diquencer

Simple MIDI sequencing library for Python designed for Elektron Digitakt.

Usage

The main features of diquencer are pattern changes and track mutes.

Initialization

Start with importing Sequencer class (which is the public API of diquencer):

from diquencer import Sequencer

then you can initialize it with the following optional arguments:

sequencer = Sequencer(
    midi_channel=1,
    start_callback=lambda: print("Called when the transport starts"),
    error_callback=lambda error: print(f"Something bad happened: {error}")
)

• error argument of error_callback is an exception (it doesn't need to be handled though).
• midi_channel value should be in the range from 1 to 16.

After initialization you can get available MIDI output ports and then select one:

>>> sequencer.output_ports
['IAC Driver Bus 1', 'Digitakt Elektron MIDI']
>>> sequencer.set_output_port('Digitakt Elektron MIDI')

then you should feed the sequencer with data:

sequence_data = {
    "tempo": 134,
    "sequence": [
        {
            "name": "Intro",
            "pattern": 9,
            "bank": "A",
            "length": 4,  # length of pattern in measures
            "repetitions": 2,
            "playing_tracks": [1, 3, 7]  # tracks that are NOT muted
        },
        {
            "name": "Outro",
            "pattern": 10,
            "bank": "A",
            "length": 4,
            "repetitions": 2,
            "playing_tracks": [2, 4, 8]
        }
    ]
}
sequencer.load_sequence(sequence_data)

Running the sequencer

You can start (and stop) the playback with:

>>> sequencer.start()
>>> sequencer.is_playing
True
>>> sequencer.stop()

By default start fuction is non-blocking (the actual sequencer runs in a separate thread). You can, however, make it blocking with an optional argument:

>>> sequencer.start(blocking=True)
>>> sequencer.is_playing
False  # already finished

During playback (in non-blocking mode) you can enquire the sequencer about its status:

>>> sequencer.position
'001.0.17'  # MEASURE.QUARTER_NOTE.PULSE
>>> sequencer.current_pattern.name
'Intro'
>>> sequencer.next_pattern.name
'Outro'

Playback may be started from any pattern you want:

>>> sequencer.set_start_pattern(1)
>>> sequencer.start()
>>> sequencer.current_pattern.name
'Outro'

the argument of set_start_pattern is the index (starting from 0) of pattern in sequence list (see sequence_data in previous section).

If you wish, you can change the output MIDI channel and port (changes will have an effect after the playback restarts):

sequencer.set_midi_channel(5)