PixArt sigma

Mentioned in #19
Also removes old example sampler since updating it would be too much overhead.
Pytorch attention is still wonky.

PixArt/conf.py

@@ -1,40 +1,54 @@
 """
 List of all PixArt model types / settings
 """
+
+sampling_settings = {
+	"beta_schedule" : "sqrt_linear",
+	"linear_start"  : 0.0001,
+	"linear_end"    : 0.02,
+	"timesteps"     : 1000,
+}
+
 pixart_conf = {
 	"PixArtMS_XL_2": { # models/PixArtMS
 		"target": "PixArtMS",
 		"unet_config": {
 			"input_size"  : 1024//8,
-			"lewei_scale" :    2,
 			"depth"       :   28,
 			"num_heads"   :   16,
 			"patch_size"  :    2,
 			"hidden_size" : 1152,
+			"pe_interpolation": 2,
 		},
-		"sampling_settings": {
-			"beta_schedule" : "sqrt_linear",
-			"linear_start"  : 0.0001,
-			"linear_end"    : 0.02,
-			"timesteps"     : 1000,
+		"sampling_settings" : sampling_settings,
+	},
+	"PixArtMS_Sigma_XL_2": {
+		"target": "PixArtMSSigma",
+		"unet_config": {
+			"input_size"  : 1024//8,
+			"token_num"   :  300,
+			"depth"       :   28,
+			"num_heads"   :   16,
+			"patch_size"  :    2,
+			"hidden_size" : 1152,
+			"micro_condition": False,
+			"pe_interpolation": 2,
+			"model_max_length": 300,
 		},
+		"sampling_settings" : sampling_settings,
 	},
 	"PixArt_XL_2": { # models/PixArt
 		"target": "PixArt",
 		"unet_config": {
 			"input_size"  :  512//8,
-			"lewei_scale" :    1,
+			"token_num"   :  120,
 			"depth"       :   28,
 			"num_heads"   :   16,
 			"patch_size"  :    2,
 			"hidden_size" : 1152,
+			"pe_interpolation": 1,
 		},
-		"sampling_settings": {
-			"beta_schedule" : "sqrt_linear",
-			"linear_start"  : 0.0001,
-			"linear_end"    : 0.02,
-			"timesteps"     : 1000,
-		},
+		"sampling_settings" : sampling_settings,
 	},
 }
 
@@ -77,3 +91,7 @@ pixart_res = {
 		'3.62': [928, 256], '3.75': [960, 256], '3.88': [992, 256], '4.00': [1024,256]
 	},
 }
+# These should be the same
+pixart_res.update({
+	"PixArtMS_Sigma_XL_2_512": pixart_res["PixArt_XL_2"],
+})

PixArt/loader.py

@@ -82,6 +82,10 @@ def load_pixart(model_path, model_conf):
 	elif model_conf.model_target == "PixArt":
 		from .models.PixArt import PixArt
 		model.diffusion_model = PixArt(**model_conf.unet_config)
+	elif model_conf.model_target == "PixArtMSSigma":
+		from .models.PixArtMS import PixArtMS
+		model.diffusion_model = PixArtMS(**model_conf.unet_config)
+		model.latent_format = comfy.latent_formats.SDXL()
 	elif model_conf.model_target == "ControlPixArtMSHalf":
 		from .models.PixArtMS import PixArtMS
 		from .models.pixart_controlnet import ControlPixArtMSHalf

PixArt/models/PixArt.py

@@ -18,31 +18,31 @@ from timm.models.vision_transformer import PatchEmbed, Mlp
 
 
 from .utils import auto_grad_checkpoint, to_2tuple
-from .PixArt_blocks import t2i_modulate, CaptionEmbedder, WindowAttention, MultiHeadCrossAttention, T2IFinalLayer, TimestepEmbedder, LabelEmbedder, FinalLayer
+from .PixArt_blocks import t2i_modulate, CaptionEmbedder, AttentionKVCompress, MultiHeadCrossAttention, T2IFinalLayer, TimestepEmbedder, LabelEmbedder, FinalLayer
 
 
 class PixArtBlock(nn.Module):
     """
     A PixArt block with adaptive layer norm (adaLN-single) conditioning.
     """
-
-    def __init__(self, hidden_size, num_heads, mlp_ratio=4.0, drop_path=0., window_size=0, input_size=None, use_rel_pos=False, **block_kwargs):
+    def __init__(self, hidden_size, num_heads, mlp_ratio=4.0, drop_path=0, input_size=None, sampling=None, sr_ratio=1, qk_norm=False, **block_kwargs):
         super().__init__()
-        self.hidden_size = hidden_size
         self.norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
-        self.attn = WindowAttention(hidden_size, num_heads=num_heads, qkv_bias=True,
-                                    input_size=input_size if window_size == 0 else (window_size, window_size),
-                                    use_rel_pos=use_rel_pos, **block_kwargs)
+        self.attn = AttentionKVCompress(
+            hidden_size, num_heads=num_heads, qkv_bias=True, sampling=sampling, sr_ratio=sr_ratio,
+            qk_norm=qk_norm, **block_kwargs
+        )
         self.cross_attn = MultiHeadCrossAttention(hidden_size, num_heads, **block_kwargs)
         self.norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
         # to be compatible with lower version pytorch
         approx_gelu = lambda: nn.GELU(approximate="tanh")
         self.mlp = Mlp(in_features=hidden_size, hidden_features=int(hidden_size * mlp_ratio), act_layer=approx_gelu, drop=0)
         self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
-        self.window_size = window_size
         self.scale_shift_table = nn.Parameter(torch.randn(6, hidden_size) / hidden_size ** 0.5)
+        self.sampling = sampling
+        self.sr_ratio = sr_ratio
 
-    def forward(self, x, y, t, mask=None):
+    def forward(self, x, y, t, mask=None, **kwargs):
         B, N, C = x.shape
 
         shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = (self.scale_shift_table[None] + t.reshape(B, 6, -1)).chunk(6, dim=1)
@@ -53,14 +53,11 @@ class PixArtBlock(nn.Module):
         return x
 
 
-#############################################################################
-#                                 Core PixArt Model                                #
-#################################################################################
+### Core PixArt Model ###
 class PixArt(nn.Module):
     """
     Diffusion model with a Transformer backbone.
     """
-
     def __init__(
             self,
             input_size=32,
@@ -73,12 +70,12 @@ class PixArt(nn.Module):
             class_dropout_prob=0.1,
             pred_sigma=True,
             drop_path: float = 0.,
-            window_size=0,
-            window_block_indexes=[],
-            use_rel_pos=False,
             caption_channels=4096,
-            lewei_scale=1.0,
+            pe_interpolation=1.0,
             config=None,
+            model_max_length=120,
+            qk_norm=False,
+            kv_compress_config=None,
             **kwargs,
     ):
         super().__init__()
@@ -87,8 +84,8 @@ class PixArt(nn.Module):
         self.out_channels = in_channels * 2 if pred_sigma else in_channels
         self.patch_size = patch_size
         self.num_heads = num_heads
-        self.lewei_scale = lewei_scale,
-        self.dtype = torch.get_default_dtype()
+        self.pe_interpolation = pe_interpolation
+        self.depth = depth
 
         self.x_embedder = PatchEmbed(input_size, patch_size, in_channels, hidden_size, bias=True)
         self.t_embedder = TimestepEmbedder(hidden_size)
@@ -102,21 +99,32 @@ class PixArt(nn.Module):
             nn.SiLU(),
             nn.Linear(hidden_size, 6 * hidden_size, bias=True)
         )
-        self.y_embedder = CaptionEmbedder(in_channels=caption_channels, hidden_size=hidden_size, uncond_prob=class_dropout_prob, act_layer=approx_gelu)
+        self.y_embedder = CaptionEmbedder(
+            in_channels=caption_channels, hidden_size=hidden_size, uncond_prob=class_dropout_prob,
+            act_layer=approx_gelu, token_num=model_max_length
+		)
         drop_path = [x.item() for x in torch.linspace(0, drop_path, depth)]  # stochastic depth decay rule
+        self.kv_compress_config = kv_compress_config
+        if kv_compress_config is None:
+            self.kv_compress_config = {
+                'sampling': None,
+                'scale_factor': 1,
+                'kv_compress_layer': [],
+            }
         self.blocks = nn.ModuleList([
-            PixArtBlock(hidden_size, num_heads, mlp_ratio=mlp_ratio, drop_path=drop_path[i],
-                          input_size=(input_size // patch_size, input_size // patch_size),
-                          window_size=window_size if i in window_block_indexes else 0,
-                          use_rel_pos=use_rel_pos if i in window_block_indexes else False)
+            PixArtBlock(
+                hidden_size, num_heads, mlp_ratio=mlp_ratio, drop_path=drop_path[i],
+                input_size=(input_size // patch_size, input_size // patch_size),
+                sampling=self.kv_compress_config['sampling'],
+                sr_ratio=int(
+                    self.kv_compress_config['scale_factor']
+                ) if i in self.kv_compress_config['kv_compress_layer'] else 1,
+                qk_norm=qk_norm,
+            )
             for i in range(depth)
         ])
         self.final_layer = T2IFinalLayer(hidden_size, patch_size, self.out_channels)
 
-        self.initialize_weights()
-
-        print(f'Warning: lewei scale: {self.lewei_scale}, base size: {self.base_size}')
-
     def forward_raw(self, x, t, y, mask=None, data_info=None):
         """
         Original forward pass of PixArt.
@@ -124,9 +132,13 @@ class PixArt(nn.Module):
         t: (N,) tensor of diffusion timesteps
         y: (N, 1, 120, C) tensor of class labels
         """
+        x = x.to(self.dtype)
+        timestep = t.to(self.dtype)
+        y = y.to(self.dtype)
+        pos_embed = self.pos_embed.to(self.dtype)
         self.h, self.w = x.shape[-2]//self.patch_size, x.shape[-1]//self.patch_size
-        x = self.x_embedder(x) + self.pos_embed  # (N, T, D), where T = H * W / patch_size ** 2
-        t = self.t_embedder(t)  # (N, D)
+        x = self.x_embedder(x) + pos_embed  # (N, T, D), where T = H * W / patch_size ** 2
+        t = self.t_embedder(timestep.to(x.dtype))  # (N, D)
         t0 = self.t_block(t)
         y = self.y_embedder(y, self.training)  # (N, 1, L, D)
         if mask is not None:
@@ -168,29 +180,6 @@ class PixArt(nn.Module):
         eps, rest = out[:, :self.in_channels], out[:, self.in_channels:]
         return eps
 
