opendaw-mcp

<!-- mcp-name: io.github.AMEOBIUS/opendaw-mcp --> # openDAW MCP [](https://github.com/AMEOBIUS/opendaw-mcp/actions/workflows/ci.yml) [](https://opensource.org/licenses/Apache-2.0) [](https://pypi.org/project/opendaw-mcp/) [](TOOL_CATALOG.md) [](tests/) [](pyproject.toml) [](https://registry.modelcontextprotocol.io/v0.1/servers?search=io.github.AMEOBIUS/opendaw-mcp) [](https://smithery.ai/server/@macar228228/opendaw-mcp) [](https://glama.ai/mcp/servers/AMEOBIUS/opendaw-mcp) **250 MCP tools for agent-native control of [openDAW](https://github.com/andremichelle/openDAW) — a browser-based digital audio workstation.** This project wraps openDAW's internal box system and project API behind a [Model Context Protocol](https://modelcontextprotocol.io) server, allowing AI agents (Claude, GPT, Hermes, etc.) to create and manipulate music projects programmatically — tracks, instruments, effects, MIDI, automation, audio regions, rendering, and more. ## How It Works ``` AI Agent ──MCP──▶ Python Server ──Playwright──▶ Headless Chromium ──▶ openDAW (Vite dev server) ``` The MCP server launches a headless Chromium instance loaded with openDAW, then communicates via `page.evaluate()` calls into the DAW's V8 context. Every tool performs real operations on the live project — no stubs, no mocks. ## Features - **Track & Region CRUD** — create/delete/move audio, note, and automation tracks with regions - **Instrument Control** — Vaporisateur ( polysynth), Nano, Tape, Soundfont, Playfield (drum machine), MIDI output - **Effects** — Delay, Reverb, Compressor, Equalizer, Saturation, Waveshaper, Stereo, Vocoder, NeuralAmp, Maximizer - **MIDI Effects** — Arpeggio, Pitch, Velocity, Zeitgeist, Spielwerk (scriptable) - **Scriptable Devices** — Apparat (instrument), Werkstatt (audio effect), Spielwerk (MIDI effect) with JS code compilation - **Automation** — event creation, interpolation modes, tempo/signature changes - **Audio Operations** — region fades, gain, time/pitch stretch, warp markers, play modes - **Mixing** — send/return routing, buses, volume, solo/mute, mixer state inspection - **Rendering** — offline stem export with LUFS targeting, full mix render - **Clips** — session view clip CRUD, clone, consolidate, playback settings - **Groove** — groove shuffle amount and duration control - **Presets** — export/import audio unit presets, effect chain presets - **Transfer** — move regions and audio units between projects - **Project Info** — tempo map conversion (PPQN↔seconds), duration, validation, sample listing - **Notes** — pitch range, overlapping detection, advanced properties (chance, cent, playCount, playCurve) - **Modular System** — voltage modules (Gain, Delay, Multiplier, AudioInput, AudioOutput), patch cable connections - **Piano Mode** — global transpose, keyboard type, note scale, time range - **Project & Bus Metadata** — creation date, signature, AU/track count, bus labels and colors - **Debugging & Control** — screenshots, condition polling, raw JS evaluation ## Quick Start ### Prerequisites - Python 3.11+ - Node.js 20+ (for openDAW dev server) - Chromium (Playwright will install it) ### Install **From PyPI:** ```bash pip install opendaw-mcp playwright install chromium ``` **From source:** ```bash git clone https://github.com/ameobius/opendaw-mcp.git cd opendaw-mcp python -m venv venv source venv/bin/activate pip install -r requirements.txt playwright install chromium ``` ### Set Up openDAW Clone and build openDAW separately: ```bash git clone https://github.com/andremichelle/openDAW.git cd openDAW npm install npm run build # or: npx turbo run build ``` Create a headless host page (see `headless-daw/` for reference implementation). ### Run ```bash # Terminal 1: Start openDAW dev server cd openDAW npm run dev # typically serves on http://localhost:5174 # Terminal 2: Start MCP server (stdio transport, default) cd opendaw-mcp source venv/bin/activate python server.py ``` ### SSE Transport For remote deployments and registry