soon is now

sgm/modules/diffusionmodules/__init__.py

@@ -0,0 +1,7 @@
+from .denoiser import Denoiser
+from .discretizer import Discretization
+from .loss import StandardDiffusionLoss
+from .model import Model, Encoder, Decoder
+from .openaimodel import UNetModel
+from .sampling import BaseDiffusionSampler
+from .wrappers import OpenAIWrapper

sgm/modules/diffusionmodules/denoiser.py

@@ -0,0 +1,63 @@
+import torch.nn as nn
+
+from ...util import append_dims, instantiate_from_config
+
+
+class Denoiser(nn.Module):
+    def __init__(self, weighting_config, scaling_config):
+        super().__init__()
+
+        self.weighting = instantiate_from_config(weighting_config)
+        self.scaling = instantiate_from_config(scaling_config)
+
+    def possibly_quantize_sigma(self, sigma):
+        return sigma
+
+    def possibly_quantize_c_noise(self, c_noise):
+        return c_noise
+
+    def w(self, sigma):
+        return self.weighting(sigma)
+
+    def __call__(self, network, input, sigma, cond):
+        sigma = self.possibly_quantize_sigma(sigma)
+        sigma_shape = sigma.shape
+        sigma = append_dims(sigma, input.ndim)
+        c_skip, c_out, c_in, c_noise = self.scaling(sigma)
+        c_noise = self.possibly_quantize_c_noise(c_noise.reshape(sigma_shape))
+        return network(input * c_in, c_noise, cond) * c_out + input * c_skip
+
+
+class DiscreteDenoiser(Denoiser):
+    def __init__(
+        self,
+        weighting_config,
+        scaling_config,
+        num_idx,
+        discretization_config,
+        do_append_zero=False,
+        quantize_c_noise=True,
+        flip=True,
+    ):
+        super().__init__(weighting_config, scaling_config)
+        sigmas = instantiate_from_config(discretization_config)(
+            num_idx, do_append_zero=do_append_zero, flip=flip
+        )
+        self.register_buffer("sigmas", sigmas)
+        self.quantize_c_noise = quantize_c_noise
+
+    def sigma_to_idx(self, sigma):
+        dists = sigma - self.sigmas[:, None]
+        return dists.abs().argmin(dim=0).view(sigma.shape)
+
+    def idx_to_sigma(self, idx):
+        return self.sigmas[idx]
+
+    def possibly_quantize_sigma(self, sigma):
+        return self.idx_to_sigma(self.sigma_to_idx(sigma))
+
+    def possibly_quantize_c_noise(self, c_noise):
+        if self.quantize_c_noise:
+            return self.sigma_to_idx(c_noise)
+        else:
+            return c_noise

sgm/modules/diffusionmodules/denoiser_scaling.py

@@ -0,0 +1,31 @@
+import torch
+
+
+class EDMScaling:
+    def __init__(self, sigma_data=0.5):
+        self.sigma_data = sigma_data
+
+    def __call__(self, sigma):
+        c_skip = self.sigma_data**2 / (sigma**2 + self.sigma_data**2)
+        c_out = sigma * self.sigma_data / (sigma**2 + self.sigma_data**2) ** 0.5
+        c_in = 1 / (sigma**2 + self.sigma_data**2) ** 0.5
+        c_noise = 0.25 * sigma.log()
+        return c_skip, c_out, c_in, c_noise
+
+
+class EpsScaling:
+    def __call__(self, sigma):
+        c_skip = torch.ones_like(sigma, device=sigma.device)
+        c_out = -sigma
+        c_in = 1 / (sigma**2 + 1.0) ** 0.5
+        c_noise = sigma.clone()
+        return c_skip, c_out, c_in, c_noise
+
+
+class VScaling:
+    def __call__(self, sigma):
+        c_skip = 1.0 / (sigma**2 + 1.0)
+        c_out = -sigma / (sigma**2 + 1.0) ** 0.5
+        c_in = 1.0 / (sigma**2 + 1.0) ** 0.5
+        c_noise = sigma.clone()
+        return c_skip, c_out, c_in, c_noise

sgm/modules/diffusionmodules/denoiser_weighting.py

@@ -0,0 +1,24 @@
+import torch
+
+
+class UnitWeighting:
+    def __call__(self, sigma):
+        return torch.ones_like(sigma, device=sigma.device)
+
+
+class EDMWeighting:
+    def __init__(self, sigma_data=0.5):
+        self.sigma_data = sigma_data
+
+    def __call__(self, sigma):
+        return (sigma**2 + self.sigma_data**2) / (sigma * self.sigma_data) ** 2
+
+
+class VWeighting(EDMWeighting):
+    def __init__(self):
+        super().__init__(sigma_data=1.0)
+
+
+class EpsWeighting:
+    def __call__(self, sigma):
+        return sigma**-2.0