-    def forward_with_dpmsolver(self, x, t, y, mask=None, **kwargs):
-        """
-        dpm solver donnot need variance prediction
-        """
-        # https://github.com/openai/glide-text2im/blob/main/notebooks/text2im.ipynb
-        model_out = self.forward(x, t, y, mask)
-        return model_out.chunk(2, dim=1)[0]
-
-    def forward_with_cfg(self, x, t, y, cfg_scale, **kwargs):
-        """
-        Forward pass of PixArt, but also batches the unconditional forward pass for classifier-free guidance.
-        """
-        # https://github.com/openai/glide-text2im/blob/main/notebooks/text2im.ipynb
-        half = x[: len(x) // 2]
-        combined = torch.cat([half, half], dim=0)
-        model_out = self.forward(combined, t, y, kwargs)
-        model_out = model_out['x'] if isinstance(model_out, dict) else model_out
-        eps, rest = model_out[:, :3], model_out[:, 3:]
-        cond_eps, uncond_eps = torch.split(eps, len(eps) // 2, dim=0)
-        half_eps = uncond_eps + cfg_scale * (cond_eps - uncond_eps)
-        eps = torch.cat([half_eps, half_eps], dim=0)
-        return torch.cat([eps, rest], dim=1)
-
     def unpatchify(self, x):
         """
         x: (N, T, patch_size**2 * C)
@@ -206,44 +195,8 @@ class PixArt(nn.Module):
         imgs = x.reshape(shape=(x.shape[0], c, h * p, h * p))
         return imgs
 
-    def initialize_weights(self):
-        # Initialize transformer layers:
-        def _basic_init(module):
-            if isinstance(module, nn.Linear):
-                torch.nn.init.xavier_uniform_(module.weight)
-                if module.bias is not None:
-                    nn.init.constant_(module.bias, 0)
 
-        self.apply(_basic_init)
-
-        # Initialize (and freeze) pos_embed by sin-cos embedding:
-        pos_embed = get_2d_sincos_pos_embed(self.pos_embed.shape[-1], int(self.x_embedder.num_patches ** 0.5), lewei_scale=self.lewei_scale, base_size=self.base_size)
-        self.pos_embed.data.copy_(torch.from_numpy(pos_embed).unsqueeze(0).to(self.dtype))
-
-        # Initialize patch_embed like nn.Linear (instead of nn.Conv2d):
-        w = self.x_embedder.proj.weight.data
-        nn.init.xavier_uniform_(w.view([w.shape[0], -1]))
-
-        # Initialize timestep embedding MLP:
-        nn.init.normal_(self.t_embedder.mlp[0].weight, std=0.02)
-        nn.init.normal_(self.t_embedder.mlp[2].weight, std=0.02)
-        nn.init.normal_(self.t_block[1].weight, std=0.02)
-
-        # Initialize caption embedding MLP:
-        nn.init.normal_(self.y_embedder.y_proj.fc1.weight, std=0.02)
-        nn.init.normal_(self.y_embedder.y_proj.fc2.weight, std=0.02)
-
-        # Zero-out adaLN modulation layers in PixArt blocks:
-        for block in self.blocks:
-            nn.init.constant_(block.cross_attn.proj.weight, 0)
-            nn.init.constant_(block.cross_attn.proj.bias, 0)
-
-        # Zero-out output layers:
-        nn.init.constant_(self.final_layer.linear.weight, 0)
-        nn.init.constant_(self.final_layer.linear.bias, 0)
-
-
-def get_2d_sincos_pos_embed(embed_dim, grid_size, cls_token=False, extra_tokens=0, lewei_scale=1.0, base_size=16):
+def get_2d_sincos_pos_embed(embed_dim, grid_size, cls_token=False, extra_tokens=0, pe_interpolation=1.0, base_size=16):
     """
     grid_size: int of the grid height and width
     return:
@@ -251,8 +204,8 @@ def get_2d_sincos_pos_embed(embed_dim, grid_size, cls_token=False, extra_tokens=
     """
     if isinstance(grid_size, int):
         grid_size = to_2tuple(grid_size)
-    grid_h = np.arange(grid_size[0], dtype=np.float32) / (grid_size[0]/base_size) / lewei_scale
-    grid_w = np.arange(grid_size[1], dtype=np.float32) / (grid_size[1]/base_size) / lewei_scale
+    grid_h = np.arange(grid_size[0], dtype=np.float32) / (grid_size[0]/base_size) / pe_interpolation
+    grid_w = np.arange(grid_size[1], dtype=np.float32) / (grid_size[1]/base_size) / pe_interpolation
     grid = np.meshgrid(grid_w, grid_h)  # here w goes first
     grid = np.stack(grid, axis=0)
     grid = grid.reshape([2, 1, grid_size[1], grid_size[0]])

PixArt/models/PixArtMS.py

@@ -15,12 +15,13 @@ from timm.models.layers import DropPath
 from timm.models.vision_transformer import Mlp
 
 from .utils import auto_grad_checkpoint, to_2tuple
-from .PixArt_blocks import t2i_modulate, CaptionEmbedder, WindowAttention, MultiHeadCrossAttention, T2IFinalLayer, TimestepEmbedder, SizeEmbedder
+from .PixArt_blocks import t2i_modulate, CaptionEmbedder, AttentionKVCompress, MultiHeadCrossAttention, T2IFinalLayer, TimestepEmbedder, SizeEmbedder
 from .PixArt import PixArt, get_2d_sincos_pos_embed
 
 
 class PatchEmbed(nn.Module):
-    """ 2D Image to Patch Embedding
+    """
+    2D Image to Patch Embedding
     """
     def __init__(
             self,
@@ -50,42 +51,39 @@ class PixArtMSBlock(nn.Module):
     """
     A PixArt block with adaptive layer norm zero (adaLN-Zero) conditioning.
     """
-
-    def __init__(self, hidden_size, num_heads, mlp_ratio=4.0, drop_path=0., window_size=0, input_size=None, use_rel_pos=False, **block_kwargs):
+    def __init__(self, hidden_size, num_heads, mlp_ratio=4.0, drop_path=0., input_size=None,
+                 sampling=None, sr_ratio=1, qk_norm=False, **block_kwargs):
         super().__init__()
         self.hidden_size = hidden_size
         self.norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
-        self.attn = WindowAttention(hidden_size, num_heads=num_heads, qkv_bias=True,
-                              input_size=input_size if window_size == 0 else (window_size, window_size),
-                              use_rel_pos=use_rel_pos, **block_kwargs)
+        self.attn = AttentionKVCompress(
+            hidden_size, num_heads=num_heads, qkv_bias=True, sampling=sampling, sr_ratio=sr_ratio,
+            qk_norm=qk_norm, **block_kwargs
+        )
         self.cross_attn = MultiHeadCrossAttention(hidden_size, num_heads, **block_kwargs)
         self.norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
         # to be compatible with lower version pytorch
         approx_gelu = lambda: nn.GELU(approximate="tanh")
         self.mlp = Mlp(in_features=hidden_size, hidden_features=int(hidden_size * mlp_ratio), act_layer=approx_gelu, drop=0)
         self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
-        self.window_size = window_size
         self.scale_shift_table = nn.Parameter(torch.randn(6, hidden_size) / hidden_size ** 0.5)
 
-    def forward(self, x, y, t, mask=None, **kwargs):
+    def forward(self, x, y, t, mask=None, HW=None, **kwargs):
         B, N, C = x.shape
 
         shift_msa, scale_msa, gate_msa, shift_mlp, scale_mlp, gate_mlp = (self.scale_shift_table[None] + t.reshape(B, 6, -1)).chunk(6, dim=1)
-        x = x + self.drop_path(gate_msa * self.attn(t2i_modulate(self.norm1(x), shift_msa, scale_msa)))
+        x = x + self.drop_path(gate_msa * self.attn(t2i_modulate(self.norm1(x), shift_msa, scale_msa), HW=HW))
         x = x + self.cross_attn(x, y, mask)
         x = x + self.drop_path(gate_mlp * self.mlp(t2i_modulate(self.norm2(x), shift_mlp, scale_mlp)))
 
         return x
 
 
-#############################################################################
-#                                 Core PixArt Model                                #
-#################################################################################
+### Core PixArt Model ###
 class PixArtMS(PixArt):
     """
     Diffusion model with a Transformer backbone.
     """
-
     def __init__(
             self,
             input_size=32,
@@ -99,12 +97,13 @@ class PixArtMS(PixArt):
             learn_sigma=True,
             pred_sigma=True,
             drop_path: float = 0.,
-            window_size=0,
-            window_block_indexes=[],
-            use_rel_pos=False,
             caption_channels=4096,
-            lewei_scale=1.,
+            pe_interpolation=1.,
             config=None,
+            model_max_length=120,
+            micro_condition=True,
+            qk_norm=False,
+            kv_compress_config=None,
             **kwargs,
     ):
         super().__init__(
@@ -119,11 +118,11 @@ class PixArtMS(PixArt):
             learn_sigma=learn_sigma,
             pred_sigma=pred_sigma,
             drop_path=drop_path,
-            window_size=window_size,
-            window_block_indexes=window_block_indexes,
-            use_rel_pos=use_rel_pos,
-            lewei_scale=lewei_scale,
+            pe_interpolation=pe_interpolation,
             config=config,
+            model_max_length=model_max_length,
+            qk_norm=qk_norm,
+            kv_compress_config=kv_compress_config,
             **kwargs,
         )
         self.dtype = torch.get_default_dtype()
@@ -134,20 +133,29 @@ class PixArtMS(PixArt):
             nn.Linear(hidden_size, 6 * hidden_size, bias=True)
         )
         self.x_embedder = PatchEmbed(patch_size, in_channels, hidden_size, bias=True)
-        self.y_embedder = CaptionEmbedder(in_channels=caption_channels, hidden_size=hidden_size, uncond_prob=class_dropout_prob, act_layer=approx_gelu)
-        self.csize_embedder = SizeEmbedder(hidden_size//3)  # c_size embed
-        self.ar_embedder = SizeEmbedder(hidden_size//3)     # aspect ratio embed
+        self.y_embedder = CaptionEmbedder(in_channels=caption_channels, hidden_size=hidden_size, uncond_prob=class_dropout_prob, act_layer=approx_gelu, token_num=model_max_length)
+        self.micro_conditioning = micro_condition
+        if self.micro_conditioning:
+            self.csize_embedder = SizeEmbedder(hidden_size//3)  # c_size embed
+            self.ar_embedder = SizeEmbedder(hidden_size//3)     # aspect ratio embed
         drop_path = [x.item() for x in torch.linspace(0, drop_path, depth)]  # stochastic depth decay rule
+        if kv_compress_config is None:
+            kv_compress_config = {
+                'sampling': None,
+                'scale_factor': 1,
+                'kv_compress_layer': [],
+            }
         self.blocks = nn.ModuleList([
-            PixArtMSBlock(hidden_size, num_heads, mlp_ratio=mlp_ratio, drop_path=drop_path[i],
-                          input_size=(input_size // patch_size, input_size // patch_size),
-                          window_size=window_size if i in window_block_indexes else 0,
-                          use_rel_pos=use_rel_pos if i in window_block_indexes else False)
+            PixArtMSBlock(
+                hidden_size, num_heads, mlp_ratio=mlp_ratio, drop_path=drop_path[i],
+                input_size=(input_size // patch_size, input_size // patch_size),
+                sampling=kv_compress_config['sampling'],
+                sr_ratio=int(kv_compress_config['scale_factor']) if i in kv_compress_config['kv_compress_layer'] else 1,
+                qk_norm=qk_norm,
+            )
             for i in range(depth)
         ])
         self.final_layer = T2IFinalLayer(hidden_size, patch_size, self.out_channels)
-        self.training = False
-        self.initialize()
 
