CompressDynamicRange

class auglib.transform.CompressDynamicRange(threshold_db, ratio, *, attack_time=0.01, release_time=0.02, knee_radius_db=4.0, makeup_db=0.0, clip=False, preserve_level=False, bypass_prob=None)

Compress the dynamic range.

The dynamic range of the signal is compressed by attenuating any sample whose amplitude exceeds a certain threshold_db. The intensity of the attenuation is determined by the ratio parameter (the higher the ratio, the stronger the gain reduction). To avoid heavy distortion, the gain reduction is smoothed over time with a contour that is governed by the attack_time and the release_time parameters.

The input-output characteristic also features a non-linear region (“knee”) around the threshold. The width of this region is controlled by the knee_radius_db parameter (expressed in decibels, and in absolute value): the nonlinear region is entered when the input signal exceeds a level given by threshold_db - kneeRadius_db, hence some gain reduction can be also seen before hitting the main threshold, if the knee radius is greater than zero.

Optionally, the resulting signal can be amplified (linearly) by means of the makeup_db gain parameter (expressed in decibels). Sample values can also be clipped to the interval [-1.0, 1.0] when exceeding this range: this behaviour is achieved by setting the clip argument.

Note

Setting makeup_db to None triggers a special behaviour, for which the makeup gain is computed automatically in a way that the peak level of the processed signal is equal to the original peak level (before compression).

Parameters

• threshold_db (typing.Union[float, auglib.core.observe.Base]) – threshold in decibels

• ratio (typing.Union[float, auglib.core.observe.Base]) – ratio (the higher the ratio, the stronger the gain reduction)

• attack_time (typing.Union[float, auglib.core.observe.Base]) – attack time in seconds

• release_time (typing.Union[float, auglib.core.observe.Base]) – release time in seconds

• makeup_db (typing.Union[None, float, auglib.core.observe.Base]) – optional amplification gain

• clip (typing.Union[bool, auglib.core.observe.Base]) – clip signal

• preserve_level (typing.Union[bool, auglib.core.observe.Base]) – if True the root mean square value of the augmented signal will be the same as before augmentation

• bypass_prob (typing.Union[float, auglib.core.observe.Base, None]) – probability to bypass the transformation

Examples

Attenuate all samples of a speech signal above -15 dB by a factor of 4.

>>> import audb
>>> import audiofile
>>> import audplot
>>> import auglib
>>> transform = auglib.transform.CompressDynamicRange(-15, 1 / 4)
>>> 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)

__call__()

CompressDynamicRange.__call__(signal, sampling_rate=None)

Apply transform to signal.

Parameters

• signal (numpy.ndarray) – signal to be transformed

• sampling_rate (typing.Optional[int]) – sampling rate in Hz

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

CompressDynamicRange.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

CompressDynamicRange.borrowed_arguments

Returns borrowed arguments.

Returns

Dictionary with borrowed arguments.

from_dict()

static CompressDynamicRange.from_dict(d, root=None, **kwargs)

Return type

audobject.core.object.Object

from_yaml()

static CompressDynamicRange.from_yaml(path_or_stream, **kwargs)

Return type

audobject.core.object.Object

from_yaml_s()

static CompressDynamicRange.from_yaml_s(yaml_string, **kwargs)

Return type

audobject.core.object.Object

hidden_arguments

CompressDynamicRange.hidden_arguments

Returns hidden arguments.

Returns

List with names of hidden arguments.

id

CompressDynamicRange.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

CompressDynamicRange.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

CompressDynamicRange.resolvers

Return resolvers.

Returns

Dictionary with resolvers.

short_id

CompressDynamicRange.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()

CompressDynamicRange.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()

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

Convert duration value to samples.

Return type

int

to_yaml()

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

Save object to YAML file.

Parameters

• path_or_stream (typing.Union[str, typing.IO]) – file path or stream

• include_version (bool) – add version to class name

to_yaml_s()

CompressDynamicRange.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