sgm/modules/diffusionmodules/discretizer.py

@@ -0,0 +1,65 @@
+import torch
+import numpy as np
+from functools import partial
+
+from ...util import append_zero
+from ...modules.diffusionmodules.util import make_beta_schedule
+
+
+class Discretization:
+    def __call__(self, n, do_append_zero=True, device="cuda", flip=False):
+        sigmas = self.get_sigmas(n, device)
+        sigmas = append_zero(sigmas) if do_append_zero else sigmas
+        return sigmas if not flip else torch.flip(sigmas, (0,))
+
+
+class EDMDiscretization(Discretization):
+    def __init__(self, sigma_min=0.02, sigma_max=80.0, rho=7.0):
+        self.sigma_min = sigma_min
+        self.sigma_max = sigma_max
+        self.rho = rho
+
+    def get_sigmas(self, n, device):
+        ramp = torch.linspace(0, 1, n, device=device)
+        min_inv_rho = self.sigma_min ** (1 / self.rho)
+        max_inv_rho = self.sigma_max ** (1 / self.rho)
+        sigmas = (max_inv_rho + ramp * (min_inv_rho - max_inv_rho)) ** self.rho
+        return sigmas
+
+
+class LegacyDDPMDiscretization(Discretization):
+    def __init__(
+        self,
+        linear_start=0.00085,
+        linear_end=0.0120,
+        num_timesteps=1000,
+        legacy_range=True,
+    ):
+        self.num_timesteps = num_timesteps
+        betas = make_beta_schedule(
+            "linear", num_timesteps, linear_start=linear_start, linear_end=linear_end
+        )
+        alphas = 1.0 - betas
+        self.alphas_cumprod = np.cumprod(alphas, axis=0)
+        self.to_torch = partial(torch.tensor, dtype=torch.float32)
+        self.legacy_range = legacy_range
+
+    def get_sigmas(self, n, device):
+        if n < self.num_timesteps:
+            c = self.num_timesteps // n
+
+            if self.legacy_range:
+                timesteps = np.asarray(list(range(0, self.num_timesteps, c)))
+                timesteps += 1  # Legacy LDM Hack
+            else:
+                timesteps = np.asarray(list(range(0, self.num_timesteps + 1, c)))
+                timesteps -= 1
+                timesteps = timesteps[1:]
+
+            alphas_cumprod = self.alphas_cumprod[timesteps]
+        else:
+            alphas_cumprod = self.alphas_cumprod
+
+        to_torch = partial(torch.tensor, dtype=torch.float32, device=device)
+        sigmas = to_torch((1 - alphas_cumprod) / alphas_cumprod) ** 0.5
+        return torch.flip(sigmas, (0,))

sgm/modules/diffusionmodules/guiders.py

@@ -0,0 +1,53 @@
+from functools import partial
+
+import torch
+
+from ...util import default, instantiate_from_config
+
+
+class VanillaCFG:
+    """
+    implements parallelized CFG
+    """
+
+    def __init__(self, scale, dyn_thresh_config=None):
+        scale_schedule = lambda scale, sigma: scale  # independent of step
+        self.scale_schedule = partial(scale_schedule, scale)
+        self.dyn_thresh = instantiate_from_config(
+            default(
+                dyn_thresh_config,
+                {
+                    "target": "sgm.modules.diffusionmodules.sampling_utils.NoDynamicThresholding"
+                },
+            )
+        )
+
+    def __call__(self, x, sigma):
+        x_u, x_c = x.chunk(2)
+        scale_value = self.scale_schedule(sigma)
+        x_pred = self.dyn_thresh(x_u, x_c, scale_value)
+        return x_pred
+
+    def prepare_inputs(self, x, s, c, uc):
+        c_out = dict()
+
+        for k in c:
+            if k in ["vector", "crossattn", "concat"]:
+                c_out[k] = torch.cat((uc[k], c[k]), 0)
+            else:
+                assert c[k] == uc[k]
+                c_out[k] = c[k]
+        return torch.cat([x] * 2), torch.cat([s] * 2), c_out
+
+
+class IdentityGuider:
+    def __call__(self, x, sigma):
+        return x
+
+    def prepare_inputs(self, x, s, c, uc):
+        c_out = dict()
+
+        for k in c:
+            c_out[k] = c[k]
+
+        return x, s, c_out

