Timecode & MIDI

Helm DJ outputs three kinds of time signal, all generated natively for sample-accurate timing and all silenced instantly by the STOP panic switch:

Signal	What it is	Typical consumer
LTC	Timecode as an audio signal	Lighting desks, media servers with an audio TC input
MTC	Timecode over MIDI	Media servers, show control software
MIDI Clock	BPM as 24 PPQ ticks	Resolume Arena, synths, anything that beat-syncs

What the timecode actually says

For LTC and MTC, the output value is the selected track’s Start Offset (set per track on the Tracks page) plus the elapsed time on the deck. Give each track a unique offset — one hour apart is the common scheme — and your desk always knows which song it’s in regardless of play order. See Building a show.

Source modes — which deck drives the output

All three signals share the same source-mode concept, set in Settings → Timecode (and separately for MIDI Clock in Settings → MIDI):

Mode	Behaviour
Auto (on-air)	Follow the deck that’s live through the mixer. Sticky through a crossfade — stays with the current deck until it goes off-air, then hands to the next on-air deck. Default, right for most shows.
Network master	Follow whichever CDJ holds the MASTER flag (the hardware MASTER button). Useful in rehearsal when nothing is on-air.
Pin to deck	One specific deck drives the output, always.

Walkthrough: LTC to a lighting desk

1. Connect an audio output (interface or headphone jack) from the Mac to the desk’s LTC input.
2. Settings → Timecode — set the Frame Rate to match the desk (24/25/30).
3. Tick Master LTC enabled, pick the Master LTC Device, and set Channel (stereo, or left/right if you’re splitting one stereo output into two feeds).
4. Choose the Source Deck mode — Auto (on-air) for a normal show.
5. Play a track on a deck and bring its fader up: the desk should read timecode = that track’s start offset + elapsed.

Pause / Resume all timecode (bottom of the Timecode tab) kills every LTC + MTC stream in one click without losing any of the routing config, and the same button brings it all back. Use it when the desk operator asks for silence on the TC line.

Walkthrough: per-deck timecode

For rigs that want a separate timecode feed per deck (e.g. two media server layers, one per turntable):

• Quick way: on the Decks page, each deck card has a Timecode dropdown — pick an LTC device or MTC port for that deck right there.
• Full control: Settings → Timecode → Per-Deck Timecode Outputs — each deck gets an LTC device + channel and/or an MTC port.

Per-deck routes override the master output for that deck. A classic setup: Deck 1 → left channel of one interface, Deck 2 → right channel of the same interface — two independent TC feeds from one stereo output.

Caution

When two decks share one audio device on split channels, keep each deck on its own channel (one left, one right). Assigning overlapping channels on the same device makes the streams fight and the output gets unstable.

MTC (MIDI Timecode)

Set the MTC Output Port in Settings → MIDI. Frame rate and drop-frame come from the shared Timecode settings. Helm DJ streams quarter-frame messages continuously and sends a full-frame message whenever the playhead jumps (track load, loop, cue), so the receiver snaps to position instead of chasing.

Per-deck MTC ports are configured in the same per-deck routing table as LTC.

MIDI Clock (BPM)

Sends the source deck’s live tempo as MIDI Clock so external apps stay beat-locked. Configure in Settings → MIDI → MIDI Clock (BPM):

Setting	Notes
Send MIDI Clock	Master enable
Output Port	MIDI Clock is system realtime — it applies to the whole port, not a channel. One BPM per port; use a dedicated (virtual) port if other MIDI shares the interface
Tempo Source	Same three modes as timecode (auto on-air / network master / pinned)
Send Start/Stop with deck transport	Sends Start when the source deck plays and Stop when it pauses. Clock ticks flow continuously either way so receivers never lose tempo lock

Walkthrough: BPM into Resolume Arena

1. Create a virtual MIDI port: Audio MIDI Setup → Window → Show MIDI Studio → IAC Driver → enable, add a bus named e.g. Helm Clock.
2. In Helm DJ: Settings → MIDI → enable Send MIDI Clock, Output Port → the IAC bus, Tempo Source → Auto.
3. In Resolume: Preferences → MIDI → enable the IAC bus as input and turn on its Clock option.
4. Play a track — Resolume’s BPM locks to the deck. Pitch-fader moves follow within a beat or two.

Small tempo wobble from the CDJ’s pitch reporting is filtered — only meaningful BPM changes are forwarded, so receivers see a stable tempo, not jitter.

MIDI cue output

Separate from all of the above: the Cue Output Port (Settings → MIDI) is the default port for MIDI actions fired by cues. One physical port can serve multiple roles — set the same port name wherever needed.

Panic behaviour

Engaging STOP silences everything at the audio/MIDI engine level:

• LTC outputs write silence
• MTC quarter-frame streams freeze
• MIDI Clock sends Stop and holds (ticks resume on clear)

Clearing STOP resumes output from the current deck position.

Defaults

A fresh install ships with: MTC format, 25 fps, no drop frame, follow transport on, LTC off, MIDI Clock off. Everything is opt-in from Settings.