introspection (e.g. [Glama](https://glama.ai)): ```bash MCP_TRANSPORT=sse FASTMCP_HOST=0.0.0.0 FASTMCP_PORT=8080 python server.py ``` ### CLI ```bash python server.py --help # show usage and env vars python server.py --version # print version and tool count python server.py --list-tools # list all 250 registered MCP tools ``` ### Docker ```bash # Pull pre-built image from GitHub Container Registry docker pull ghcr.io/ameobius/opendaw-mcp:1.9.8 docker run -p 8080:8080 ghcr.io/ameobius/opendaw-mcp:1.9.6 # MCP server available at http://localhost:8080/sse # Or build from source docker build -t opendaw-mcp . docker run -p 8080:8080 opendaw-mcp ``` The Docker image bundles openDAW (built from source), Vite dev server, Chromium, and the MCP server. The entrypoint starts Vite, waits for it to be ready, then launches the MCP server in SSE mode. ### Claude Desktop / MCP Client Config Add to your MCP client config (e.g. `claude_desktop_config.json`): ```json { "mcpServers": { "opendaw": { "command": "python", "args": ["path/to/opendaw-mcp/server.py"], "env": { "OPENDAW_HOST_DIR": "path/to/headless-daw", "OPENDAW_URL": "http://localhost:5174", "OPENDAW_EXPORT_DIR": "path/to/exports" } } } } ``` See `mcp.json` in the repo for a reference config. ### Environment Variables | Variable | Default | Description | |----------|---------|-------------| | `OPENDAW_HOST_DIR` | `../headless-daw` | Path to the headless openDAW host directory | | `OPENDAW_URL` | `http://localhost:5174` | URL of the running openDAW instance | | `OPENDAW_EXPORT_DIR` | `../exports` | Directory for rendered audio exports | | `NODE_BIN_DIR` | *(from PATH)* | Path to Node.js binary directory (if not on PATH) | | `MCP_TRANSPORT` | `stdio` | Transport protocol: `stdio` or `sse` | | `FASTMCP_HOST` | `127.0.0.1` | SSE server bind host | | `FASTMCP_PORT` | `8000` | SSE server bind port | ## Architecture ### HeadlessDawBridge The `HeadlessDawBridge` class manages the Playwright lifecycle: 1. Launches headless Chromium with audio autoplay enabled 2. Navigates to the openDAW URL 3. Waits for `window.DAW` and factory globals to load 4. Injects `DAW_HELPERS` — JS utility functions that eliminate boilerplate across tools ### DAW_HELPERS JavaScript helpers injected into the DAW context: - `au(i)` — get audio unit adapter by index - `track(auIdx, trackIdx)` — get track adapter - `region(au, track, reg)` — get region adapter - `instrumentAU()` — get the first instrument audio unit - `modify(fn)` — wrapper around `editing.modify()` for box mutations - `allAUs()` — list all audio unit adapters ### Tool Structure Each MCP tool follows the pattern: ```python @mcp.tool() async def tool_name(param: str) -> str: """Description.""" async def _run(): result = await bridge.page.evaluate("""...JS...""") return json.dumps(result) return await bridge.run(_run) ``` The bridge is a singleton — state persists within a single Python process. All box mutations go through `editing.modify()` as required by openDAW's transactional model. ### Input Sanitization All string parameters that are interpolated into JavaScript template literals are sanitized before evaluation — quotes, backslashes, and braces are stripped to prevent JS injection. Numeric parameters use proper `int`/`float` type annotations for FastMCP type coercion. ## DSP Scripts The `scripts/` directory contains example Werkstatt and Apparat DSP scripts: | Script | Device | Description | |--------|--------|-------------| | `werkstatt_darksat.js` | Werkstatt | Tape saturation with drive, bias, tone, mix, output gain | | `werkstatt_coldfold.js` | Werkstatt | Wavefolding + bitcrush + slew rate reduction | | `apparat_darkbass.js` | Apparat | Bass synth with sub oscillator and filter envelope | | `apparat_coldlead.js` | Apparat | Lead synth with detune and vibrato | | `spielwerk_powerchord.js` | Spielwerk | MIDI effect that generates power chord harmonies | | `spielwerk_arpeggiator.js` | Spielwerk | MIDI arpeggiator with sync | ## Examples The `examples/` directory contains 9 Python scripts demonstrating the full workflow: | Example | Description | |---------|-------------| | `create_beat.py` | Drum beat with Playfield | | `create_chord_progression.py` | Chord progression with Vaporisateur | | `mix_workflow.py` | Mixing: levels, effects, sends | | `render_stems.py` | Stem export with LUFS targeting | | `automation_sweep.py` | Filter cutoff automation | | `modular_patch.py` | Modular system with patch cables | | `full_production_pipeline.py` | Complete track: synth + drums + DSP + automation + render | | `scriptable_devices_demo.py` | All 3 scriptable device types: Apparat synth + Werkstatt DSP + Spielwerk MIDI | ## Tool Catalog See [`TOOL_CATALOG.md`](TOOL_CATALOG.md) for the complete list of 250 tools with parameters and descriptions. ## Mastering The MCP server includes a full mastering chain for streaming-ready output: 1. **Render** — `render_full` (full mixdown) or `export_stems` (per-track stems) 2. **Measure LUFS** — `measure_lufs` (ITU-R BS.1770-4 K-weighting, gated mean squares) 3. **Auto-gain** — `auto_gain` (iterative: render → measure → adjust Maximizer threshold + output volume → re-render, converges ±1 LUFS) ```python # Render full mix await server.mcp_opendaw_render_full("my_mix", 48000) # Measure loudness lufs = json.loads(await server.mcp_opendaw_measure_lufs("my_mix")) # → {"lufs_integrated": -18.3, "true_peak_db": -3.71, ...} # Auto-gain to Spotify target (-14 LUFS) result = json.loads(await server.mcp_opendaw_auto_gain("-14", "mastered", 48000, "3")) # → converges to -13.7 LUFS in 3 iterations ``` Platform targets: Spotify/YouTube -14 LUFS, Apple Music -16 LUFS, Tidal -14 LUFS. ## Limitations - **Headless only** — some UI-dependent features (file dialogs, popup-based model loading) are not available - **Single process** — bridge state doesn't persist across Python process restarts - **Upstream coupling** — tools depend on openDAW's internal box system, which can change between versions - **AU rename** — requires adapter context not available in headless mode ## Acknowledgments - [andremichelle](https://github.com/andremichelle) — creator of openDAW, an incredible browser-based DAW - [Model Context Protocol](https://modelcontextprotocol.io) — the protocol that makes agent-native tools possible ## License Apache-2.0 — see [LICENSE](LICENSE) ## Changelog ### v1.9.8 (2026-07-04) - **250 total tools** (+7 since v1.9.6) - **`set_metronome`** — dedicated metronome control (enabled, gain, beat_subdivision) - **Module-level lookup tables** — TIDAL_RATE_MAP, DELAY_SYNC_MAP, WAVESHAPER_FUNCS, REVAMP_SECTIONS extracted for testability - **+23 new unit tests** (54 total) — fraction maps, waveshaper funcs, revamp sections, safe_filename edge cases - **Official ScriptCompiler migration** — `set_script_device_code` now uses the real `ScriptCompiler` from `@opendaw/studio-adapters` instead of custom @param/@sample parser. Benefits: declaration caching (WeakMap), proper sample file cleanup, label parsing, correct worklet wrapping - **Stems export fix** — `useInstrumentOutput` changed from True→False. Stems now route through channel strip (effects, sends, volume/pan) as documented by naomiaro/opendaw-test - **`export_dry_stem`** — new tool for freeze/flatten/re-amp workflows: captures raw instrument output before effects - **`set_waveshaper_equation`** — 6 transfer functions (hardclip/cubicSoft/tanh/sigmoid/arctan/asymmetric) - **`set_crusher_crush`** — sample-rate reduction with documented crush inversion semantics - **`set_revamp_filter`** — 7 EQ sections (highpass/lowshelf/lowbell/midbell/highbell/highshelf/lowpass) with enabled/freq/gain/q/order - **`set_tidal_rate`** — musical fraction string → Tidal LFO rate index (17 entries) - **`set_delay_sync`** — musical fraction string → Delay synced time index (21 entries, includes "off") - **Effect lookup case-insensitive** — `add_effect("werkstatt")` now works alongside `Werkstatt` - **naomiaro/opendaw-test