     def forward_raw(self, x, t, y, mask=None, data_info=None, **kwargs):
         """
@@ -157,16 +165,29 @@ class PixArtMS(PixArt):
         y: (N, 1, 120, C) tensor of class labels
         """
         bs = x.shape[0]
-        c_size, ar = data_info['img_hw'], data_info['aspect_ratio']
+        x = x.to(self.dtype)
+        timestep = t.to(self.dtype)
+        y = y.to(self.dtype)
         self.h, self.w = x.shape[-2]//self.patch_size, x.shape[-1]//self.patch_size
-        pos_embed = torch.from_numpy(get_2d_sincos_pos_embed(self.pos_embed.shape[-1], (self.h, self.w), lewei_scale=self.lewei_scale, base_size=self.base_size)).unsqueeze(0).to(x.device).to(self.dtype)
+        pos_embed = torch.from_numpy(
+            get_2d_sincos_pos_embed(
+                self.pos_embed.shape[-1], (self.h, self.w), pe_interpolation=self.pe_interpolation,
+                base_size=self.base_size
+            )
+        ).unsqueeze(0).to(x.device).to(self.dtype)
+
         x = self.x_embedder(x) + pos_embed  # (N, T, D), where T = H * W / patch_size ** 2
-        t = self.t_embedder(t)  # (N, D)
-        csize = self.csize_embedder(c_size, bs)  # (N, D)
-        ar = self.ar_embedder(ar, bs)  # (N, D)
-        t = t + torch.cat([csize, ar], dim=1)
+        t = self.t_embedder(timestep)  # (N, D)
+
+        if self.micro_conditioning:
+            c_size, ar = data_info['img_hw'].to(self.dtype), data_info['aspect_ratio'].to(self.dtype)
+            csize = self.csize_embedder(c_size, bs)  # (N, D)
+            ar = self.ar_embedder(ar, bs)  # (N, D)
+            t = t + torch.cat([csize, ar], dim=1)
+
         t0 = self.t_block(t)
         y = self.y_embedder(y, self.training)  # (N, D)
+
         if mask is not None:
             if mask.shape[0] != y.shape[0]:
                 mask = mask.repeat(y.shape[0] // mask.shape[0], 1)
@@ -177,9 +198,11 @@ class PixArtMS(PixArt):
             y_lens = [y.shape[2]] * y.shape[0]
             y = y.squeeze(1).view(1, -1, x.shape[-1])
         for block in self.blocks:
-            x = auto_grad_checkpoint(block, x, y, t0, y_lens, **kwargs)  # (N, T, D) #support grad checkpoint
+            x = auto_grad_checkpoint(block, x, y, t0, y_lens, (self.h, self.w), **kwargs)  # (N, T, D) #support grad checkpoint
+
         x = self.final_layer(x, t)  # (N, T, patch_size ** 2 * out_channels)
         x = self.unpatchify(x)  # (N, out_channels, H, W)
+        
         return x
 
     def forward(self, x, timesteps, context, img_hw=None, aspect_ratio=None, **kwargs):
@@ -228,28 +251,6 @@ class PixArtMS(PixArt):
         eps, rest = out[:, :self.in_channels], out[:, self.in_channels:]
         return eps
 
-    def forward_with_dpmsolver(self, x, t, y, data_info, **kwargs):
-        """
-        dpm solver donnot need variance prediction
-        """
-        # https://github.com/openai/glide-text2im/blob/main/notebooks/text2im.ipynb
-        model_out = self.forward_raw(x, t, y, data_info=data_info, **kwargs)
-        return model_out.chunk(2, dim=1)[0]
-
-    def forward_with_cfg(self, x, t, y, cfg_scale, data_info, **kwargs):
-        """
-        Forward pass of PixArt, but also batches the unconditional forward pass for classifier-free guidance.
-        """
-        # https://github.com/openai/glide-text2im/blob/main/notebooks/text2im.ipynb
-        half = x[: len(x) // 2]
-        combined = torch.cat([half, half], dim=0)
-        model_out = self.forward_raw(combined, t, y, data_info=data_info)
-        eps, rest = model_out[:, :3], model_out[:, 3:]
-        cond_eps, uncond_eps = torch.split(eps, len(eps) // 2, dim=0)
-        half_eps = uncond_eps + cfg_scale * (cond_eps - uncond_eps)
-        eps = torch.cat([half_eps, half_eps], dim=0)
-        return torch.cat([eps, rest], dim=1)
-
     def unpatchify(self, x):
         """
         x: (N, T, patch_size**2 * C)
@@ -263,39 +264,3 @@ class PixArtMS(PixArt):
         x = torch.einsum('nhwpqc->nchpwq', x)
         imgs = x.reshape(shape=(x.shape[0], c, self.h * p, self.w * p))
         return imgs
-
-    def initialize(self):
-        # Initialize transformer layers:
-        def _basic_init(module):
-            if isinstance(module, nn.Linear):
-                torch.nn.init.xavier_uniform_(module.weight)
-                if module.bias is not None:
-                    nn.init.constant_(module.bias, 0)
-
-        self.apply(_basic_init)
-
-        # Initialize patch_embed like nn.Linear (instead of nn.Conv2d):
-        w = self.x_embedder.proj.weight.data
-        nn.init.xavier_uniform_(w.view([w.shape[0], -1]))
-
-        # Initialize timestep embedding MLP:
-        nn.init.normal_(self.t_embedder.mlp[0].weight, std=0.02)
-        nn.init.normal_(self.t_embedder.mlp[2].weight, std=0.02)
-        nn.init.normal_(self.t_block[1].weight, std=0.02)
-        nn.init.normal_(self.csize_embedder.mlp[0].weight, std=0.02)
-        nn.init.normal_(self.csize_embedder.mlp[2].weight, std=0.02)
-        nn.init.normal_(self.ar_embedder.mlp[0].weight, std=0.02)
-        nn.init.normal_(self.ar_embedder.mlp[2].weight, std=0.02)
-
-        # Initialize caption embedding MLP:
-        nn.init.normal_(self.y_embedder.y_proj.fc1.weight, std=0.02)
-        nn.init.normal_(self.y_embedder.y_proj.fc2.weight, std=0.02)
-
-        # Zero-out adaLN modulation layers in PixArt blocks:
-        for block in self.blocks:
-            nn.init.constant_(block.cross_attn.proj.weight, 0)
-            nn.init.constant_(block.cross_attn.proj.bias, 0)
-
-        # Zero-out output layers:
-        nn.init.constant_(self.final_layer.linear.weight, 0)
-        nn.init.constant_(self.final_layer.linear.bias, 0)

PixArt/models/PixArt_blocks.py

@@ -11,25 +11,29 @@
 import math
 import torch
 import torch.nn as nn
+import torch.nn.functional as F
 from timm.models.vision_transformer import Mlp, Attention as Attention_
-from einops import rearrange, repeat
+from einops import rearrange
 
-from .utils import add_decomposed_rel_pos
 from comfy import model_management
-
 if model_management.xformers_enabled():
     import xformers
     import xformers.ops
+else:
+    print("""
+########################################
+ PixArt: Not using xformers!
+  Expect images to be non-deterministic!
+  Batch sizes > 1 are most likely broken
+########################################
+""")
 
 def modulate(x, shift, scale):
     return x * (1 + scale.unsqueeze(1)) + shift.unsqueeze(1)
 
-
 def t2i_modulate(x, shift, scale):
     return x * (1 + scale) + shift
 
-competent_attention_implementation = False
-
 class MultiHeadCrossAttention(nn.Module):
     def __init__(self, d_model, num_heads, attn_drop=0., proj_drop=0., **block_kwargs):
         super(MultiHeadCrossAttention, self).__init__()
@@ -49,32 +53,24 @@ class MultiHeadCrossAttention(nn.Module):
         # query/value: img tokens; key: condition; mask: if padding tokens
         B, N, C = x.shape
 
+        q = self.q_linear(x).view(1, -1, self.num_heads, self.head_dim)
+        kv = self.kv_linear(cond).view(1, -1, 2, self.num_heads, self.head_dim)
+        k, v = kv.unbind(2)
+
         if model_management.xformers_enabled():
-            q = self.q_linear(x).view(1, -1, self.num_heads, self.head_dim)
-            kv = self.kv_linear(cond).view(1, -1, 2, self.num_heads, self.head_dim)
-            k, v = kv.unbind(2)
             attn_bias = None
             if mask is not None:
                 attn_bias = xformers.ops.fmha.BlockDiagonalMask.from_seqlens([N] * B, mask)
-            x = xformers.ops.memory_efficient_attention(q, k, v, p=self.attn_drop.p, attn_bias=attn_bias)
-            x = x.view(B, -1, C)
-            x = self.proj(x)
-            x = self.proj_drop(x)
-            return x
+            x = xformers.ops.memory_efficient_attention(
+                q, k, v,
+                p=self.attn_drop.p,
+                attn_bias=attn_bias
+            )
         else:
-            global competent_attention_implementation
-            if not competent_attention_implementation:
-                print("""\nYou should REALLY consider installing/enabling xformers.\nAlternatively, open up ExtraModels/PixArt/models/PixArt_blocks.py and\n- Fix the attention map on line 77 if you know how to\n- Add scaled_dot_product_attention on line 150\n- Send a PR and remove this message on line 32/66-69\n""")
-                competent_attention_implementation = True
-
-            q = self.q_linear(x).view(1, -1, self.num_heads, self.head_dim)
-            kv = self.kv_linear(cond).view(1, -1, 2, self.num_heads, self.head_dim)
-            k, v = kv.unbind(2)
             q, k, v = map(lambda t: t.permute(0, 2, 1, 3),(q, k, v),)
-            
             attn_mask = None
             if mask is not None and len(mask) > 1:
-                # This is probably wrong
+                # This is most definitely wrong, especially for B>1
                 attn_mask = torch.zeros(
                     [1, q.shape[1], q.shape[2], v.shape[2]],
                     dtype=q.dtype,
@@ -82,26 +78,28 @@ class MultiHeadCrossAttention(nn.Module):
                 )
                 attn_mask[:, :, (q.shape[2]//2):, mask[0]:] = True
                 attn_mask[:, :, :(q.shape[2]//2), :mask[1]] = True
-
-            x = torch.nn.functional.scaled_dot_product_attention(q, k, v, attn_mask=attn_mask, dropout_p=self.attn_drop.p)
-            x = x.permute(0, 2, 1, 3).contiguous()
-            x = x.view(B, -1, C)
-            x = self.proj(x)
-            x = self.proj_drop(x)
-            return x
+            x = torch.nn.functional.scaled_dot_product_attention(
+                q, k, v,
+                attn_mask=attn_mask,
+                dropout_p=self.attn_drop.p
+            ).permute(0, 2, 1, 3).contiguous()
+        x = x.view(B, -1, C)
+        x = self.proj(x)
+        x = self.proj_drop(x)
+        return x
 