sgm/modules/diffusionmodules/loss.py

@@ -0,0 +1,69 @@
+from typing import List, Optional, Union
+
+import torch
+import torch.nn as nn
+from omegaconf import ListConfig
+from taming.modules.losses.lpips import LPIPS
+
+from ...util import append_dims, instantiate_from_config
+
+
+class StandardDiffusionLoss(nn.Module):
+    def __init__(
+        self,
+        sigma_sampler_config,
+        type="l2",
+        offset_noise_level=0.0,
+        batch2model_keys: Optional[Union[str, List[str], ListConfig]] = None,
+    ):
+        super().__init__()
+
+        assert type in ["l2", "l1", "lpips"]
+
+        self.sigma_sampler = instantiate_from_config(sigma_sampler_config)
+
+        self.type = type
+        self.offset_noise_level = offset_noise_level
+
+        if type == "lpips":
+            self.lpips = LPIPS().eval()
+
+        if not batch2model_keys:
+            batch2model_keys = []
+
+        if isinstance(batch2model_keys, str):
+            batch2model_keys = [batch2model_keys]
+
+        self.batch2model_keys = set(batch2model_keys)
+
+    def __call__(self, network, denoiser, conditioner, input, batch):
+        cond = conditioner(batch)
+        additional_model_inputs = {
+            key: batch[key] for key in self.batch2model_keys.intersection(batch)
+        }
+
+        sigmas = self.sigma_sampler(input.shape[0]).to(input.device)
+        noise = torch.randn_like(input)
+        if self.offset_noise_level > 0.0:
+            noise = noise + self.offset_noise_level * append_dims(
+                torch.randn(input.shape[0], device=input.device), input.ndim
+            )
+        noised_input = input + noise * append_dims(sigmas, input.ndim)
+        model_output = denoiser(
+            network, noised_input, sigmas, cond, **additional_model_inputs
+        )
+        w = append_dims(denoiser.w(sigmas), input.ndim)
+        return self.get_loss(model_output, input, w)
+
+    def get_loss(self, model_output, target, w):
+        if self.type == "l2":
+            return torch.mean(
+                (w * (model_output - target) ** 2).reshape(target.shape[0], -1), 1
+            )
+        elif self.type == "l1":
+            return torch.mean(
+                (w * (model_output - target).abs()).reshape(target.shape[0], -1), 1
+            )
+        elif self.type == "lpips":
+            loss = self.lpips(model_output, target).reshape(-1)
+            return loss

