editable score notes
• Helper groups chord suggestion, voice leading, accompaniment, and composition guidance
• AI Helper groups AI-backed generation tools for voicing and accompaniment
• Voice Leading provides tunable parameters for harmonic line shaping and chord motion
• Accompaniment supports Arpeggio, Chord Beat, Drum Groove, and AI-driven styles

AI Voicing and AI Accompaniment

• AI Voicing is available from the AI Helper menu and directly inside Edit Measure (MIDI)
• Use AI Voicing when the current track already has harmonic intent but needs cleaner voicing, redistribution, or regeneration
• AI Accomp inside Edit Measure (MIDI) generates accompaniment that follows the current melody and harmony while staying in the measure-edit workflow
• AI accompaniment styles include AI Chord Beat, AI Arpeggio, AI Free, AI Free (Melody Variation), and AI Drum Beat
• Built-in ONNX and TinyGRU models can be selected from the app for local generation

AI Integration via MCP

• Full MCP server built into the app (stdio and TCP modes)
• Compatible with Claude Code and other MCP-capable clients
• Compose through natural language, then continue refining the result in the score editor or Edit Measure (MIDI)
• Scope control includes targeted edits such as selected range and whole-song operations
• MCP exposes self-documentation so connected AI clients can inspect available tools

Audio & Export

• Playback with SoundFont synthesis (.sf2)
• Record melody from microphone input or system sound playback and convert it to editable score notation
• Export audio: WAV (lossless) / MP3 (compressed, requires lame.exe in Tools/)
• Export score: PDF / PNG / JPG
• Export video: MP4/H.264 with score frames, playback cursor, and optional AAC audio via bundled FFmpeg
• Import / Export MIDI
• Native save format: .ark using ArkScore v3 compact JSON
• Legacy score formats remain readable: .json, .arkscore, .arkscore.json

Plugin Filter Structure

• Built-in audio effect filters (Distortion, Echo, and more)
• Extensible plugin architecture for custom effects

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AI Composition via MCP

Mode 1 — stdio (Claude Code) ✅ Tested

Launch ArkComposer in MCP stdio mode:

ArkComposer.exe --mcp-mode

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "arkcomposer": {
      "command": "C:/path/to/ArkComposer.exe",
      "args": ["--mcp-mode"]
    }
  }
}

Then talk to Claude Code:

"Create an 8-bar melody in C major, 4/4 time"
"Add an arpeggio accompaniment track"
"Apply jazz voice leading to measures 1–4"
"Continue the melody for 4 more measures"

Mode 2 — TCP (Codex CLI and others) ✅ Tested

1. Launch ArkComposer normally
2. In the left palette, click MCP Server
3. Enter a TCP port (e.g. 7890) → Click Start
4. Connect your MCP-compatible client to localhost:7890

Note on ChatGPT: ChatGPT does not natively support MCP.
To use ArkComposer with ChatGPT, you need to implement a separate OpenAPI server that bridges ChatGPT function calls to ArkComposer's MCP tools.

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MCP Tool Surface

ArkComposer exposes a full score editing API over MCP:

Category	Tools
Score reading	get_score, get_score_range, get_score_compact, get_score_range_compact
Note editing	add_note, add_notes_batch, add_notes_compact, change_note, delete_note
Track management	add_track, delete_track, set_track_props
Measure management	add_measure, delete_measure, delete_measures_range, clear_measure, set_measure_props
Document	new_song, set_title, undo

Full AI usage guide: docs/HowToUse_ArkCompoerForLLM.md Also available at runtime via MCP resource: arkcomposer://docs/how-to-use-llm

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Installation

Requirements

• Windows 10 / 11 (64-bit)
• MP3 export uses Tools/lame.exe.
• MP4 video export uses Tools/ffmpeg.exe.

SoundFonts

Place .sf2 files in the SoundFonts/ folder.
ArkComposer ships with:

• GeneralUser GS v1.471.sf2 — GeneralUser GS License v2.0 (S. Christian Collins)
• GeneralUser_GS_SoftSynth_v1.44.sf2 — GeneralUser GS License v2.0 (S. Christian Collins)

Download

👉 Latest Release

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Roadmap

• macOS / Linux support (C++ / JUCE core is cross-platform ready)
• Cloud sync
• Plugin marketplace
• More AI model integrations

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Credits

Component	Author	License
JUCE Framework	Raw Material Software	JUCE Starter
GeneralUser GS v1.471.sf2	S. Christian Collins	GeneralUser GS License v2.0
GeneralUser_GS_SoftSynth_v1.44.sf2	S. Christian Collins	GeneralUser GS License v2.0
FluidSynth	Peter Hanappe and contributors	LGPL 2.1
LAME MP3 Encoder	Mark Taylor and contributors	LGPL 2
FFmpeg	FFmpeg developers / Gyan.dev Windows build	GPLv3 for the bundled static essentials build
Demucs / HTDemucs-6S ONNX model	Meta / Facebook Research; ONNX conversion artifact referenced by Tools/demucs/manifest.json	Demucs upstream MIT; preserve model/source attribution and applicable artifact terms
ONNX Runtime	Microsoft and contributors	MIT
SDL3	Sam Lantinga and contributors	zlib
libsndfile	Erik de Castro Lopo and contributors	LGPL 2.1

See Credits.txt for full details.

Third-Party License Notices

• FFmpeg is included as a separate Tools/ffmpeg.exe executable for audio conversion/analysis workflows. The bundled binary reports a Gyan.dev essentials build configured with GPL/version3 options, so FFmpeg copyright, GPL terms, build/source availability, and upstream notices must be preserved when distributing ArkComposer.
• Demucs / HTDemucs-6S is included as a local AI model asset for audio source-separation-assisted workflows. Keep the Demucs/Meta attribution, model artifact source information from Tools/demucs/manifest.json, and any applicable model artifact license notice with redistribution.
• ONNX Runtime is included as onnxruntime.dll and onnxruntime_providers_shared.dll for local ONNX inference. Preserve the Microsoft/contributor attribution and MIT license notice.
• GeneralUser GS SoundFont files are included as bundled sound assets. Preserve the S. Christian Collins attribution and the GeneralUser GS License v2.0 notice.
• These third-party components are not owned by ArkComposer. Their licenses apply to their own binaries, libraries, models, and assets separately from the ArkComposer application license.

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License

ArkComposer is free to download and use.
Music created with ArkComposer may be used for personal or commercial purposes without restriction.
Redistribution of ArkComposer itself is not permitted.
Source code is proprietary and not included in this distribution.

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Built with C++ and JUCE
Website: arkcomposer.com