 
-class WindowAttention(Attention_):
-    """Multi-head Attention block with relative position embeddings."""
+class AttentionKVCompress(Attention_):
+    """Multi-head Attention block with KV token compression and qk norm."""
 
     def __init__(
         self,
         dim,
         num_heads=8,
         qkv_bias=True,
-        use_rel_pos=False,
-        rel_pos_zero_init=True,
-        input_size=None,
+        sampling='conv',
+        sr_ratio=1,
+        qk_norm=False,
         **block_kwargs,
     ):
         """
@@ -109,56 +107,94 @@ class WindowAttention(Attention_):
             dim (int): Number of input channels.
             num_heads (int): Number of attention heads.
             qkv_bias (bool:  If True, add a learnable bias to query, key, value.
-            rel_pos (bool): If True, add relative positional embeddings to the attention map.
-            rel_pos_zero_init (bool): If True, zero initialize relative positional parameters.
-            input_size (int or None): Input resolution for calculating the relative positional
-                parameter size.
         """
         super().__init__(dim, num_heads=num_heads, qkv_bias=qkv_bias, **block_kwargs)
 
-        self.use_rel_pos = use_rel_pos
-        if self.use_rel_pos:
-            # initialize relative positional embeddings
-            self.rel_pos_h = nn.Parameter(torch.zeros(2 * input_size[0] - 1, self.head_dim))
-            self.rel_pos_w = nn.Parameter(torch.zeros(2 * input_size[1] - 1, self.head_dim))
-
-            if not rel_pos_zero_init:
-                nn.init.trunc_normal_(self.rel_pos_h, std=0.02)
-                nn.init.trunc_normal_(self.rel_pos_w, std=0.02)
-
-    def forward(self, x, mask=None):
-        B, N, C = x.shape # 2 4096 1152
-        qkv = self.qkv(x).reshape(B, N, 3, self.num_heads, C // self.num_heads)
-
-        if model_management.xformers_enabled():
-            q, k, v = qkv.unbind(2)
-
-            if getattr(self, 'fp32_attention', False):
-                q, k, v = q.float(), k.float(), v.float()
-
-            attn_bias = None
-            if mask is not None:
-                attn_bias = torch.zeros([B * self.num_heads, q.shape[1], k.shape[1]], dtype=q.dtype, device=q.device)
-                attn_bias.masked_fill_(mask.squeeze(1).repeat(self.num_heads, 1, 1) == 0, float('-inf'))
-            # Switch between torch / xformers attention
-            x = xformers.ops.memory_efficient_attention(q, k, v, p=self.attn_drop.p, attn_bias=attn_bias)
-            x = x.view(B, N, C)
-            x = self.proj(x)
-            x = self.proj_drop(x)
-            return x
+        self.sampling=sampling    # ['conv', 'ave', 'uniform', 'uniform_every']
+        self.sr_ratio = sr_ratio
+        if sr_ratio > 1 and sampling == 'conv':
+            # Avg Conv Init.
+            self.sr = nn.Conv2d(dim, dim, groups=dim, kernel_size=sr_ratio, stride=sr_ratio)
+            self.sr.weight.data.fill_(1/sr_ratio**2)
+            self.sr.bias.data.zero_()
+            self.norm = nn.LayerNorm(dim)
+        if qk_norm:
+            self.q_norm = nn.LayerNorm(dim)
+            self.k_norm = nn.LayerNorm(dim)
         else:
-            q, k, v = qkv.permute(2, 0, 3, 1, 4).unbind(0)
+            self.q_norm = nn.Identity()
+            self.k_norm = nn.Identity()
 
-            q = q * self.scale
-            attn = q @ k.transpose(-2, -1)
-            attn = attn.softmax(dim=-1)
-            attn = self.attn_drop(attn)
-            x = attn @ v
+    def downsample_2d(self, tensor, H, W, scale_factor, sampling=None):
+        if sampling is None or scale_factor == 1:
+            return tensor
+        B, N, C = tensor.shape
 
-            x = x.transpose(1, 2).reshape(B, N, C)
-            x = self.proj(x)
-            x = self.proj_drop(x)
-            return x
+        if sampling == 'uniform_every':
+            return tensor[:, ::scale_factor], int(N // scale_factor)
+
+        tensor = tensor.reshape(B, H, W, C).permute(0, 3, 1, 2)
+        new_H, new_W = int(H / scale_factor), int(W / scale_factor)
+        new_N = new_H * new_W
+
+        if sampling == 'ave':
+            tensor = F.interpolate(
+                tensor, scale_factor=1 / scale_factor, mode='nearest'
+            ).permute(0, 2, 3, 1)
+        elif sampling == 'uniform':
+            tensor = tensor[:, :, ::scale_factor, ::scale_factor].permute(0, 2, 3, 1)
+        elif sampling == 'conv':
+            tensor = self.sr(tensor).reshape(B, C, -1).permute(0, 2, 1)
+            tensor = self.norm(tensor)
+        else:
+            raise ValueError
+
+        return tensor.reshape(B, new_N, C).contiguous(), new_N
+
+    def forward(self, x, mask=None, HW=None, block_id=None):
+        B, N, C = x.shape # 2 4096 1152
+        new_N = N
+        if HW is None:
+            H = W = int(N ** 0.5)
+        else:
+            H, W = HW
+        qkv = self.qkv(x).reshape(B, N, 3, C)
+
+        q, k, v = qkv.unbind(2)
+        dtype = q.dtype
+        q = self.q_norm(q)
+        k = self.k_norm(k)
+
+        # KV compression
+        if self.sr_ratio > 1:
+            k, new_N = self.downsample_2d(k, H, W, self.sr_ratio, sampling=self.sampling)
+            v, new_N = self.downsample_2d(v, H, W, self.sr_ratio, sampling=self.sampling)
+
+        q = q.reshape(B, N, self.num_heads, C // self.num_heads).to(dtype)
+        k = k.reshape(B, new_N, self.num_heads, C // self.num_heads).to(dtype)
+        v = v.reshape(B, new_N, self.num_heads, C // self.num_heads).to(dtype)
+
+        attn_bias = None
+        if mask is not None:
+            attn_bias = torch.zeros([B * self.num_heads, q.shape[1], k.shape[1]], dtype=q.dtype, device=q.device)
+            attn_bias.masked_fill_(mask.squeeze(1).repeat(self.num_heads, 1, 1) == 0, float('-inf'))
+        # Switch between torch / xformers attention
+        if model_management.xformers_enabled():
+            x = xformers.ops.memory_efficient_attention(
+                q, k, v,
+                p=self.attn_drop.p,
+                attn_bias=attn_bias
+            )
+        else:
+            q, k, v = map(lambda t: t.transpose(1, 2),(q, k, v),)
+            x = torch.nn.functional.scaled_dot_product_attention(
+                q, k, v,
+                attn_mask=attn_bias
+            ).transpose(1, 2).contiguous()
+        x = x.view(B, N, C)
+        x = self.proj(x)
+        x = self.proj_drop(x)
+        return x
 
 
 #################################################################################

PixArt/nodes.py

@@ -7,7 +7,6 @@ from comfy import utils
 from .conf import pixart_conf, pixart_res
 from .lora import load_pixart_lora
 from .loader import load_pixart
-from .sampler import sample_pixart
 
 class PixArtCheckpointLoader:
 	@classmethod
@@ -141,44 +140,6 @@ class PixArtControlNetCond:
 			cond[c][1]["cn_hint"] = latent["samples"] * 0.18215
 		return (cond,)
 
-class PixArtDPMSampler:
-	"""
-	The sampler from the reference code.
-	"""
-	@classmethod
-	def INPUT_TYPES(s):
-		return {
-			"required": {
-				"model": ("MODEL", ),
-				"seed": ("INT", {"default": 0, "min": 0, "max": 0xffffffffffffffff}),
-				"steps": ("INT", {"default": 20, "min": 1, "max": 10000}),
-				"cfg": ("FLOAT", {"default": 4.5, "min": 0.0, "max": 100.0, "step":0.5, "round": 0.01}),
-				"noise_schedule": (["linear","squaredcos_cap_v2"],{"default":"linear"}),
-				"noise_schedule_vp": (["linear","discrete"],{"default":"discrete"}),
-				"positive": ("CONDITIONING", ),
-				"negative": ("CONDITIONING", ),
-				"latent_image": ("LATENT", ),
-			}
-		}
-	RETURN_TYPES = ("LATENT",)
-	FUNCTION = "sample"
-	CATEGORY = "ExtraModels/PixArt"
-	TITLE = "PixArt DPM Sampler [Reference]"
-
-	def sample(self, model, seed, steps, cfg, noise_schedule, noise_schedule_vp, positive, negative, latent_image):
-		samples = sample_pixart(
-			model    = model,
-			seed     = seed,
-			steps    = steps,
-			cfg      = cfg,
-			positive = positive,
-			negative = negative,
-			latent_image = latent_image["samples"],
-			noise_schedule = noise_schedule,
-			noise_schedule_vp = noise_schedule_vp,
-		)
-		return ({"samples":samples},)
-
 class PixArtT5TextEncode:
 	"""
 	Reference code, mostly to verify compatibility.
@@ -236,7 +197,6 @@ NODE_CLASS_MAPPINGS = {
 	"PixArtCheckpointLoader" : PixArtCheckpointLoader,
 	"PixArtResolutionSelect" : PixArtResolutionSelect,
 	"PixArtLoraLoader" : PixArtLoraLoader,
-	"PixArtDPMSampler" : PixArtDPMSampler,
 	"PixArtT5TextEncode" : PixArtT5TextEncode,
 	"PixArtResolutionCond" : PixArtResolutionCond,
 	"PixArtControlNetCond" : PixArtControlNetCond,