sgm/modules/diffusionmodules/model.py

@@ -0,0 +1,743 @@
+# pytorch_diffusion + derived encoder decoder
+import math
+from typing import Any, Callable, Optional
+
+import numpy as np
+import torch
+import torch.nn as nn
+from einops import rearrange
+from packaging import version
+
+try:
+    import xformers
+    import xformers.ops
+
+    XFORMERS_IS_AVAILABLE = True
+except:
+    XFORMERS_IS_AVAILABLE = False
+    print("no module 'xformers'. Processing without...")
+
+from ...modules.attention import LinearAttention, MemoryEfficientCrossAttention
+
+
+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
+
+
+def nonlinearity(x):
+    # swish
+    return x * torch.sigmoid(x)
+
+
+def Normalize(in_channels, num_groups=32):
+    return torch.nn.GroupNorm(
+        num_groups=num_groups, num_channels=in_channels, eps=1e-6, affine=True
+    )
+
+
+class Upsample(nn.Module):
+    def __init__(self, in_channels, with_conv):
+        super().__init__()
+        self.with_conv = with_conv
+        if self.with_conv:
+            self.conv = torch.nn.Conv2d(
+                in_channels, in_channels, kernel_size=3, stride=1, padding=1
+            )
+
+    def forward(self, x):
+        x = torch.nn.functional.interpolate(x, scale_factor=2.0, mode="nearest")
+        if self.with_conv:
+            x = self.conv(x)
+        return x
+
+
+class Downsample(nn.Module):
+    def __init__(self, in_channels, with_conv):
+        super().__init__()
+        self.with_conv = with_conv
+        if self.with_conv:
+            # no asymmetric padding in torch conv, must do it ourselves
+            self.conv = torch.nn.Conv2d(
+                in_channels, in_channels, kernel_size=3, stride=2, padding=0
+            )
+
+    def forward(self, x):
+        if self.with_conv:
+            pad = (0, 1, 0, 1)
+            x = torch.nn.functional.pad(x, pad, mode="constant", value=0)
+            x = self.conv(x)
+        else:
+            x = torch.nn.functional.avg_pool2d(x, kernel_size=2, stride=2)
+        return x
+
+
+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 LinAttnBlock(LinearAttention):
+    """to match AttnBlock usage"""
+
+    def __init__(self, in_channels):
+        super().__init__(dim=in_channels, heads=1, dim_head=in_channels)
+
+
+class AttnBlock(nn.Module):
+    def __init__(self, in_channels):
+        super().__init__()
+        self.in_channels = in_channels
+
+        self.norm = Normalize(in_channels)
+        self.q = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+        self.k = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+        self.v = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+        self.proj_out = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+
+    def attention(self, h_: torch.Tensor) -> torch.Tensor:
+        h_ = self.norm(h_)
+        q = self.q(h_)
+        k = self.k(h_)
+        v = self.v(h_)
+
+        b, c, h, w = q.shape
+        q, k, v = map(
+            lambda x: rearrange(x, "b c h w -> b 1 (h w) c").contiguous(), (q, k, v)
+        )
+        h_ = torch.nn.functional.scaled_dot_product_attention(
+            q, k, v
+        )  # scale is dim ** -0.5 per default
+        # compute attention
+
+        return rearrange(h_, "b 1 (h w) c -> b c h w", h=h, w=w, c=c, b=b)
+
+    def forward(self, x, **kwargs):
+        h_ = x
+        h_ = self.attention(h_)
+        h_ = self.proj_out(h_)
+        return x + h_
+
+
+class MemoryEfficientAttnBlock(nn.Module):
+    """
+    Uses xformers efficient implementation,
+    see https://github.com/MatthieuTPHR/diffusers/blob/d80b531ff8060ec1ea982b65a1b8df70f73aa67c/src/diffusers/models/attention.py#L223
+    Note: this is a single-head self-attention operation
+    """
+
+    #
+    def __init__(self, in_channels):
+        super().__init__()
+        self.in_channels = in_channels
+
+        self.norm = Normalize(in_channels)
+        self.q = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+        self.k = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+        self.v = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+        self.proj_out = torch.nn.Conv2d(
+            in_channels, in_channels, kernel_size=1, stride=1, padding=0
+        )
+        self.attention_op: Optional[Any] = None
+
+    def attention(self, h_: torch.Tensor) -> torch.Tensor:
+        h_ = self.norm(h_)
+        q = self.q(h_)
+        k = self.k(h_)
+        v = self.v(h_)
+
+        # compute attention
+        B, C, H, W = q.shape
+        q, k, v = map(lambda x: rearrange(x, "b c h w -> b (h w) c"), (q, k, v))
+
+        q, k, v = map(
+            lambda t: t.unsqueeze(3)
+            .reshape(B, t.shape[1], 1, C)
+            .permute(0, 2, 1, 3)
+            .reshape(B * 1, t.shape[1], C)
+            .contiguous(),
+            (q, k, v),
+        )
+        out = xformers.ops.memory_efficient_attention(
+            q, k, v, attn_bias=None, op=self.attention_op
+        )
+
+        out = (
+            out.unsqueeze(0)
+            .reshape(B, 1, out.shape[1], C)
+            .permute(0, 2, 1, 3)
+            .reshape(B, out.shape[1], C)
+        )
+        return rearrange(out, "b (h w) c -> b c h w", b=B, h=H, w=W, c=C)
+
+    def forward(self, x, **kwargs):
+        h_ = x
+        h_ = self.attention(h_)
+        h_ = self.proj_out(h_)
+        return x + h_
+
+
+class MemoryEfficientCrossAttentionWrapper(MemoryEfficientCrossAttention):
+    def forward(self, x, context=None, mask=None, **unused_kwargs):
+        b, c, h, w = x.shape
