import random
from typing import Sequence, Union
from lhotse import CutSet
[docs]
class PerturbTempo:
"""
A transform on batch of cuts (``CutSet``) that perturbs the tempo of the recordings
with a given probability :attr:`p`.
If the effect is applied, then one of the perturbation factors from the constructor's
:attr:`factors` parameter is sampled with uniform probability.
"""
[docs]
def __init__(
self,
factors: Union[float, Sequence[float]],
p: float,
randgen: random.Random = None,
preserve_id: bool = False,
) -> None:
self.factors = factors if isinstance(factors, Sequence) else [factors]
self.p = p
self.random = randgen
self.preserve_id = preserve_id
def __call__(self, cuts: CutSet) -> CutSet:
if self.random is None:
self.random = random
return CutSet.from_cuts(
cut.perturb_tempo(
factor=self.random.choice(self.factors), affix_id=not self.preserve_id
)
if self.random.random() <= self.p
else cut
for cut in cuts
)