[ResNet] Refactor resnet from VAE (#65)

src/diffusers/models/resnet.py

@@ -222,9 +222,9 @@ class ResnetBlock(nn.Module):
 
         self.conv1 = torch.nn.Conv2d(in_channels, out_channels, kernel_size=3, stride=1, padding=1)
 
-        if time_embedding_norm == "default":
+        if time_embedding_norm == "default" and temb_channels > 0:
             self.temb_proj = torch.nn.Linear(temb_channels, out_channels)
-        elif time_embedding_norm == "scale_shift":
+        elif time_embedding_norm == "scale_shift" and temb_channels > 0:
             self.temb_proj = torch.nn.Linear(temb_channels, 2 * out_channels)
 
         self.norm2 = Normalize(out_channels, num_groups=groups_out, eps=eps)
@@ -427,7 +427,10 @@ class ResnetBlock(nn.Module):
             h = self.nonlinearity(h)
         h = h * mask
 
+        if temb is not None:
             temb = self.temb_proj(self.nonlinearity(temb))[:, :, None, None]
+        else:
+            temb = 0
 
         if self.time_embedding_norm == "scale_shift":
             scale, shift = torch.chunk(temb, 2, dim=1)

src/diffusers/models/vae.py

-import math
-
 import numpy as np
 import torch
 import torch.nn as nn
@@ -7,26 +5,7 @@ import torch.nn as nn
 from ..configuration_utils import ConfigMixin
 from ..modeling_utils import ModelMixin
 from .attention import AttentionBlock
-from .resnet import Downsample, Upsample
-
-
-def get_timestep_embedding(timesteps, embedding_dim):
-    """
-    This matches the implementation in Denoising Diffusion Probabilistic Models: From Fairseq. Build sinusoidal
-    embeddings. This matches the implementation in tensor2tensor, but differs slightly from the description in Section
-    3.5 of "Attention Is All You Need".
-    """
-    assert len(timesteps.shape) == 1
-
-    half_dim = embedding_dim // 2
-    emb = math.log(10000) / (half_dim - 1)
-    emb = torch.exp(torch.arange(half_dim, dtype=torch.float32) * -emb)
-    emb = emb.to(device=timesteps.device)
-    emb = timesteps.float()[:, None] * emb[None, :]
-    emb = torch.cat([torch.sin(emb), torch.cos(emb)], dim=1)
-    if embedding_dim % 2 == 1:  # zero pad
-        emb = torch.nn.functional.pad(emb, (0, 1, 0, 0))
-    return emb
+from .resnet import Downsample, ResnetBlock, Upsample
 
 
 def nonlinearity(x):
@@ -38,50 +17,6 @@ def Normalize(in_channels):
     return torch.nn.GroupNorm(num_groups=32, num_channels=in_channels, eps=1e-6, affine=True)
 
 
-class ResnetBlock(nn.Module):
-    def __init__(self, *, in_channels, out_channels=None, conv_shortcut=False, dropout, temb_channels=512):
-        super().__init__()
-        self.in_channels = in_channels
-        out_channels = in_channels if out_channels is None else out_channels
-        self.out_channels = out_channels
-        self.use_conv_shortcut = conv_shortcut
-
-        self.norm1 = Normalize(in_channels)
-        self.conv1 = torch.nn.Conv2d(in_channels, out_channels, kernel_size=3, stride=1, padding=1)
-        if temb_channels > 0:
-            self.temb_proj = torch.nn.Linear(temb_channels, out_channels)
-        self.norm2 = Normalize(out_channels)
-        self.dropout = torch.nn.Dropout(dropout)
-        self.conv2 = torch.nn.Conv2d(out_channels, out_channels, kernel_size=3, stride=1, padding=1)
-        if self.in_channels != self.out_channels:
-            if self.use_conv_shortcut:
-                self.conv_shortcut = torch.nn.Conv2d(in_channels, out_channels, kernel_size=3, stride=1, padding=1)
-            else:
-                self.nin_shortcut = torch.nn.Conv2d(in_channels, out_channels, kernel_size=1, stride=1, padding=0)
-
-    def forward(self, x, temb):
-        h = x
-        h = self.norm1(h)
-        h = nonlinearity(h)
-        h = self.conv1(h)
-
-        if temb is not None:
-            h = h + self.temb_proj(nonlinearity(temb))[:, :, None, None]
-
-        h = self.norm2(h)
-        h = nonlinearity(h)
-        h = self.dropout(h)
-        h = self.conv2(h)
-
-        if self.in_channels != self.out_channels:
-            if self.use_conv_shortcut:
-                x = self.conv_shortcut(x)
-            else:
-                x = self.nin_shortcut(x)
-
-        return x + h
-
-
 class Encoder(nn.Module):
     def __init__(
         self,