research** — 543 commits, 17 SDK doc chapters used as authoritative reference for effect parameters and box field names - **54 tests, ruff clean, CI green** ### v1.9.6 (2026-07-03) - **`measure_lufs` refactored** — 223 lines → 20 lines. Extracted `_parse_wav()` and `_compute_lufs()` helpers - **DRY: K-weighting coefficients** — duplicated if/else branches (48kHz vs else) were identical, merged into single computation - **9 new unit tests** — WAV parsing (float32/mono/stereo/PCM16/invalid/no-data) + LUFS computation (silence/full-scale/low-level/stereo) - **Social preview banner** — custom OpenGraph image for GitHub link previews - **awesome-mcp PR updated** — title and body synced to 250 tools - **GitHub topics** — 18 topics for discoverability - **31 total tests, ruff clean, CI green** ### v1.9.5 (2026-07-03) - **CLI commands** — `--version`, `--list-tools`, `--help` with full env var reference - **31 unit tests** — pytest covering `_ok`, `_err`, `_wrap_eval`, `_unwrap_eval`, `_safe_filename`, `_safe_path`, `_parse_wav`, `_compute_lufs` - **3 bug fixes found by tests:** - `_ok()` — `{"success": False}` in data overwrote the `True` flag (security fix) - `_safe_filename()` — case-sensitive extension stripping (`.MP3` not stripped) - `_safe_filename()` — Windows backslash path traversal not handled on Linux - **CI enhanced** — now runs pytest (54 tests) alongside syntax/AST/smoke/ruff checks - **PEP 561** — `py.typed` marker for type checker support - **Mastering pipeline example** — full chain: render → measure LUFS → auto-gain → stems → MP3 - **16 examples total** — all syntax-validated - **250 total tools** (added `export_dry_stem` for freeze/flatten workflows) ### v1.9.4 (2026-07-03) - **Removed 2 duplicate tools** (245 → 243) - `delete_signature_event` — superseded by `delete_signature_change` (richer: position match + index, returns updated event list) - `list_aux_sends` — superseded by `list_sends` (richer: target_bus_name, send_level_db, routing, send_pan via box-level access) - **TOOL_CATALOG.md regenerated from AST** — all 250 tools with descriptions, 32 categories - **server.json Docker tag fixed** — was stale `1.0.0`, now matches release version - **250 total tools** ### v1.9.3 (2026-07-03) - **DRY refactoring complete: 17 DAW_HELPERS, ~295 replacements, 0 raw enumeration patterns** - New helpers: `markerBoxes`, `sendBoxes`, `busBoxes`, `sampleBoxes`, `noteTrackBoxes`, `clipBoxes`, `rootClipBoxes`, `scriptParams`, `scriptSamples`, `chainBoxes` - All `pointerHub.incoming()` enumeration patterns replaced across 245 tools - CONTRIBUTING.md updated with full 17-helper reference table - 6 DRY commits, 0 regressions, CI green ### v1.9.2 (2026-07-03) - **DRY refactoring: 113+ tools migrated to `h.allAUBoxes()` / `h.auBox()` helpers** - Replaced 133 occurrences of raw `[...rootBox.audioUnits.pointerHub.incoming()].map(({box}) => box).sort(...)` boilerplate with `h.allAUBoxes()` across 113+ MCP tools - Box-level helpers eliminate ~3000 lines of duplicated AU enumeration code - E2E verified: allAUBoxes returns sorted array, auBox(i) returns box by index, count matches raw, box identity matches - **Security hardening** - Transport action enum validation (`play`, `stop`, `toggle`) — prevents JS injection - `duplicate_effect` chain_type enum validation (`audio`, `midi`) - `_safe_filename()` + `_safe_path()` helpers — `os.path.basename()` sanitization + path traversal protection on 6 render/export locations - `_unwrap_eval` bare except → `json.JSONDecodeError` - **245 total tools** (no tool count change — refactoring only) ### v1.9.1 (2026-07-03) - **2 new generic tools: Boolean & Integer effect parameter setters** - `set_effect_parameter_bool(unit_index, effect_index, parameter_name, value)` — Generic boolean field setter. Covers Compressor (lookahead, automakeup, autoattack, autorelease), Gate (inverse), Maximizer (lookahead), StereoTool (invertL, invertR, swap), NeuralAmp (mono) - `set_effect_parameter_int(unit_index, effect_index, parameter_name, value)` — Generic