PixArt/sampler.py

@@ -1,72 +0,0 @@
-import torch
-from .sampling import gaussian_diffusion as gd
-from .sampling.dpm_solver import model_wrapper, DPM_Solver, NoiseScheduleVP
-
-from comfy.sample import prepare_sampling, prepare_noise
-import comfy.utils
-import latent_preview
-
-def sample_pixart(model, seed, steps, cfg, noise_schedule, noise_schedule_vp, positive, negative, latent_image):
-	"""
-	Mostly just a wrapper around the reference code.
-	"""
-	# prepare model
-	noise = prepare_noise(latent_image, seed)
-	real_model, _, _, _, models = prepare_sampling(model, noise.shape, positive, negative, noise_mask=None)
-
-	# negative cond
-	cond = positive[0][0]
-	raw_uncond = negative[0][0]
-
-	# Sampler seems to want the same dim for cond and uncond
-	#  truncate uncond to the length of cond
-	#  if shorter, pad uncond with y_null
-	null_y = real_model.diffusion_model.y_embedder.y_embedding[None].repeat(latent_image.shape[0], 1, 1)
-	uncond = null_y[:, :cond.shape[1], :]
-	uncond[:, :raw_uncond.shape[1], :] = raw_uncond[:, :cond.shape[1], :]
-	if raw_uncond.shape[1] > cond.shape[1]:
-		print("PixArt: Warning. Your negative prompt is too long.")
-		uncond[:, -1, :] = raw_uncond[:, -1, :] # add back EOS token
-
-	# Move inputs
-	cond = cond.to(model.load_device).to(real_model.diffusion_model.dtype)
-	uncond = uncond.to(model.load_device).to(real_model.diffusion_model.dtype)
-	noise = noise.to(model.load_device).to(real_model.diffusion_model.dtype)
-
-	# preview
-	pbar = comfy.utils.ProgressBar(steps)
-	previewer = latent_preview.get_previewer(model.load_device, model.model.latent_format)
-
-	## Noise schedule.
-	betas = torch.tensor(gd.get_named_beta_schedule(noise_schedule, 1000))
-	noise_schedule = NoiseScheduleVP(schedule=noise_schedule_vp, betas=betas)
-
-	## Convert your discrete-time `model` to the continuous-time
-	## noise prediction model. Here is an example for a diffusion model
-	## `model` with the noise prediction type ("noise") .
-	model_fn = model_wrapper(
-		real_model.diffusion_model.forward,
-		noise_schedule,
-		model_type="noise", # 'noise', "x_start", "v", "score"
-		model_kwargs={},
-		guidance_type="classifier-free",
-		condition=cond,
-		unconditional_condition=uncond,
-		guidance_scale=cfg,
-	)
-	dpm_solver = DPM_Solver(
-		model_fn,
-		noise_schedule,
-		algorithm_type="dpmsolver++"
-	)
-	samples = dpm_solver.sample(
-		noise,
-		steps=steps,
-		order=2,
-		skip_type="time_uniform",
-		method="multistep",
-		pbar=pbar,
-		previewer=previewer,
-	)
-
-	return samples.detach().cpu().float() * (1 / model.model.latent_format.scale_factor)

PixArt/sampling/diffusion_utils.py

@@ -1,88 +0,0 @@
-# Modified from OpenAI's diffusion repos
-#     GLIDE: https://github.com/openai/glide-text2im/blob/main/glide_text2im/gaussian_diffusion.py
-#     ADM:   https://github.com/openai/guided-diffusion/blob/main/guided_diffusion
-#     IDDPM: https://github.com/openai/improved-diffusion/blob/main/improved_diffusion/gaussian_diffusion.py
-
-import numpy as np
-import torch as th
-
-
-def normal_kl(mean1, logvar1, mean2, logvar2):
-    """
-    Compute the KL divergence between two gaussians.
-    Shapes are automatically broadcasted, so batches can be compared to
-    scalars, among other use cases.
-    """
-    tensor = None
-    for obj in (mean1, logvar1, mean2, logvar2):
-        if isinstance(obj, th.Tensor):
-            tensor = obj
-            break
-    assert tensor is not None, "at least one argument must be a Tensor"
-
-    # Force variances to be Tensors. Broadcasting helps convert scalars to
-    # Tensors, but it does not work for th.exp().
-    logvar1, logvar2 = [
-        x if isinstance(x, th.Tensor) else th.tensor(x, device=tensor.device)
-        for x in (logvar1, logvar2)
-    ]
-
-    return 0.5 * (
-        -1.0
-        + logvar2
-        - logvar1
-        + th.exp(logvar1 - logvar2)
-        + ((mean1 - mean2) ** 2) * th.exp(-logvar2)
-    )
-
-
-def approx_standard_normal_cdf(x):
-    """
-    A fast approximation of the cumulative distribution function of the
-    standard normal.
-    """
-    return 0.5 * (1.0 + th.tanh(np.sqrt(2.0 / np.pi) * (x + 0.044715 * th.pow(x, 3))))
-
-
-def continuous_gaussian_log_likelihood(x, *, means, log_scales):
-    """
-    Compute the log-likelihood of a continuous Gaussian distribution.
-    :param x: the targets
-    :param means: the Gaussian mean Tensor.
-    :param log_scales: the Gaussian log stddev Tensor.
-    :return: a tensor like x of log probabilities (in nats).
-    """
-    centered_x = x - means
-    inv_stdv = th.exp(-log_scales)
-    normalized_x = centered_x * inv_stdv
-    log_probs = th.distributions.Normal(th.zeros_like(x), th.ones_like(x)).log_prob(normalized_x)
-    return log_probs
-
-
-def discretized_gaussian_log_likelihood(x, *, means, log_scales):
-    """
-    Compute the log-likelihood of a Gaussian distribution discretizing to a
-    given image.
-    :param x: the target images. It is assumed that this was uint8 values,
-              rescaled to the range [-1, 1].
-    :param means: the Gaussian mean Tensor.
-    :param log_scales: the Gaussian log stddev Tensor.
-    :return: a tensor like x of log probabilities (in nats).
-    """
-    assert x.shape == means.shape == log_scales.shape
-    centered_x = x - means
-    inv_stdv = th.exp(-log_scales)
-    plus_in = inv_stdv * (centered_x + 1.0 / 255.0)
-    cdf_plus = approx_standard_normal_cdf(plus_in)
-    min_in = inv_stdv * (centered_x - 1.0 / 255.0)
-    cdf_min = approx_standard_normal_cdf(min_in)
-    log_cdf_plus = th.log(cdf_plus.clamp(min=1e-12))
-    log_one_minus_cdf_min = th.log((1.0 - cdf_min).clamp(min=1e-12))
-    cdf_delta = cdf_plus - cdf_min
-    log_probs = th.where(
-        x < -0.999,
-        log_cdf_plus,
-        th.where(x > 0.999, log_one_minus_cdf_min, th.log(cdf_delta.clamp(min=1e-12))),
-    )
-    assert log_probs.shape == x.shape
-    return log_probs

