LowPass

class auglib.transform.LowPass(cutoff, *, order=1, design='butter', preserve_level=False, bypass_prob=None)[source]

Run audio signal through a low-pass filter.

Parameters
Raises

ValueError – if design contains a non-supported value

Examples

Filter a speech signal with a 2000 Hz, 2th order low pass.

>>> import audb
>>> import audiofile
>>> import audplot
>>> import auglib
>>> transform = auglib.transform.LowPass(2000, order=2)
>>> files = audb.load_media("emodb", "wav/03a01Fa.wav", version="1.4.1")
>>> signal, sampling_rate = audiofile.read(files[0])
>>> augmented_signal = transform(signal, sampling_rate)
>>> audplot.waveform(augmented_signal)
../_images/auglib-transform-LowPass-1.png

Inspect its magnitude spectrum.

>>> import audmath
>>> import matplotlib.pyplot as plt
>>> import seaborn as sns
>>> sigs = [signal, augmented_signal]
>>> colors = ["#5d6370", "#e13b41"]
>>> for sig, color in zip(sigs, colors):
...     magnitude, f = plt.mlab.magnitude_spectrum(sig, Fs=sampling_rate)
...     # Smooth magnitude
...     magnitude = np.convolve(magnitude, np.ones(14) / 14, mode="same")
...     plt.plot(f, audmath.db(magnitude), color=color)
>>> plt.xlim([10, 8000])
>>> plt.ylim([-100, -45])
>>> plt.ylabel("Magnitude / dB")
>>> plt.xlabel("Frequency / Hz")
>>> plt.legend(["signal", "augmented signal"])
>>> plt.grid(alpha=0.4)
>>> sns.despine()
>>> plt.tight_layout()
../_images/auglib-transform-LowPass-3.png

The low pass can also filter signals added by other transforms.

>>> transform = auglib.transform.Mix(
...     auglib.transform.WhiteNoiseGaussian(),
...     snr_db=10,
...     transform=auglib.transform.LowPass(2000, order=2),
... )
>>> augmented_signal = transform(signal, sampling_rate)
>>> audplot.waveform(augmented_signal)
../_images/auglib-transform-LowPass-4.png

__call__()

LowPass.__call__(signal, sampling_rate=None)

Apply transform to signal.

Parameters
Return type

numpy.ndarray

Returns

augmented signal

Raises

  • ValueError – if the signal shape is not support by chosen transform parameters

  • ValueError – if sampling_rate is None, but the transform requires a samling rate

  • RuntimeError – if the given sampling rate is incompatible with the transform

arguments

LowPass.arguments

Returns arguments that are serialized.

Returns

Dictionary of arguments and their values.

Raises

RuntimeError – if arguments are found that are not assigned to attributes of the same name

Examples

>>> import audobject.testing
>>> o = audobject.testing.TestObject('test', point=(1, 1))
>>> o.arguments
{'name': 'test', 'point': (1, 1)}

borrowed_arguments

LowPass.borrowed_arguments

Returns borrowed arguments.

Returns

Dictionary with borrowed arguments.

from_dict()

static LowPass.from_dict(d, root=None, **kwargs)
Return type

audobject.core.object.Object

from_yaml()

static LowPass.from_yaml(path_or_stream, **kwargs)
Return type

audobject.core.object.Object

from_yaml_s()

static LowPass.from_yaml_s(yaml_string, **kwargs)
Return type

audobject.core.object.Object

hidden_arguments

LowPass.hidden_arguments

Returns hidden arguments.

Returns

List with names of hidden arguments.

id

LowPass.id

Object identifier.

The ID of an object ID is created from its non-hidden arguments.

Returns

object identifier

Examples

>>> class Foo(Object):
...    def __init__(self, bar: str):
...        self.bar = bar
>>> foo1 = Foo('I am unique!')
>>> foo1.id
'893df240-babe-d796-cdf1-c436171b7a96'
>>> foo2 = Foo('I am different!')
>>> foo2.id
'9303f2a5-bfc9-e5ff-0ffa-a9846e2d2190'
>>> foo3 = Foo('I am unique!')
>>> foo1.id == foo3.id
True

is_loaded_from_dict

LowPass.is_loaded_from_dict

Check if object was loaded from a dictionary.

Returns True if object was initialized from a dictionary, e.g. after loading it from a YAML file.

Returns

True if object was loaded from a dictionary,

otherwise False

resolvers

LowPass.resolvers

Return resolvers.

Returns

Dictionary with resolvers.

short_id

LowPass.short_id

Short object identifier.

The short ID consists of eight characters and is created from its non-hidden arguments.

Returns

short object identifier

Examples

>>> class Foo(Object):
...    def __init__(self, bar: str):
...        self.bar = bar
>>> foo1 = Foo('I am unique!')
>>> foo1.id
'893df240-babe-d796-cdf1-c436171b7a96'
>>> foo1.short_id
'171b7a96'
>>> foo2 = Foo('I am different!')
>>> foo2.short_id
'6e2d2190'
>>> foo3 = Foo('I am unique!')
>>> foo1.short_id == foo3.short_id
True

to_dict()

LowPass.to_dict(*, include_version=True, flatten=False, root=None)

Converts object to a dictionary.

Includes items from audobject.Object.arguments. If an argument has a resolver, its value is encoded. Usually, the object can be re-instantiated using audobject.Object.from_dict(). However, if flatten=True, this is not possible.

Parameters

  • include_version (bool) – add version to class name

  • flatten (bool) – flatten the dictionary

  • root (typing.Optional[str]) – if file is written to disk, set to target directory

Return type

typing.Dict[str, typing.Union[bool, datetime.datetime, dict, float, int, list, None, str]]

Returns

dictionary that represent the object

Examples

>>> import audobject.testing
>>> o = audobject.testing.TestObject('test', point=(1, 1))
>>> o.to_dict(include_version=False)
{'$audobject.core.testing.TestObject': {'name': 'test', 'point': [1, 1]}}
>>> o.to_dict(flatten=True)
{'name': 'test', 'point.0': 1, 'point.1': 1}

to_samples()

LowPass.to_samples(value, sampling_rate=None, *, length=None, allow_negative=True)

Convert duration value to samples.

Return type

int

to_yaml()

LowPass.to_yaml(path_or_stream, *, include_version=True)

Save object to YAML file.

Parameters

to_yaml_s()

LowPass.to_yaml_s(*, include_version=True)

Convert object to YAML string.

Parameters

include_version (bool) – add version to class name

Return type

str

Returns

YAML string

Examples

>>> import audobject.testing
>>> o = audobject.testing.TestObject('test', point=(1, 1))
>>> print(o.to_yaml_s(include_version=False))
$audobject.core.testing.TestObject:
  name: test
  point:
  - 1
  - 1