1 files changed, 58 insertions, 0 deletions
diff --git a/dnn/torch/lpcnet/utils/ulaw.py b/dnn/torch/lpcnet/utils/ulaw.py
new file mode 100644
index 00000000..05c395e9
--- /dev/null
+++ b/dnn/torch/lpcnet/utils/ulaw.py
@@ -0,0 +1,58 @@
+"""
+/* Copyright (c) 2023 Amazon
+   Written by Jan Buethe */
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+"""
+
+import math as m
+
+import torch
+
+
+
+def ulaw2lin(u):
+    scale_1 = 32768.0 / 255.0
+    u = u - 128
+    s = torch.sign(u)
+    u = torch.abs(u)
+    return s * scale_1 * (torch.exp(u / 128. * m.log(256)) - 1)
+
+
+def lin2ulawq(x):
+    scale = 255.0 / 32768.0
+    s = torch.sign(x)
+    x = torch.abs(x)
+    u = s * (128 * torch.log(1 + scale * x) / m.log(256))
+    u = torch.clip(128 + torch.round(u), 0, 255)
+    return u
+
+def lin2ulaw(x):
+    scale = 255.0 / 32768.0
+    s = torch.sign(x)
+    x = torch.abs(x)
+    u = s * (128 * torch.log(1 + scale * x) / torch.log(256))
+    u = torch.clip(128 + u, 0, 255)
+    return u
+\ No newline at end of file