PixArt/sampling/gaussian_diffusion.py

@@ -1,908 +0,0 @@
-# Modified from OpenAI's diffusion repos
-#     GLIDE: https://github.com/openai/glide-text2im/blob/main/glide_text2im/gaussian_diffusion.py
-#     ADM:   https://github.com/openai/guided-diffusion/blob/main/guided_diffusion
-#     IDDPM: https://github.com/openai/improved-diffusion/blob/main/improved_diffusion/gaussian_diffusion.py
-
-
-import enum
-import math
-
-import numpy as np
-import torch as th
-import torch.nn.functional as F
-
-from .diffusion_utils import discretized_gaussian_log_likelihood, normal_kl
-
-
-def mean_flat(tensor):
-    """
-    Take the mean over all non-batch dimensions.
-    """
-    return tensor.mean(dim=list(range(1, len(tensor.shape))))
-
-
-class ModelMeanType(enum.Enum):
-    """
-    Which type of output the model predicts.
-    """
-
-    PREVIOUS_X = enum.auto()  # the model predicts x_{t-1}
-    START_X = enum.auto()  # the model predicts x_0
-    EPSILON = enum.auto()  # the model predicts epsilon
-
-
-class ModelVarType(enum.Enum):
-    """
-    What is used as the model's output variance.
-    The LEARNED_RANGE option has been added to allow the model to predict
-    values between FIXED_SMALL and FIXED_LARGE, making its job easier.
-    """
-
-    LEARNED = enum.auto()
-    FIXED_SMALL = enum.auto()
-    FIXED_LARGE = enum.auto()
-    LEARNED_RANGE = enum.auto()
-
-
-class LossType(enum.Enum):
-    MSE = enum.auto()  # use raw MSE loss (and KL when learning variances)
-    RESCALED_MSE = (
-        enum.auto()
-    )  # use raw MSE loss (with RESCALED_KL when learning variances)
-    KL = enum.auto()  # use the variational lower-bound
-    RESCALED_KL = enum.auto()  # like KL, but rescale to estimate the full VLB
-
-    def is_vb(self):
-        return self == LossType.KL or self == LossType.RESCALED_KL
-
-
-def _warmup_beta(beta_start, beta_end, num_diffusion_timesteps, warmup_frac):
-    betas = beta_end * np.ones(num_diffusion_timesteps, dtype=np.float64)
-    warmup_time = int(num_diffusion_timesteps * warmup_frac)
-    betas[:warmup_time] = np.linspace(beta_start, beta_end, warmup_time, dtype=np.float64)
-    return betas
-
-
-def get_beta_schedule(beta_schedule, *, beta_start, beta_end, num_diffusion_timesteps):
-    """
-    This is the deprecated API for creating beta schedules.
-    See get_named_beta_schedule() for the new library of schedules.
-    """
-    if beta_schedule == "quad":
-        betas = (
-            np.linspace(
-                beta_start ** 0.5,
-                beta_end ** 0.5,
-                num_diffusion_timesteps,
-                dtype=np.float64,
-            )
-            ** 2
-        )
-    elif beta_schedule == "linear":
-        betas = np.linspace(beta_start, beta_end, num_diffusion_timesteps, dtype=np.float64)
-    elif beta_schedule == "warmup10":
-        betas = _warmup_beta(beta_start, beta_end, num_diffusion_timesteps, 0.1)
-    elif beta_schedule == "warmup50":
-        betas = _warmup_beta(beta_start, beta_end, num_diffusion_timesteps, 0.5)
-    elif beta_schedule == "const":
-        betas = beta_end * np.ones(num_diffusion_timesteps, dtype=np.float64)
-    elif beta_schedule == "jsd":  # 1/T, 1/(T-1), 1/(T-2), ..., 1
-        betas = 1.0 / np.linspace(
-            num_diffusion_timesteps, 1, num_diffusion_timesteps, dtype=np.float64
-        )
-    else:
-        raise NotImplementedError(beta_schedule)
-    assert betas.shape == (num_diffusion_timesteps,)
-    return betas
-
-
-def get_named_beta_schedule(schedule_name, num_diffusion_timesteps):
-    """
-    Get a pre-defined beta schedule for the given name.
-    The beta schedule library consists of beta schedules which remain similar
-    in the limit of num_diffusion_timesteps.
-    Beta schedules may be added, but should not be removed or changed once
-    they are committed to maintain backwards compatibility.
-    """
-    if schedule_name == "linear":
-        # Linear schedule from Ho et al, extended to work for any number of
-        # diffusion steps.
-        scale = 1000 / num_diffusion_timesteps
-        return get_beta_schedule(
-            "linear",
-            beta_start=scale * 0.0001,
-            beta_end=scale * 0.02,
-            num_diffusion_timesteps=num_diffusion_timesteps,
-        )
-    elif schedule_name == "squaredcos_cap_v2":
-        return betas_for_alpha_bar(
-            num_diffusion_timesteps,
-            lambda t: math.cos((t + 0.008) / 1.008 * math.pi / 2) ** 2,
-        )
-    else:
-        raise NotImplementedError(f"unknown beta schedule: {schedule_name}")
-
-
-def betas_for_alpha_bar(num_diffusion_timesteps, alpha_bar, max_beta=0.999):
-    """
-    Create a beta schedule that discretizes the given alpha_t_bar function,
-    which defines the cumulative product of (1-beta) over time from t = [0,1].
-    :param num_diffusion_timesteps: the number of betas to produce.
-    :param alpha_bar: a lambda that takes an argument t from 0 to 1 and
-                      produces the cumulative product of (1-beta) up to that
-                      part of the diffusion process.
-    :param max_beta: the maximum beta to use; use values lower than 1 to
-                     prevent singularities.
-    """
-    betas = []
-    for i in range(num_diffusion_timesteps):
-        t1 = i / num_diffusion_timesteps
-        t2 = (i + 1) / num_diffusion_timesteps
-        betas.append(min(1 - alpha_bar(t2) / alpha_bar(t1), max_beta))
-    return np.array(betas)
-
-
-class GaussianDiffusion:
-    """
-    Utilities for training and sampling diffusion models.
-    Original ported from this codebase:
-    https://github.com/hojonathanho/diffusion/blob/1e0dceb3b3495bbe19116a5e1b3596cd0706c543/diffusion_tf/diffusion_utils_2.py#L42
-    :param betas: a 1-D numpy array of betas for each diffusion timestep,
-                  starting at T and going to 1.
-    """
-
-    def __init__(
-        self,
-        *,
-        betas,
-        model_mean_type,
-        model_var_type,
-        loss_type,
-        snr=False
-    ):
-
-        self.model_mean_type = model_mean_type
-        self.model_var_type = model_var_type
-        self.loss_type = loss_type
-        self.snr = snr
-
-        # Use float64 for accuracy.
-        betas = np.array(betas, dtype=np.float64)
-        self.betas = betas
-        assert len(betas.shape) == 1, "betas must be 1-D"
-        assert (betas > 0).all() and (betas <= 1).all()
-
-        self.num_timesteps = int(betas.shape[0])
-
-        alphas = 1.0 - betas
-        self.alphas_cumprod = np.cumprod(alphas, axis=0)
-        self.alphas_cumprod_prev = np.append(1.0, self.alphas_cumprod[:-1])
-        self.alphas_cumprod_next = np.append(self.alphas_cumprod[1:], 0.0)
-        assert self.alphas_cumprod_prev.shape == (self.num_timesteps,)
-
-        # calculations for diffusion q(x_t | x_{t-1}) and others
-        self.sqrt_alphas_cumprod = np.sqrt(self.alphas_cumprod)
-        self.sqrt_one_minus_alphas_cumprod = np.sqrt(1.0 - self.alphas_cumprod)
-        self.log_one_minus_alphas_cumprod = np.log(1.0 - self.alphas_cumprod)
-        self.sqrt_recip_alphas_cumprod = np.sqrt(1.0 / self.alphas_cumprod)
-        self.sqrt_recipm1_alphas_cumprod = np.sqrt(1.0 / self.alphas_cumprod - 1)
-
-        # calculations for posterior q(x_{t-1} | x_t, x_0)
-        self.posterior_variance = (
-            betas * (1.0 - self.alphas_cumprod_prev) / (1.0 - self.alphas_cumprod)
-        )
-        # below: log calculation clipped because the posterior variance is 0 at the beginning of the diffusion chain
-        self.posterior_log_variance_clipped = np.log(
-            np.append(self.posterior_variance[1], self.posterior_variance[1:])
-        ) if len(self.posterior_variance) > 1 else np.array([])
-
-        self.posterior_mean_coef1 = (
-            betas * np.sqrt(self.alphas_cumprod_prev) / (1.0 - self.alphas_cumprod)
-        )
-        self.posterior_mean_coef2 = (
-            (1.0 - self.alphas_cumprod_prev) * np.sqrt(alphas) / (1.0 - self.alphas_cumprod)
-        )
-
-    def q_mean_variance(self, x_start, t):
-        """
-        Get the distribution q(x_t | x_0).
-        :param x_start: the [N x C x ...] tensor of noiseless inputs.
-        :param t: the number of diffusion steps (minus 1). Here, 0 means one step.
-        :return: A tuple (mean, variance, log_variance), all of x_start's shape.
-        """
-        mean = _extract_into_tensor(self.sqrt_alphas_cumprod, t, x_start.shape) * x_start
-        variance = _extract_into_tensor(1.0 - self.alphas_cumprod, t, x_start.shape)
-        log_variance = _extract_into_tensor(self.log_one_minus_alphas_cumprod, t, x_start.shape)
-        return mean, variance, log_variance
-
-    def q_sample(self, x_start, t, noise=None):
-        """
-        Diffuse the data for a given number of diffusion steps.
-        In other words, sample from q(x_t | x_0).
-        :param x_start: the initial data batch.
-        :param t: the number of diffusion steps (minus 1). Here, 0 means one step.
-        :param noise: if specified, the split-out normal noise.
-        :return: A noisy version of x_start.
-        """
-        if noise is None:
-            noise = th.randn_like(x_start)
-        assert noise.shape == x_start.shape
-        return (
-            _extract_into_tensor(self.sqrt_alphas_cumprod, t, x_start.shape) * x_start
-            + _extract_into_tensor(self.sqrt_one_minus_alphas_cumprod, t, x_start.shape) * noise
-        )
-
-    def q_posterior_mean_variance(self, x_start, x_t, t):
-        """
-        Compute the mean and variance of the diffusion posterior:
-            q(x_{t-1} | x_t, x_0)
-        """
-        assert x_start.shape == x_t.shape
-        posterior_mean = (
-            _extract_into_tensor(self.posterior_mean_coef1, t, x_t.shape) * x_start
-            + _extract_into_tensor(self.posterior_mean_coef2, t, x_t.shape) * x_t
-        )
-        posterior_variance = _extract_into_tensor(self.posterior_variance, t, x_t.shape)
-        posterior_log_variance_clipped = _extract_into_tensor(
-            self.posterior_log_variance_clipped, t, x_t.shape
-        )
-        assert (
-            posterior_mean.shape[0]
-            == posterior_variance.shape[0]
-            == posterior_log_variance_clipped.shape[0]
-            == x_start.shape[0]
-        )
-        return posterior_mean, posterior_variance, posterior_log_variance_clipped
-
-    def p_mean_variance(self, model, x, t, clip_denoised=True, denoised_fn=None, model_kwargs=None):
-        """
-        Apply the model to get p(x_{t-1} | x_t), as well as a prediction of
-        the initial x, x_0.
-        :param model: the model, which takes a signal and a batch of timesteps
-                      as input.
-        :param x: the [N x C x ...] tensor at time t.
-        :param t: a 1-D Tensor of timesteps.
-        :param clip_denoised: if True, clip the denoised signal into [-1, 1].
-        :param denoised_fn: if not None, a function which applies to the
-            x_start prediction before it is used to sample. Applies before
-            clip_denoised.
-        :param model_kwargs: if not None, a dict of extra keyword arguments to
-            pass to the model. This can be used for conditioning.
-        :return: a dict with the following keys:
-                 - 'mean': the model mean output.
-                 - 'variance': the model variance output.
-                 - 'log_variance': the log of 'variance'.
-                 - 'pred_xstart': the prediction for x_0.
-        """
-        if model_kwargs is None:
-            model_kwargs = {}
-
-        B, C = x.shape[:2]
-        assert t.shape == (B,)
-        model_output = model(x, t, **model_kwargs)
-        if isinstance(model_output, tuple):
-            model_output, extra = model_output
-        else:
-            extra = None
-
-        if self.model_var_type in [ModelVarType.LEARNED, ModelVarType.LEARNED_RANGE]:
-            assert model_output.shape == (B, C * 2, *x.shape[2:])
-            model_output, model_var_values = th.split(model_output, C, dim=1)
-            min_log = _extract_into_tensor(self.posterior_log_variance_clipped, t, x.shape)
-            max_log = _extract_into_tensor(np.log(self.betas), t, x.shape)
-            # The model_var_values is [-1, 1] for [min_var, max_var].
-            frac = (model_var_values + 1) / 2
-            model_log_variance = frac * max_log + (1 - frac) * min_log
-            model_variance = th.exp(model_log_variance)
-        elif self.model_var_type in [ModelVarType.FIXED_LARGE, ModelVarType.FIXED_SMALL]:
