refactor HifiGAN discriminator

TTS/vocoder/models/hifigan_discriminator.py

@@ -204,8 +204,6 @@ class HifiganDiscriminator(nn.Module):
             List[Tensor]: discriminator scores.
             List[List[Tensor]]: list of list of features from each layers of each discriminator.
         """
-        scores, feats = self.msd(x)
-        scores_, feats_ = self.mpd(x)
-        scores += scores_
-        feats += feats_
-        return scores, feats
+        scores, feats = self.mpd(x)
+        scores_, feats_ = self.msd(x)
+        return scores + scores_, feats + feats_

TTS/vocoder/models/hifigan_generator.py

@@ -1,3 +1,4 @@
+# adopted from https://github.com/jik876/hifi-gan/blob/master/models.py
 import torch
 import torch.nn.functional as F
 import torch.nn as nn