MIDI clock

MIDI Clock sends the master deck's tempo to one MIDI output on macOS. Choose a USB MIDI device or the MIDI output on your audio interface. Your hardware needs to receive MIDI clock and use it as its external tempo source.

Enable MIDI clock

1. Connect your hardware and configure it to receive external MIDI clock.
2. Open Settings → Audio and choose a MIDI destination.
3. Turn MIDI Clock on. Play a master deck with a constant-tempo beatgrid.
4. Open the audio output menu in the top bar. Its MIDI Clock section shows the master deck, tempo, destination, and transport controls.

MIDI Clock starts disabled each time you launch the app. The destination and timing offsets are saved on this installation. Changing the destination turns clock off; enable it again for the new output.

Control the hardware sequence

Start on next bar starts the external sequence from the beginning on the next schedulable bar. Stop stops the sequence or cancels a pending start while clock pulses continue. These controls do not stop Ora DJ's decks. Re-sync aligns the pattern by restarting it on the next bar; a playing pattern continues until that boundary. Start and Re-sync both send Stop followed by Start at the boundary, so they also work after using the hardware's own playback buttons.

You can start and stop directly on your hardware without changing settings. Tempo stays synced, but a manual start may place the pattern between Ora DJ's beats. Use Re-sync to align it. The separate dropdown actions remain available regardless of Ora DJ's last command; Clock active describes clock output, not whether the hardware pattern is playing. Start and Re-sync can also retry a faulted clock, waiting for fresh timing before starting. Both are unavailable while a start is pending. Changing the master or track cancels a pending start. MIDI Continue and song-position messages are not sent.

Clock follows the current master deck, including tempo changes. When every deck stops, it keeps the last valid tempo. Scratching and backspins also hold that tempo. A seek or a master handoff with a large phase difference can show Needs re-sync; use Re-sync to align the external sequence again.

The first version requires a constant-tempo beatgrid. With a missing or variable grid, it holds the last valid tempo, or waits if no valid tempo has been received.

Adjust the timing

Use Offset in the audio output menu. Negative values send MIDI earlier; positive values send it later. The range is -100 to +100 ms. Adjustments are applied gradually while clock is running.

Calibrate by listening to a short percussive hardware pattern alongside a track with a clear beat. For a measured result, record both signals into separate channels of the same recorder and compare their attacks. MIDI transport, the hardware's sound engine, and its audio monitoring path all affect what you hear. Clock output alone cannot guarantee zero audible offset.

Offsets are saved separately for the MIDI destination, audio output route, sample rate, and buffer size. Check alignment again after changing any of these. Ora DJ does not delay its audio to compensate for MIDI.

Roland T-8 with a Scarlett 4i4

For a DIN connection, connect the Scarlett 4i4's MIDI OUT to the T-8's MIDI IN with the appropriate DIN-to-TRS Type A MIDI cable. Connect the T-8's stereo MIX OUT to Scarlett inputs 3 and 4 using a stereo breakout cable. In Focusrite Control 2, include those inputs and Ora DJ's playback channels in the monitor mix feeding your speakers.

Alternatively, connect the T-8 directly by USB and select its MIDI destination. Keep the Scarlett selected for audio and monitoring. Roland's USB setup requires A.Lnk off, a power cycle after changing it, a data-capable USB cable, and a direct connection without a hub. USB and DIN need separate timing calibration.

These are the planned reference setups; their measured timing has not yet been qualified. See Roland's T-8 reference manual and Focusrite's Scarlett 4i4 4th Generation guide for device settings and cabling.

Recover from a timing fault

A missing MIDI output, an audio-device change, or a missed scheduling deadline stops MIDI Clock and shows an explanation. Reconnect the output if needed, then press Start on next bar in the audio output menu. Ora DJ retries the clock and waits for fresh audio timing before starting the hardware on the next bar. Stop cancels the pending start. You do not need to toggle MIDI Clock in Settings.

To choose a different MIDI destination, use Settings → Audio and enable MIDI Clock for that output. The failure path leaves Ora DJ's deck transport alone.