Add AdaNorm to AdaLN

vall_e/vall_e/base.py

@@ -133,16 +133,27 @@ def forward(self, x, m):
 
 
 class AdaLN(nn.Module):
-    def __init__(self, d_model, n_levels, eps=1e-5):
+    def __init__(self, d_model, n_levels, eps=1e-5, k=0.1, c=2):
         super().__init__()
         self.eps = eps
         self.emb = nn.Embedding(n_levels, d_model * 2)
+        self.k = k
+        self.c = c
         nn.init.zeros_(self.emb.weight)
 
     def forward(self, x, l):
         logγ, β = self.emb(l).unsqueeze(1).chunk(2, dim=-1)
+
         h = F.layer_norm(x, x.shape[-1:], eps=self.eps)
+
+        # The initial implementation (https://github.com/enhuiz/vall-e/blob/fbf023448c08e55c0422eefed7fc234cf8b76680/vall_e/vall_e/base.py#L135)
+        # performed worse than vanilla LayerNorm.
+        # The authors mentioned another AdaNorm paper (https://openreview.net/pdf?id=HyxndNrxLB) as they introduce AdaLN.
+        # Did they use AdaNorm inside AdaLN? (as follows)
+        h = self.c * (1 - (self.k * h).detach()) * h
+
         y = logγ.exp() * h + β
+
         return y