Timelines: Synchronisation with external clocks

isobar can synchronise with external clocks in a few different ways.

• MIDI: Sync from MIDI clock in
• MIDI: Sync to MIDI clock out
• Ableton Link Clock

Sync from MIDI clock in

A Timeline can be synchronised from an external MIDI clock:

midi_in = MidiInputDevice()
timeline = Timeline(clock_source=midi_in)
timeline.run()

MIDI transport events will be obeyed:

• start starts the timeline playback from time = 0
• stop stops the timeline
• continue resumes playback from wherever it was stopped

When synchronised to an external MIDI clock, querying the timeline's tempo will give an estimate of the current bpm based on a moving average.

Sync to MIDI clock out

You can also drive external MIDI clocks from a Timeline, by specifying the send_clock argument when creating the output device.

output_device = MidiOutputDevice(send_clock=True)
timeline = Timeline(120, output_device=output_device)
try:
    timeline.run()
except KeyboardInterrupt:
    # When ctrl-c is pressed, stop the timeline, which sends a MIDI `stop`
    # transport message to the external device.
    timeline.stop()

Ableton Link clock

Playback can be synchronised with Ableton Live or other devices that support Ableton Link clocking. Other Link processes on the same computer, or on the local network, are automatically detected.

Ensure that Ableton Live is running on the network with Link enabled. Run the below example, and you should hear that it is synchronised with Live's playback.

timeline = Timeline(clock_source="link")
timeline.schedule({
    "note": 60
}, quantize=1)
timeline.run()