music.Sequencer

class music.Sequencer(sample_rate=<factory>, events=<factory>)[source]

Bases: object

Schedules notes and renders them as audio.

Attributes:
sample_rateinteger

The sampling frequency in Hertz, used for every note rendered and for turning each event’s start time into a sample offset. It defaults to music.get_sample_rate()’s rate when the sequencer is made.

eventslist of NoteEvent

The scheduled notes. Normally built with add_note() rather than passed in, and rendered in order of their start times rather than the order they were added.

Raises:
ValueError

If sample_rate is not positive. At zero every note rendered as no samples, and the sequence as silence of no length.

Parameters:

  • sample_rate (int)

  • events (List[NoteEvent])

See also

music.StimulationSession

phases in sequence rather than notes at offsets, for stimulation protocols.

Examples

>>> seq = Sequencer()
>>> for i, freq in enumerate([440, 550, 660]):
...     seq.add_note(freq, start=i * 0.25, duration=1.0)
>>> len(seq.events)
3
>>> seq.write("chord.wav")
__init__(sample_rate=<factory>, events=<factory>)
Parameters:

  • sample_rate (int)

  • events (List[NoteEvent])

Return type:

None

Methods

__init__([sample_rate, events])

add_note(freq, start, duration[, ...])

Add a note event to the sequencer.

render()

Render all scheduled events and return the audio array.

write(filename[, bit_depth, normalize])

Write the rendered audio to a file, as write_audio() does.

Attributes

sample_rate

events

sample_rate: int
events: List[NoteEvent]
add_note(freq, start, duration, vibrato_freq=0.0, max_pitch_dev=0.0, adsr_params=None, spatial=None)[source]

Add a note event to the sequencer.

Parameters:
freqscalar

The note’s frequency in Hertz.

startscalar

When it starts, in seconds from the start of the sequence.

durationscalar

How long it lasts, in seconds.

vibrato_freqscalar

The rate of a vibrato in Hertz. With max_pitch_dev, both nonzero, the note is rendered by note_with_vibrato().

max_pitch_devscalar

The depth of that vibrato.

adsr_paramsdict, optional

Arguments for adsr(), applied to the note.

spatialdict, optional

Arguments for localize(), which makes the note stereo.

Raises:
ValueError

If start is negative or not finite, or adsr_params or spatial names sonic_vector or sample_rate, which the sequencer supplies itself. A negative start was placed at a negative sample offset and failed with a broadcasting error, NaN and infinity failed in round() when rendering, and a second sample_rate as a TypeError there.

Parameters:
Return type:

None

render()[source]

Render all scheduled events and return the audio array.

Return type:

ndarray

write(filename, bit_depth=16, normalize=True)[source]

Write the rendered audio to a file, as write_audio() does.

Parameters:
filenamestr

The path to write: .wav or .flac.

bit_depthinteger

The bit depth of the samples written.

normalizebool

Normalize to full scale, as by default, or write the samples as they are, refusing a sound that reaches past [-1, 1], which keeps the level of a sequence written beside others.

Raises:
ValueError

If there are no notes to write: the empty render reached the normalization, which blamed a duration computed as zero. Or as write_audio() raises it.

Parameters:
Return type:

None