most LLMs are DJs

Boiler room but it's a datacenter evaporative cooling tower.

Fork of cloudygetty-ai/mixxx-mcp, an MCP server that lets AI agents control Mixxx over a virtual MIDI port.

How it works

Claude ──MCP──▶ python server ──▶ virtual MIDI port "mixxx-mcp"
                                        │  CC messages
                                        ▼
                              Mixxx controller script (JS)
                                  engine.setValue(...)

That's the write path, and it's the only path. Upstream also promised a read path (the Mixxx JS posting state back out), but Mixxx's embedded JS engine has no XMLHttpRequest and no sockets, so it can never work — the state tools (get_deck_state etc.) always come back empty. The agent reads Mixxx's log file instead (every command echoes a [mixxx-mcp] SET ... line, and track loads show up as analyzer lines) plus Mixxx's SQLite library DB for titles, BPMs, and durations. The log flushes minutes late, so the agent mixes on wall-clock math and confirms after the fact. Flying the decks on log-tail and SQL is half the fun.

What's different from upstream

• mixxx-mcp.js: top-level const → var + explicit globalThis export (Mixxx's QJSEngine can't see top-level const), and setTimeout → engine.beginTimer (there is no setTimeout in Mixxx JS).
• mixxx-mcp.midi.xml: regenerated so all 128 CCs script-bind to MixxxMCP.handleCC — the original bound control names directly, which Mixxx rejects as an invalid mapping and silently disables.
• Track-loading controls added (CCs 117–123): library cursor next/prev and load-to-deck. This is what lets the agent choose its own tracks.
• main.py logs to stderr (it was corrupting the MCP stdio transport).
• The HTTP state server (dead weight, see above) accepts MIXXX_MCP_STATE_PORT so a second instance doesn't crash on a busy port.
• .claude/skills/run-mixxx-mcp/: an agent skill + driver.py harness — bring-up checks, deploy, a log watcher, library queries, a smoke test, and a standalone MCP client REPL for driving Mixxx with no registration at all.
• scripts/energy.sh: ffmpeg RMS energy profiler (~1.3 s per track) that finds where a track's intro ends and its outro begins, so transitions land while the track still has life in it, not at a fixed "70 seconds before the end."

Quickstart (macOS)

Tested on an Intel iMac with Mixxx 2.5.6 from the official DMG.

python3.12 -m venv .venv
.venv/bin/pip install mcp python-osc python-rtmidi

# register with Claude Code (user scope)
claude mcp add mixxx-mcp -s user -- $PWD/.venv/bin/python $PWD/main.py

# copy the controller mapping into Mixxx's (sandboxed) controllers dir
.venv/bin/python .claude/skills/run-mixxx-mcp/driver.py deploy

Bring-up order matters:

1. Start the MCP server first — it creates the MIDI port. (A Claude Code session does this for you.)
2. Then start Mixxx.
3. Then — every time Mixxx or the server restarts — untick and re-tick Enabled under Preferences ▸ Controllers ▸ mixxx-mcp. Mixxx never reattaches on its own; commands sent to a stale port report success and vanish into the void. This is the number-one gotcha.
4. Verify: driver.py status, send a control, then look for the SET line with driver.py log (patience — the log buffers).

Tools

Tool	Description
play(deck) / stop(deck) / cue(deck)	Transport
sync(deck)	Enable sync (can only enable — disable via send_control sync_enabled 0)
set_volume(deck, value)	Channel fader 0.0–1.0
set_crossfader(value)	Crossfader −1.0–1.0
set_eq(deck, low, mid, high)	EQ bands 0.0–4.0
set_pregain(deck, value)	Trim 0.0–4.0
set_rate(deck, value) / nudge_tempo(...)	Pitch / tempo nudge
set_loop / exit_loop / halve_loop / double_loop	Beat loops
set_hotcue / goto_hotcue / clear_hotcue	Hotcues 1–8
beatjump(deck, beats)	Jump ±N beats
toggle_effect / set_effect_mix	Effects
send_control(group, key, value)	Raw escape hatch — anything in the Mixxx controls reference
get_deck_state / get_mixer_state / get_all_state	Always empty (see above) — read the log instead

Credits

Forked from cloudygetty-ai/mixxx-mcp Mixxx

License

All rights reserved. You must only use this in violation of my intellectual property rights.