-            model_variance, model_log_variance = {
-                # for fixedlarge, we set the initial (log-)variance like so
-                # to get a better decoder log likelihood.
-                ModelVarType.FIXED_LARGE: (
-                    np.append(self.posterior_variance[1], self.betas[1:]),
-                    np.log(np.append(self.posterior_variance[1], self.betas[1:])),
-                ),
-                ModelVarType.FIXED_SMALL: (
-                    self.posterior_variance,
-                    self.posterior_log_variance_clipped,
-                ),
-            }[self.model_var_type]
-            model_variance = _extract_into_tensor(model_variance, t, x.shape)
-            model_log_variance = _extract_into_tensor(model_log_variance, t, x.shape)
-        else:
-            model_variance = th.zeros_like(model_output)
-            model_log_variance = th.zeros_like(model_output)
-
-        def process_xstart(x):
-            if denoised_fn is not None:
-                x = denoised_fn(x)
-            if clip_denoised:
-                return x.clamp(-1, 1)
-            return x
-
-        if self.model_mean_type == ModelMeanType.START_X:
-            pred_xstart = process_xstart(model_output)
-        else:
-            pred_xstart = process_xstart(
-                self._predict_xstart_from_eps(x_t=x, t=t, eps=model_output)
-            )
-        model_mean, _, _ = self.q_posterior_mean_variance(x_start=pred_xstart, x_t=x, t=t)
-
-        assert model_mean.shape == model_log_variance.shape == pred_xstart.shape == x.shape
-        return {
-            "mean": model_mean,
-            "variance": model_variance,
-            "log_variance": model_log_variance,
-            "pred_xstart": pred_xstart,
-            "extra": extra,
-        }
-
-    def _predict_xstart_from_eps(self, x_t, t, eps):
-        assert x_t.shape == eps.shape
-        return (
-            _extract_into_tensor(self.sqrt_recip_alphas_cumprod, t, x_t.shape) * x_t
-            - _extract_into_tensor(self.sqrt_recipm1_alphas_cumprod, t, x_t.shape) * eps
-        )
-
-    def _predict_eps_from_xstart(self, x_t, t, pred_xstart):
-        return (
-            _extract_into_tensor(self.sqrt_recip_alphas_cumprod, t, x_t.shape) * x_t - pred_xstart
-        ) / _extract_into_tensor(self.sqrt_recipm1_alphas_cumprod, t, x_t.shape)
-
-    def condition_mean(self, cond_fn, p_mean_var, x, t, model_kwargs=None):
-        """
-        Compute the mean for the previous step, given a function cond_fn that
-        computes the gradient of a conditional log probability with respect to
-        x. In particular, cond_fn computes grad(log(p(y|x))), and we want to
-        condition on y.
-        This uses the conditioning strategy from Sohl-Dickstein et al. (2015).
-        """
-        gradient = cond_fn(x, t, **model_kwargs)
-        new_mean = p_mean_var["mean"].float() + p_mean_var["variance"] * gradient.float()
-        return new_mean
-
-    def condition_score(self, cond_fn, p_mean_var, x, t, model_kwargs=None):
-        """
-        Compute what the p_mean_variance output would have been, should the
-        model's score function be conditioned by cond_fn.
-        See condition_mean() for details on cond_fn.
-        Unlike condition_mean(), this instead uses the conditioning strategy
-        from Song et al (2020).
-        """
-        alpha_bar = _extract_into_tensor(self.alphas_cumprod, t, x.shape)
-
-        eps = self._predict_eps_from_xstart(x, t, p_mean_var["pred_xstart"])
-        eps = eps - (1 - alpha_bar).sqrt() * cond_fn(x, t, **model_kwargs)
-
-        out = p_mean_var.copy()
-        out["pred_xstart"] = self._predict_xstart_from_eps(x, t, eps)
-        out["mean"], _, _ = self.q_posterior_mean_variance(x_start=out["pred_xstart"], x_t=x, t=t)
-        return out
-
-    def p_sample(
-        self,
-        model,
-        x,
-        t,
-        clip_denoised=True,
-        denoised_fn=None,
-        cond_fn=None,
-        model_kwargs=None,
-    ):
-        """
-        Sample x_{t-1} from the model at the given timestep.
-        :param model: the model to sample from.
-        :param x: the current tensor at x_{t-1}.
-        :param t: the value of t, starting at 0 for the first diffusion step.
-        :param clip_denoised: if True, clip the x_start prediction to [-1, 1].
-        :param denoised_fn: if not None, a function which applies to the
-            x_start prediction before it is used to sample.
-        :param cond_fn: if not None, this is a gradient function that acts
-                        similarly to the model.
-        :param model_kwargs: if not None, a dict of extra keyword arguments to
-            pass to the model. This can be used for conditioning.
-        :return: a dict containing the following keys:
-                 - 'sample': a random sample from the model.
-                 - 'pred_xstart': a prediction of x_0.
-        """
-        out = self.p_mean_variance(
-            model,
-            x,
-            t,
-            clip_denoised=clip_denoised,
-            denoised_fn=denoised_fn,
-            model_kwargs=model_kwargs,
-        )
-        noise = th.randn_like(x)
-        nonzero_mask = (
-            (t != 0).float().view(-1, *([1] * (len(x.shape) - 1)))
-        )  # no noise when t == 0
-        if cond_fn is not None:
-            out["mean"] = self.condition_mean(cond_fn, out, x, t, model_kwargs=model_kwargs)
-        sample = out["mean"] + nonzero_mask * th.exp(0.5 * out["log_variance"]) * noise
-        return {"sample": sample, "pred_xstart": out["pred_xstart"]}
-
-    def p_sample_loop(
-        self,
-        model,
-        shape,
-        noise=None,
-        clip_denoised=True,
-        denoised_fn=None,
-        cond_fn=None,
-        model_kwargs=None,
-        device=None,
-        progress=False,
-    ):
-        """
-        Generate samples from the model.
-        :param model: the model module.
-        :param shape: the shape of the samples, (N, C, H, W).
-        :param noise: if specified, the noise from the encoder to sample.
-                      Should be of the same shape as `shape`.
-        :param clip_denoised: if True, clip x_start predictions to [-1, 1].
-        :param denoised_fn: if not None, a function which applies to the
-            x_start prediction before it is used to sample.
-        :param cond_fn: if not None, this is a gradient function that acts
-                        similarly to the model.
-        :param model_kwargs: if not None, a dict of extra keyword arguments to
-            pass to the model. This can be used for conditioning.
-        :param device: if specified, the device to create the samples on.
-                       If not specified, use a model parameter's device.
-        :param progress: if True, show a tqdm progress bar.
-        :return: a non-differentiable batch of samples.
-        """
-        final = None
-        for sample in self.p_sample_loop_progressive(
-            model,
-            shape,
-            noise=noise,
-            clip_denoised=clip_denoised,
-            denoised_fn=denoised_fn,
-            cond_fn=cond_fn,
-            model_kwargs=model_kwargs,
-            device=device,
-            progress=progress,
-        ):
-            final = sample
-        return final["sample"]
-
-    def p_sample_loop_progressive(
-        self,
-        model,
-        shape,
-        noise=None,
-        clip_denoised=True,
-        denoised_fn=None,
-        cond_fn=None,
-        model_kwargs=None,
-        device=None,
-        progress=False,
-    ):
-        """
-        Generate samples from the model and yield intermediate samples from
-        each timestep of diffusion.
-        Arguments are the same as p_sample_loop().
-        Returns a generator over dicts, where each dict is the return value of
-        p_sample().
-        """
-        if device is None:
-            device = next(model.parameters()).device
-        assert isinstance(shape, (tuple, list))
-        if noise is not None:
-            img = noise
-        else:
-            img = th.randn(*shape, device=device)
-        indices = list(range(self.num_timesteps))[::-1]
-
-        if progress:
-            # Lazy import so that we don't depend on tqdm.
-            from tqdm.auto import tqdm
-
-            indices = tqdm(indices)
-
-        for i in indices:
-            t = th.tensor([i] * shape[0], device=device)
-            with th.no_grad():
-                out = self.p_sample(
-                    model,
-                    img,
-                    t,
-                    clip_denoised=clip_denoised,
-                    denoised_fn=denoised_fn,
-                    cond_fn=cond_fn,
-                    model_kwargs=model_kwargs,
-                )
-                yield out
-                img = out["sample"]
-
-    def ddim_sample(
-        self,
-        model,
-        x,
-        t,
-        clip_denoised=True,
-        denoised_fn=None,
-        cond_fn=None,
-        model_kwargs=None,
-        eta=0.0,
-    ):
-        """
-        Sample x_{t-1} from the model using DDIM.
-        Same usage as p_sample().
-        """
-        out = self.p_mean_variance(
-            model,
-            x,
-            t,
-            clip_denoised=clip_denoised,
-            denoised_fn=denoised_fn,
-            model_kwargs=model_kwargs,
-        )
-        if cond_fn is not None:
-            out = self.condition_score(cond_fn, out, x, t, model_kwargs=model_kwargs)
-
-        # Usually our model outputs epsilon, but we re-derive it
-        # in case we used x_start or x_prev prediction.
-        eps = self._predict_eps_from_xstart(x, t, out["pred_xstart"])
-
-        alpha_bar = _extract_into_tensor(self.alphas_cumprod, t, x.shape)
-        alpha_bar_prev = _extract_into_tensor(self.alphas_cumprod_prev, t, x.shape)
-        sigma = (
-            eta
-            * th.sqrt((1 - alpha_bar_prev) / (1 - alpha_bar))
-            * th.sqrt(1 - alpha_bar / alpha_bar_prev)
-        )
-        # Equation 12.
-        noise = th.randn_like(x)
-        mean_pred = (
-            out["pred_xstart"] * th.sqrt(alpha_bar_prev)
-            + th.sqrt(1 - alpha_bar_prev - sigma ** 2) * eps
-        )
-        nonzero_mask = (
-            (t != 0).float().view(-1, *([1] * (len(x.shape) - 1)))
-        )  # no noise when t == 0
-        sample = mean_pred + nonzero_mask * sigma * noise
-        return {"sample": sample, "pred_xstart": out["pred_xstart"]}
-
-    def ddim_reverse_sample(
-        self,
-        model,
-        x,
-        t,
-        clip_denoised=True,
-        denoised_fn=None,
-        cond_fn=None,
-        model_kwargs=None,
-        eta=0.0,
-    ):
-        """
-        Sample x_{t+1} from the model using DDIM reverse ODE.
-        """
-        assert eta == 0.0, "Reverse ODE only for deterministic path"
-        out = self.p_mean_variance(
-            model,
-            x,
-            t,
-            clip_denoised=clip_denoised,
-            denoised_fn=denoised_fn,
-            model_kwargs=model_kwargs,
-        )
-        if cond_fn is not None:
-            out = self.condition_score(cond_fn, out, x, t, model_kwargs=model_kwargs)
-        # Usually our model outputs epsilon, but we re-derive it
-        # in case we used x_start or x_prev prediction.
-        eps = (
-            _extract_into_tensor(self.sqrt_recip_alphas_cumprod, t, x.shape) * x
-            - out["pred_xstart"]
-        ) / _extract_into_tensor(self.sqrt_recipm1_alphas_cumprod, t, x.shape)
-        alpha_bar_next = _extract_into_tensor(self.alphas_cumprod_next, t, x.shape)
-
-        # Equation 12. reversed
-        mean_pred = out["pred_xstart"] * th.sqrt(alpha_bar_next) + th.sqrt(1 - alpha_bar_next) * eps
-
-        return {"sample": mean_pred, "pred_xstart": out["pred_xstart"]}
-
-    def ddim_sample_loop(
-        self,
-        model,
-        shape,
-        noise=None,
-        clip_denoised=True,
-        denoised_fn=None,
-        cond_fn=None,
-        model_kwargs=None,
-        device=None,
-        progress=False,
-        eta=0.0,
-    ):
-        """
-        Generate samples from the model using DDIM.
-        Same usage as p_sample_loop().
-        """
-        final = None
-        for sample in self.ddim_sample_loop_progressive(
-            model,
-            shape,
-            noise=noise,
-            clip_denoised=clip_denoised,
-            denoised_fn=denoised_fn,
-            cond_fn=cond_fn,
-            model_kwargs=model_kwargs,
-            device=device,
-            progress=progress,
