chore: import upstream snapshot with attribution

edgelm/examples/speech_synthesis/preprocessing/denoiser/resample.py

@@ -0,0 +1,79 @@
+# 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)