integer field setter. Covers Vocoder (bandCount), StereoTool (panningMixing), Fold (overSampling), Crusher (bits), Delay (version). Device-specific tools are preferred when available. - **245 total tools** ### v1.9.0 (2026-07-03) - **6 new tools: Device-Specific Parameters & NeuralAmp Model Loading** - `set_neuralamp_model(unit_index, effect_index, model_json, label, pack_id)` — Load NAM/Tone3000 model JSON directly into a NeuralAmp effect, bypassing the popup-based Select Flow. Creates NeuralAmpModelBox and links it via pointer - `set_vocoder_modulator_source(unit_index, effect_index, source)` — Set Vocoder modulator source: noise-white, noise-pink, noise-brown, self, or external - `set_vocoder_band_count(unit_index, effect_index, band_count)` — Set Vocoder filter band count (8-32) - `set_stereo_tool_panning(unit_index, effect_index, panning_mixing)` — Set StereoTool panning law (linear, equal-power) - `set_fold_oversampling(unit_index, effect_index, oversampling)` — Set Fold wavefolder oversampling (0=off, 1=2x, 2=4x) - `set_crusher_bits(unit_index, effect_index, bits)` — Set Crusher bit depth (1-16) - **250 total tools** ### v1.8.2 (2026-07-03) - **2 new tools: Audio Region Time Base & Waveform Offset** - `set_audio_region_time_base(unit_index, track_index, region_index, time_base)` — Switch duration interpretation between 'musical' (PPQN, tempo-following) and 'seconds' (fixed wall-clock) - `set_audio_region_waveform_offset(unit_index, track_index, region_index, offset)` — Set waveform display offset for visual alignment - **PR #280 closed** — andremichelle confirmed it's our bundler setup issue, not upstream. Closing as requested. - **237 total tools** ### v1.8.1 (2026-07-03) - **3 new tools: Warp Marker CRUD** — `create_warp_marker`, `delete_warp_marker`, `update_warp_marker` - `create_warp_marker(unit_index, track_index, region_index, position_beats, seconds)` — Add warp marker to stretched audio regions - `delete_warp_marker(unit_index, track_index, region_index, marker_index)` — Delete non-anchor warp marker - `update_warp_marker(unit_index, track_index, region_index, marker_index, position_beats, seconds)` — Update warp marker position/seconds (-1 = unchanged) - Enables agent-driven tempo matching: programmatically pin audio regions to musical positions - **235 total tools** ### v1.8.0 (2026-07-03) - **3 new tools: MP3/FLAC Audio Conversion** — `convert_audio`, `render_full_format`, `export_stems_format` - `convert_audio(filename, format, bitrate, quality)` — WAV→MP3/FLAC via system ffmpeg - `render_full_format(filename, format, bitrate)` — render + convert in one step - `export_stems_format(filename_prefix, format, bitrate)` — stems + convert each - Uses system ffmpeg (4.4.2), not browser WASM — more reliable in headless mode - E2E: WAV 1.01MB → MP3 0.11MB (ratio 0.106) → FLAC 0.19MB (ratio 0.194) ✅ - **Bugfix: operator precedence in 14 division+nullish coalescing expressions** - `X / Quarter ?? 0` → `(X ?? 0) / Quarter` — prevents NaN→null for position/duration fields - **Improvement: `get_track_info` now includes `exclude_piano_mode` field** - **232 total tools** ### v1.7.4 (2026-07-03) - **3 new tools: Engine Sleep/Wake + Loading Check** — `engine_sleep`, `engine_wake`, `query_loading_complete` - `engine_sleep()` — suspend audio processing to save CPU during non-audio operations - `engine_wake()` — resume audio processing - `query_loading_complete()` — check if all audio samples are loaded and ready - E2E: sleep ✅, wake ✅, loading (loaded=false, is_ready=true) ✅ - **Improvement: `get_effect_chain` + `get_midi_effect_chain`** — now return short type names (`Delay` instead of `DelayDeviceBox`), plus `class`, `minimized` fields ### v1.7.3 (2026-07-03) - **2 new tools: Instrument Automation** — `add_instrument_automation`, `list_automatable_fields` - Automate any instrument parameter: Vaporisateur cutoff/volume/ADSR, Tape flutter/wow, Playfield sample mute - Per-sample