wehub-resource-sync
80 lines
2.2 KiB
Python
80 lines
2.2 KiB
Python
# Copyright (c) Facebook, Inc. and its affiliates.
|
|
# All rights reserved.
|
|
#
|
|
# This source code is licensed under the license found in the
|
|
# LICENSE file in the root directory of this source tree.
|
|
# author: adefossez
|
|
|
|
import math
|
|
|
|
import torch as th
|
|
from torch.nn import functional as F
|
|
|
|
|
|
def sinc(t):
|
|
"""sinc.
|
|
|
|
:param t: the input tensor
|
|
"""
|
|
return th.where(t == 0, th.tensor(1., device=t.device, dtype=t.dtype),
|
|
th.sin(t) / t)
|
|
|
|
|
|
def kernel_upsample2(zeros=56):
|
|
"""kernel_upsample2.
|
|
|
|
"""
|
|
win = th.hann_window(4 * zeros + 1, periodic=False)
|
|
winodd = win[1::2]
|
|
t = th.linspace(-zeros + 0.5, zeros - 0.5, 2 * zeros)
|
|
t *= math.pi
|
|
kernel = (sinc(t) * winodd).view(1, 1, -1)
|
|
return kernel
|
|
|
|
|
|
def upsample2(x, zeros=56):
|
|
"""
|
|
Upsampling the input by 2 using sinc interpolation.
|
|
Smith, Julius, and Phil Gossett. "A flexible sampling-rate conversion method."
|
|
ICASSP'84. IEEE International Conference on Acoustics, Speech, and Signal Processing.
|
|
Vol. 9. IEEE, 1984.
|
|
"""
|
|
*other, time = x.shape
|
|
kernel = kernel_upsample2(zeros).to(x)
|
|
out = F.conv1d(x.view(-1, 1, time), kernel, padding=zeros)[..., 1:].view(
|
|
*other, time
|
|
)
|
|
y = th.stack([x, out], dim=-1)
|
|
return y.view(*other, -1)
|
|
|
|
|
|
def kernel_downsample2(zeros=56):
|
|
"""kernel_downsample2.
|
|
|
|
"""
|
|
win = th.hann_window(4 * zeros + 1, periodic=False)
|
|
winodd = win[1::2]
|
|
t = th.linspace(-zeros + 0.5, zeros - 0.5, 2 * zeros)
|
|
t.mul_(math.pi)
|
|
kernel = (sinc(t) * winodd).view(1, 1, -1)
|
|
return kernel
|
|
|
|
|
|
def downsample2(x, zeros=56):
|
|
"""
|
|
Downsampling the input by 2 using sinc interpolation.
|
|
Smith, Julius, and Phil Gossett. "A flexible sampling-rate conversion method."
|
|
ICASSP'84. IEEE International Conference on Acoustics, Speech, and Signal Processing.
|
|
Vol. 9. IEEE, 1984.
|
|
"""
|
|
if x.shape[-1] % 2 != 0:
|
|
x = F.pad(x, (0, 1))
|
|
xeven = x[..., ::2]
|
|
xodd = x[..., 1::2]
|
|
*other, time = xodd.shape
|
|
kernel = kernel_downsample2(zeros).to(x)
|
|
out = xeven + F.conv1d(
|
|
xodd.view(-1, 1, time), kernel, padding=zeros
|
|
)[..., :-1].view(*other, time)
|
|
return out.view(*other, -1).mul(0.5)
|