-            eta=eta,
-        ):
-            final = sample
-        return final["sample"]
-
-    def ddim_sample_loop_progressive(
-        self,
-        model,
-        shape,
-        noise=None,
-        clip_denoised=True,
-        denoised_fn=None,
-        cond_fn=None,
-        model_kwargs=None,
-        device=None,
-        progress=False,
-        eta=0.0,
-    ):
-        """
-        Use DDIM to sample from the model and yield intermediate samples from
-        each timestep of DDIM.
-        Same usage as p_sample_loop_progressive().
-        """
-        if device is None:
-            device = next(model.parameters()).device
-        assert isinstance(shape, (tuple, list))
-        if noise is not None:
-            img = noise
-        else:
-            img = th.randn(*shape, device=device)
-        indices = list(range(self.num_timesteps))[::-1]
-
-        if progress:
-            # Lazy import so that we don't depend on tqdm.
-            from tqdm.auto import tqdm
-
-            indices = tqdm(indices)
-
-        for i in indices:
-            t = th.tensor([i] * shape[0], device=device)
-            with th.no_grad():
-                out = self.ddim_sample(
-                    model,
-                    img,
-                    t,
-                    clip_denoised=clip_denoised,
-                    denoised_fn=denoised_fn,
-                    cond_fn=cond_fn,
-                    model_kwargs=model_kwargs,
-                    eta=eta,
-                )
-                yield out
-                img = out["sample"]
-
-    def _vb_terms_bpd(
-            self, model, x_start, x_t, t, clip_denoised=True, model_kwargs=None
-    ):
-        """
-        Get a term for the variational lower-bound.
-        The resulting units are bits (rather than nats, as one might expect).
-        This allows for comparison to other papers.
-        :return: a dict with the following keys:
-                 - 'output': a shape [N] tensor of NLLs or KLs.
-                 - 'pred_xstart': the x_0 predictions.
-        """
-        true_mean, _, true_log_variance_clipped = self.q_posterior_mean_variance(
-            x_start=x_start, x_t=x_t, t=t
-        )
-        out = self.p_mean_variance(
-            model, x_t, t, clip_denoised=clip_denoised, model_kwargs=model_kwargs
-        )
-        kl = normal_kl(
-            true_mean, true_log_variance_clipped, out["mean"], out["log_variance"]
-        )
-        kl = mean_flat(kl) / np.log(2.0)
-
-        decoder_nll = -discretized_gaussian_log_likelihood(
-            x_start, means=out["mean"], log_scales=0.5 * out["log_variance"]
-        )
-        assert decoder_nll.shape == x_start.shape
-        decoder_nll = mean_flat(decoder_nll) / np.log(2.0)
-
-        # At the first timestep return the decoder NLL,
-        # otherwise return KL(q(x_{t-1}|x_t,x_0) || p(x_{t-1}|x_t))
-        output = th.where((t == 0), decoder_nll, kl)
-        return {"output": output, "pred_xstart": out["pred_xstart"]}
-
-    def training_losses(self, model, x_start, t, model_kwargs=None, noise=None):
-        """
-        Compute training losses for a single timestep.
-        :param model: the model to evaluate loss on.
-        :param x_start: the [N x C x ...] tensor of inputs.
-        :param t: a batch of timestep indices.
-        :param model_kwargs: if not None, a dict of extra keyword arguments to
-            pass to the model. This can be used for conditioning.
-        :param noise: if specified, the specific Gaussian noise to try to remove.
-        :return: a dict with the key "loss" containing a tensor of shape [N].
-                 Some mean or variance settings may also have other keys.
-        """
-        if model_kwargs is None:
-            model_kwargs = {}
-        if noise is None:
-            noise = th.randn_like(x_start)
-        x_t = self.q_sample(x_start, t, noise=noise)
-
-        terms = {}
-
-        if self.loss_type == LossType.KL or self.loss_type == LossType.RESCALED_KL:
-            terms["loss"] = self._vb_terms_bpd(
-                model=model,
-                x_start=x_start,
-                x_t=x_t,
-                t=t,
-                clip_denoised=False,
-                model_kwargs=model_kwargs,
-            )["output"]
-            if self.loss_type == LossType.RESCALED_KL:
-                terms["loss"] *= self.num_timesteps
-        elif self.loss_type == LossType.MSE or self.loss_type == LossType.RESCALED_MSE:
-            model_output = model(x_t, t, **model_kwargs)
-            if isinstance(model_output, dict) and model_output.get('x', None) is not None:
-                output = model_output['x']
-            else:
-                output = model_output
-
-            if self.model_var_type in [
-                ModelVarType.LEARNED,
-                ModelVarType.LEARNED_RANGE,
-            ]:
-                B, C = x_t.shape[:2]
-                assert output.shape == (B, C * 2, *x_t.shape[2:])
-                output, model_var_values = th.split(output, C, dim=1)
-                # Learn the variance using the variational bound, but don't let it affect our mean prediction.
-                frozen_out = th.cat([output.detach(), model_var_values], dim=1)
-                terms["vb"] = self._vb_terms_bpd(
-                    model=lambda *args, r=frozen_out: r,
-                    x_start=x_start,
-                    x_t=x_t,
-                    t=t,
-                    clip_denoised=False,
-                )["output"]
-                if self.loss_type == LossType.RESCALED_MSE:
-                    # Divide by 1000 for equivalence with initial implementation.
-                    # Without a factor of 1/1000, the VB term hurts the MSE term.
-                    terms["vb"] *= self.num_timesteps / 1000.0
-
-            target = {
-                ModelMeanType.PREVIOUS_X: self.q_posterior_mean_variance(
-                    x_start=x_start, x_t=x_t, t=t
-                )[0],
-                ModelMeanType.START_X: x_start,
-                ModelMeanType.EPSILON: noise,
-            }[self.model_mean_type]
-            assert output.shape == target.shape == x_start.shape
-            if self.snr:
-                if self.model_mean_type == ModelMeanType.START_X:
-                    pred_noise = self._predict_eps_from_xstart(x_t=x_t, t=t, pred_xstart=output)
-                    pred_startx = output
-                elif self.model_mean_type == ModelMeanType.EPSILON:
-                    pred_noise = output
-                    pred_startx = self._predict_xstart_from_eps(x_t=x_t, t=t, eps=output)
-                # terms["mse_eps"] = mean_flat((noise - pred_noise) ** 2)
-                # terms["mse_x0"] = mean_flat((x_start - pred_startx) ** 2)
-
-                t = t[:, None, None, None].expand(pred_startx.shape)  # [128, 4, 32, 32]
-                # best
-                target = th.where(t > 249, noise, x_start)
-                output = th.where(t > 249, pred_noise, pred_startx)
-            loss = (target - output) ** 2
-            if model_kwargs.get('mask_ratio', False) and model_kwargs['mask_ratio'] > 0:
-                assert 'mask' in model_output
-                loss = F.avg_pool2d(loss.mean(dim=1), model.model.module.patch_size).flatten(1)
-                mask = model_output['mask']
-                unmask = 1 - mask
-                terms['mse'] = mean_flat(loss * unmask) * unmask.shape[1]/unmask.sum(1)
-                if model_kwargs['mask_loss_coef'] > 0:
-                    terms['mae'] = model_kwargs['mask_loss_coef'] * mean_flat(loss * mask) * mask.shape[1]/mask.sum(1)
-            else:
-                terms["mse"] = mean_flat(loss)
-            if "vb" in terms:
-                terms["loss"] = terms["mse"] + terms["vb"]
-            else:
-                terms["loss"] = terms["mse"]
-            if "mae" in terms:
-                terms["loss"] = terms["loss"] + terms["mae"]
-        else:
-            raise NotImplementedError(self.loss_type)
-
-        return terms
-
-    def _prior_bpd(self, x_start):
-        """
-        Get the prior KL term for the variational lower-bound, measured in
-        bits-per-dim.
-        This term can't be optimized, as it only depends on the encoder.
-        :param x_start: the [N x C x ...] tensor of inputs.
-        :return: a batch of [N] KL values (in bits), one per batch element.
-        """
-        batch_size = x_start.shape[0]
-        t = th.tensor([self.num_timesteps - 1] * batch_size, device=x_start.device)
-        qt_mean, _, qt_log_variance = self.q_mean_variance(x_start, t)
-        kl_prior = normal_kl(
-            mean1=qt_mean, logvar1=qt_log_variance, mean2=0.0, logvar2=0.0
-        )
-        return mean_flat(kl_prior) / np.log(2.0)
-
-    def calc_bpd_loop(self, model, x_start, clip_denoised=True, model_kwargs=None):
-        """
-        Compute the entire variational lower-bound, measured in bits-per-dim,
-        as well as other related quantities.
-        :param model: the model to evaluate loss on.
-        :param x_start: the [N x C x ...] tensor of inputs.
-        :param clip_denoised: if True, clip denoised samples.
-        :param model_kwargs: if not None, a dict of extra keyword arguments to
-            pass to the model. This can be used for conditioning.
-        :return: a dict containing the following keys:
-                 - total_bpd: the total variational lower-bound, per batch element.
-                 - prior_bpd: the prior term in the lower-bound.
-                 - vb: an [N x T] tensor of terms in the lower-bound.
-                 - xstart_mse: an [N x T] tensor of x_0 MSEs for each timestep.
-                 - mse: an [N x T] tensor of epsilon MSEs for each timestep.
-        """
-        device = x_start.device
-        batch_size = x_start.shape[0]
-
-        vb = []
-        xstart_mse = []
-        mse = []
-        for t in list(range(self.num_timesteps))[::-1]:
-            t_batch = th.tensor([t] * batch_size, device=device)
-            noise = th.randn_like(x_start)
-            x_t = self.q_sample(x_start=x_start, t=t_batch, noise=noise)
-            # Calculate VLB term at the current timestep
-            with th.no_grad():
-                out = self._vb_terms_bpd(
-                    model,
-                    x_start=x_start,
-                    x_t=x_t,
-                    t=t_batch,
-                    clip_denoised=clip_denoised,
-                    model_kwargs=model_kwargs,
-                )
-            vb.append(out["output"])
-            xstart_mse.append(mean_flat((out["pred_xstart"] - x_start) ** 2))
-            eps = self._predict_eps_from_xstart(x_t, t_batch, out["pred_xstart"])
-            mse.append(mean_flat((eps - noise) ** 2))
-
-        vb = th.stack(vb, dim=1)
-        xstart_mse = th.stack(xstart_mse, dim=1)
-        mse = th.stack(mse, dim=1)
-
-        prior_bpd = self._prior_bpd(x_start)
-        total_bpd = vb.sum(dim=1) + prior_bpd
-        return {
-            "total_bpd": total_bpd,
-            "prior_bpd": prior_bpd,
-            "vb": vb,
-            "xstart_mse": xstart_mse,
-            "mse": mse,
-        }
-
-
-def _extract_into_tensor(arr, timesteps, broadcast_shape):
-    """
-    Extract values from a 1-D numpy array for a batch of indices.
-    :param arr: the 1-D numpy array.
-    :param timesteps: a tensor of indices into the array to extract.
-    :param broadcast_shape: a larger shape of K dimensions with the batch
-                            dimension equal to the length of timesteps.
-    :return: a tensor of shape [batch_size, 1, ...] where the shape has K dims.
-    """
-    res = th.from_numpy(arr).to(device=timesteps.device)[timesteps].float()
-    while len(res.shape) < len(broadcast_shape):
-        res = res[..., None]
-    return res + th.zeros(broadcast_shape, device=timesteps.device)

README.md

@@ -70,6 +70,15 @@ Limitations:
 
 ![PixArtT12](https://github.com/city96/ComfyUI_ExtraModels/assets/125218114/eb1a02f9-6114-47eb-a066-261c39c55615)
 
+### PixArt Sigma
+
+Currently only the early 256 and 512 checkpoints are released, out of which only the 512 is supported in this custom node pack.
+
+You can find the [512 checkpoint here](https://huggingface.co/PixArt-alpha/PixArt-Sigma/blob/main/PixArt-Sigma-XL-2-512-MS.pth). Place it in your models folder and select the appropriate type in the model loader / resolution selection node.
+
+> [!IMPORTANT]
+> Make sure to select an SDXL VAE for PixArt Sigma!
+
 ### PixArt LCM
 
 The LCM model also works if you're on the latest version. To use it: