align tts MDN layer

TTS/tts/layers/align_tts/mdn.py

@@ -0,0 +1,25 @@
+import torch
+from torch import nn
+from ..generic.normalization import LayerNorm
+
+
+class MDNBlock(nn.Module):
+    """Mixture of Density Network implementation
+    https://arxiv.org/pdf/2003.01950.pdf
+    """
+    def __init__(self, in_channels, out_channels):
+        super().__init__()
+        self.out_channels = out_channels
+        self.mdn = nn.Sequential(nn.Conv1d(in_channels, in_channels, 1),
+                                 LayerNorm(in_channels),
+                                 nn.ReLU(),
+                                 nn.Dropout(0.1),
+                                 nn.Conv1d(in_channels, out_channels, 1))
+
+    def forward(self, x):
+        mu_sigma = self.mdn(x)
+        # TODO: check this sigmoid
+        # mu = torch.sigmoid(mu_sigma[:, :self.out_channels//2, :])
+        mu = mu_sigma[:, :self.out_channels//2, :]
+        log_sigma = mu_sigma[:, self.out_channels//2:, :]
+        return mu, log_sigma