Add alaw

diffsptk/core/__init__.py

@@ -1,4 +1,5 @@
 from .acorr import AutocorrelationAnalysis
+from .alaw import ALawCompression
 from .ap import Aperiodicity
 from .b2mc import MLSADigitalFilterCoefficientsToMelCepstrum
 from .c2acr import CepstrumToAutocorrelation
@@ -27,6 +28,7 @@
 from .gmm import GaussianMixtureModeling as GMM
 from .gnorm import GeneralizedCepstrumGainNormalization
 from .grpdelay import GroupDelay
+from .ialaw import ALawExpansion
 from .idct import InverseDiscreteCosineTransform
 from .idct import InverseDiscreteCosineTransform as IDCT
 from .ifreqt2 import SecondOrderAllPassInverseFrequencyTransform

diffsptk/core/alaw.py

@@ -0,0 +1,75 @@
+# ------------------------------------------------------------------------ #
+# Copyright 2022 SPTK Working Group                                        #
+#                                                                          #
+# Licensed under the Apache License, Version 2.0 (the "License");          #
+# you may not use this file except in compliance with the License.         #
+# You may obtain a copy of the License at                                  #
+#                                                                          #
+#     http://www.apache.org/licenses/LICENSE-2.0                           #
+#                                                                          #
+# Unless required by applicable law or agreed to in writing, software      #
+# distributed under the License is distributed on an "AS IS" BASIS,        #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. #
+# See the License for the specific language governing permissions and      #
+# limitations under the License.                                           #
+# ------------------------------------------------------------------------ #
+
+import math
+
+import torch
+import torch.nn as nn
+
+
+class ALawCompression(nn.Module):
+    """See `this page <https://sp-nitech.github.io/sptk/latest/main/alaw.html>`_
+    for details.
+
+    Parameters
+    ----------
+    abs_max : float > 0 [scalar]
+        Absolute maximum value of input.
+
+    a : float >= 1 [scalar]
+        Compression factor, :math:`A`.
+
+    """
+
+    def __init__(self, abs_max=1, a=87.6):
+        super(ALawCompression, self).__init__()
+
+        self.abs_max = abs_max
+        self.a = a
+
+        assert 0 < self.abs_max
+        assert 1 <= self.a
+
+        self.const = self.abs_max / (1 + math.log(self.a))
+
+    def forward(self, x):
+        """Compress waveform by A-law algorithm.
+
+        Parameters
+        ----------
+        x : Tensor [shape=(...,)]
+            Waveform.
+
+        Returns
+        -------
+        y : Tensor [shape=(...,)]
+            Compressed waveform.
+
+        Examples
+        --------
+        >>> x = diffsptk.ramp(4)
+        >>> alaw = diffsptk.ALawCompression(4)
+        >>> y = alaw(x)
+        >>> y
+        tensor([0.0000, 2.9868, 3.4934, 3.7897, 4.0000])
+
+        """
+        x_abs = x.abs() / self.abs_max
+        x1 = self.a * x_abs
+        x2 = 1 + torch.log(x1)
+        condition = x_abs < (1 / self.a)
+        y = self.const * torch.sign(x) * torch.where(condition, x1, x2)
+        return y

diffsptk/core/ialaw.py

@@ -0,0 +1,77 @@
+# ------------------------------------------------------------------------ #
+# Copyright 2022 SPTK Working Group                                        #
+#                                                                          #
+# Licensed under the Apache License, Version 2.0 (the "License");          #
+# you may not use this file except in compliance with the License.         #
+# You may obtain a copy of the License at                                  #
+#                                                                          #
+#     http://www.apache.org/licenses/LICENSE-2.0                           #
+#                                                                          #
+# Unless required by applicable law or agreed to in writing, software      #
+# distributed under the License is distributed on an "AS IS" BASIS,        #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. #
+# See the License for the specific language governing permissions and      #
+# limitations under the License.                                           #
+# ------------------------------------------------------------------------ #
+
+import math
+
+import torch
+import torch.nn as nn
+
+
+class ALawExpansion(nn.Module):
+    """See `this page <https://sp-nitech.github.io/sptk/latest/main/ialaw.html>`_
+    for details.
+
+    Parameters
+    ----------
+    abs_max : float > 0 [scalar]
+        Absolute maximum value of input.
+
+    a : float >= 1 [scalar]
+        Compression factor, :math:`A`.
+
+    """
+
+    def __init__(self, abs_max=1, a=87.6):
+        super(ALawExpansion, self).__init__()
+
+        self.abs_max = abs_max
+        self.a = a
+
+        assert 0 < self.abs_max
+        assert 1 <= self.a
+
+        self.const = self.abs_max / self.a
+        self.z = 1 + math.log(self.a)
+
+    def forward(self, y):
+        """Expand waveform by A-law algorithm.
+
+        Parameters
+        ----------
+        y : Tensor [shape=(...,)]
+            Compressed waveform.
+
+        Returns
+        -------
+        x : Tensor [shape=(...,)]
+            Waveform.
+
+        Examples
+        --------
+        >>> x = diffsptk.ramp(4)
+        >>> alaw = diffsptk.ALawCompression(4)
+        >>> ialaw = diffsptk.ALawExpansion(4)
+        >>> x2 = ialaw(alaw(x))
+        >>> x2
+        tensor([0.0000, 1.0000, 2.0000, 3.0000, 4.0000])
+
+        """
+        y_abs = y.abs() / self.abs_max
+        y1 = self.z * y_abs
+        y2 = torch.exp(y1 - 1)
+        condition = y_abs < (1 / self.z)
+        x = self.const * torch.sign(y) * torch.where(condition, y1, y2)
+        return x

diffsptk/core/iulaw.py

@@ -39,7 +39,7 @@ def __init__(self, abs_max=1, mu=255):
         self.mu = mu
 
         assert 0 < self.abs_max
-        assert 0 < self.mu
+        assert 1 <= self.mu
 
         self.const = self.abs_max / self.mu
 
@@ -66,6 +66,6 @@ def forward(self, y):
         tensor([0.0000, 1.0000, 2.0000, 3.0000, 4.0000])
 
         """
-        y2 = y.abs() / self.abs_max
-        x = self.const * torch.sign(y) * (torch.pow(1 + self.mu, y2) - 1)
+        y_abs = y.abs() / self.abs_max
+        x = self.const * torch.sign(y) * (torch.pow(1 + self.mu, y_abs) - 1)
         return x

diffsptk/core/ulaw.py

@@ -41,7 +41,7 @@ def __init__(self, abs_max=1, mu=255):
         self.mu = mu
 
         assert 0 < self.abs_max
-        assert 0 < self.mu
+        assert 1 <= self.mu
 
         self.const = self.abs_max / math.log1p(self.mu)
 
@@ -67,6 +67,6 @@ def forward(self, x):
         tensor([0.0000, 3.0084, 3.5028, 3.7934, 4.0000])
 
         """
-        x2 = x.abs() / self.abs_max
-        y = self.const * torch.sign(x) * torch.log1p(self.mu * x2)
+        x_abs = x.abs() / self.abs_max
+        y = self.const * torch.sign(x) * torch.log1p(self.mu * x_abs)
         return y

docs/core/alaw.rst

@@ -0,0 +1,9 @@
+.. _alaw:
+
+alaw
+----
+
+.. autoclass:: diffsptk.ALawCompression
+   :members:
+
+.. seealso:: :ref:`ialaw`  :ref:`ulaw`

docs/core/ialaw.rst

@@ -0,0 +1,9 @@
+.. _ialaw:
+
+ialaw
+-----
+
+.. autoclass:: diffsptk.ALawExpansion
+   :members:
+
+.. seealso:: :ref:`alaw`  :ref:`iulaw`

tests/test_alaw.py

@@ -0,0 +1,36 @@
+# ------------------------------------------------------------------------ #
+# Copyright 2022 SPTK Working Group                                        #
+#                                                                          #
+# Licensed under the Apache License, Version 2.0 (the "License");          #
+# you may not use this file except in compliance with the License.         #
+# You may obtain a copy of the License at                                  #
+#                                                                          #
+#     http://www.apache.org/licenses/LICENSE-2.0                           #
+#                                                                          #
+# Unless required by applicable law or agreed to in writing, software      #
+# distributed under the License is distributed on an "AS IS" BASIS,        #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. #
+# See the License for the specific language governing permissions and      #
+# limitations under the License.                                           #
+# ------------------------------------------------------------------------ #
+
+import pytest
+
+import diffsptk
+import tests.utils as U
+
+
+@pytest.mark.parametrize("device", ["cpu", "cuda"])
+def test_compatibility(device, v=10, a=80, L=10):
+    alaw = diffsptk.ALawCompression(v, a)
+
+    U.check_compatibility(
+        device,
+        alaw,
+        [],
+        f"ramp -l {L}",
+        f"alaw -v {v} -a {a}",
+        [],
+    )
+
+    U.check_differentiable(device, alaw, [L])

tests/test_ialaw.py

@@ -0,0 +1,36 @@
+# ------------------------------------------------------------------------ #
+# Copyright 2022 SPTK Working Group                                        #
+#                                                                          #
+# Licensed under the Apache License, Version 2.0 (the "License");          #
+# you may not use this file except in compliance with the License.         #
+# You may obtain a copy of the License at                                  #
+#                                                                          #
+#     http://www.apache.org/licenses/LICENSE-2.0                           #
+#                                                                          #
+# Unless required by applicable law or agreed to in writing, software      #
+# distributed under the License is distributed on an "AS IS" BASIS,        #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. #
+# See the License for the specific language governing permissions and      #
+# limitations under the License.                                           #
+# ------------------------------------------------------------------------ #
+
+import pytest
+
+import diffsptk
+import tests.utils as U
+
+
+@pytest.mark.parametrize("device", ["cpu", "cuda"])
+def test_compatibility(device, v=10, a=80, L=10):
+    ialaw = diffsptk.ALawExpansion(v, a)
+
+    U.check_compatibility(
+        device,
+        ialaw,
+        [],
+        f"ramp -l {L}",
+        f"ialaw -v {v} -a {a}",
+        [],
+    )
+
+    U.check_differentiable(device, ialaw, [L])