targeting via `sample_index` for Playfield - `list_automatable_fields` introspects Pointers.Automation support (18/23 on Vaporisateur) - Addresses upstream #269 (playfield mute automation) via MCP - E2E: Vaporisateur cutoff automated (3 events) ✅, 18 automatable fields ✅ ### v1.7.2 (2026-07-03) - **3 new tools: Effect Duplication + Instrument Automation** — `duplicate_effect`, `add_instrument_automation`, `list_automatable_fields` - `duplicate_effect` — duplicate single effect in-place with all params copied (audio or MIDI chain) - `add_instrument_automation` — automate any instrument parameter (Vaporisateur cutoff/volume, Tape flutter, Playfield sample mute, etc). Supports per-sample targeting via sample_index - `list_automatable_fields` — introspect which fields support Pointers.Automation (18/23 on Vaporisateur) - Addresses upstream issue #273 (Ctrl+D for audio effects) and #269 (playfield mute automation) via MCP - E2E tested: Delay duplicated with params ✅, Vaporisateur cutoff automated (3 events) ✅, 18 automatable fields detected ✅ - **Bugfix: `transport(action)` now respects action parameter** — was always toggling, now correctly handles "play", "stop", "toggle" - **Cleanup: removed unused `region_type` param** from `set_region_duration` and `set_region_mute` ### v1.7.1 (2026-07-03) - **4 new tools: Engine Control** — `engine_panic()`, `get_engine_status()`, `schedule_clip_play(clip_ids)`, `schedule_clip_stop(track_ids)` - Panic button for stuck audio, real-time engine monitoring (CPU load, position, BPM, playing state), session view clip triggering - E2E tested: get_engine_status ✅, engine_panic ✅ ### v1.7.0 (2026-07-03) - **2 new tools: DawProject Interop** — `export_dawproject(filename)`, `import_dawproject(filename)` - Export/import projects in .dawproject format (Bitwig, Ableton, rePitch compatible) - ZIP containing project.xml, metadata.xml, and audio samples - Enables cross-DAW workflow: create in openDAW → export to Bitwig, or import Bitwig project → render in openDAW - DawProject + DawProjectImport exposed as globals in headless-daw - E2E tested: export (2442 bytes, valid ZIP) → import (7 boxes, round-trip OK) ### v1.6.2 (2026-07-03) - **2 new tools: Studio Settings** — `get_studio_settings()`, `set_studio_setting(category, key, value)` - Read/write StudioPreferences: engine, visibility, editing, debug, storage, time-display, pointer - Control auto-create-output-maximizer, overlapping-regions-behaviour, enable-beta-features, auto-delete-orphaned-samples, note-audition-while-editing, and more - StudioPreferences exposed as `DAW_StudioPreferences` global in headless-daw ### v1.6.1 (2026-07-03) - **4 new tools from DAW globals research** — `set_unit_minimized`, `list_aux_sends`, `capture_realtime`, `get_sample_info` - Mixer minimize, aux send listing, realtime audio capture, sample metadata ### v1.6.0 (2026-07-03) - **DAW_HELPERS refactoring** — all 180 tools with `const p = window.DAW` migrated to `const h = window.DAW_HELPERS` pattern - Eliminated boilerplate: AU list enumeration, sort, editing.modify wrapping - Fixed 19+ pre-existing bugs: `setPosition` (api→engine), 8x missing `.sort()` on AU lists, 9x `Quarter=960` hardcode → `h.ppqn.Quarter`, 2x Python/JS scope leaks - DAW_HELPERS provides: `h.au(i)`, `h.track()`, `h.region()`, `h.modify()`, `h.allAUs()`, `h.ppqn`, `h.uuid`, `h.rootBox`, `h.api`, `h.editing`, `h.boxGraph`, `h.tempoMap`, `h.rootBoxAdapter`, `h.project` - E2E verified: 23/23 tests passing ### v1.5.2 (2026-07-02) - Sanitization: all string parameters sanitized against JS injection - Documentation: README badges, Docker, SSE, examples, mastering - CI: GitHub Actions with AST tool count verification ### v1.5.0 (2026-07-01) - Modular system: 6 MCP tools for patchable modular synthesizer - PianoMode: 6 MCP tools for piano roll view control - Freeze/unfreeze: pre-render AU to save CPU - Preset save/load: export/import AU as base64 preset - Transfer regions/AUs: deep-copy with dependency tracking