+        x = rearrange(x, "b c h w -> b (h w) c")
+        out = super().forward(x, context=context, mask=mask)
+        out = rearrange(out, "b (h w) c -> b c h w", h=h, w=w, c=c)
+        return x + out
+
+
+def make_attn(in_channels, attn_type="vanilla", attn_kwargs=None):
+    assert attn_type in [
+        "vanilla",
+        "vanilla-xformers",
+        "memory-efficient-cross-attn",
+        "linear",
+        "none",
+    ], f"attn_type {attn_type} unknown"
+    if (
+        version.parse(torch.__version__) < version.parse("2.0.0")
+        and attn_type != "none"
+    ):
+        assert XFORMERS_IS_AVAILABLE, (
+            f"We do not support vanilla attention in {torch.__version__} anymore, "
+            f"as it is too expensive. Please install xformers via e.g. 'pip install xformers==0.0.16'"
+        )
+        attn_type = "vanilla-xformers"
+    print(f"making attention of type '{attn_type}' with {in_channels} in_channels")
+    if attn_type == "vanilla":
+        assert attn_kwargs is None
+        return AttnBlock(in_channels)
+    elif attn_type == "vanilla-xformers":
+        print(f"building MemoryEfficientAttnBlock with {in_channels} in_channels...")
+        return MemoryEfficientAttnBlock(in_channels)
+    elif type == "memory-efficient-cross-attn":
+        attn_kwargs["query_dim"] = in_channels
+        return MemoryEfficientCrossAttentionWrapper(**attn_kwargs)
+    elif attn_type == "none":
+        return nn.Identity(in_channels)
+    else:
+        return LinAttnBlock(in_channels)
+
+
+class Model(nn.Module):
+    def __init__(
+        self,
+        *,
+        ch,
+        out_ch,
+        ch_mult=(1, 2, 4, 8),
+        num_res_blocks,
+        attn_resolutions,
+        dropout=0.0,
+        resamp_with_conv=True,
+        in_channels,
+        resolution,
+        use_timestep=True,
+        use_linear_attn=False,
+        attn_type="vanilla",
+    ):
+        super().__init__()
+        if use_linear_attn:
+            attn_type = "linear"
+        self.ch = ch
+        self.temb_ch = self.ch * 4
+        self.num_resolutions = len(ch_mult)
+        self.num_res_blocks = num_res_blocks
+        self.resolution = resolution
+        self.in_channels = in_channels
+
+        self.use_timestep = use_timestep
+        if self.use_timestep:
+            # timestep embedding
+            self.temb = nn.Module()
+            self.temb.dense = nn.ModuleList(
+                [
+                    torch.nn.Linear(self.ch, self.temb_ch),
+                    torch.nn.Linear(self.temb_ch, self.temb_ch),
+                ]
+            )
+
+        # downsampling
+        self.conv_in = torch.nn.Conv2d(
+            in_channels, self.ch, kernel_size=3, stride=1, padding=1
+        )
+
+        curr_res = resolution
+        in_ch_mult = (1,) + tuple(ch_mult)
+        self.down = nn.ModuleList()
+        for i_level in range(self.num_resolutions):
+            block = nn.ModuleList()
+            attn = nn.ModuleList()
+            block_in = ch * in_ch_mult[i_level]
+            block_out = ch * ch_mult[i_level]
+            for i_block in range(self.num_res_blocks):
+                block.append(
+                    ResnetBlock(
+                        in_channels=block_in,
+                        out_channels=block_out,
+                        temb_channels=self.temb_ch,
+                        dropout=dropout,
+                    )
+                )
+                block_in = block_out
+                if curr_res in attn_resolutions:
+                    attn.append(make_attn(block_in, attn_type=attn_type))
+            down = nn.Module()
+            down.block = block
+            down.attn = attn
+            if i_level != self.num_resolutions - 1:
+                down.downsample = Downsample(block_in, resamp_with_conv)
+                curr_res = curr_res // 2
+            self.down.append(down)
+
+        # middle
+        self.mid = nn.Module()
+        self.mid.block_1 = ResnetBlock(
+            in_channels=block_in,
+            out_channels=block_in,
+            temb_channels=self.temb_ch,
+            dropout=dropout,
+        )
+        self.mid.attn_1 = make_attn(block_in, attn_type=attn_type)
+        self.mid.block_2 = ResnetBlock(
+            in_channels=block_in,
+            out_channels=block_in,
+            temb_channels=self.temb_ch,
+            dropout=dropout,
+        )
+
+        # upsampling
+        self.up = nn.ModuleList()
+        for i_level in reversed(range(self.num_resolutions)):
+            block = nn.ModuleList()
+            attn = nn.ModuleList()
+            block_out = ch * ch_mult[i_level]
+            skip_in = ch * ch_mult[i_level]
+            for i_block in range(self.num_res_blocks + 1):
+                if i_block == self.num_res_blocks:
+                    skip_in = ch * in_ch_mult[i_level]
+                block.append(
+                    ResnetBlock(
+                        in_channels=block_in + skip_in,
+                        out_channels=block_out,
+                        temb_channels=self.temb_ch,
+                        dropout=dropout,
+                    )
+                )
+                block_in = block_out
+                if curr_res in attn_resolutions:
+                    attn.append(make_attn(block_in, attn_type=attn_type))
+            up = nn.Module()
+            up.block = block
+            up.attn = attn
+            if i_level != 0:
+                up.upsample = Upsample(block_in, resamp_with_conv)
+                curr_res = curr_res * 2
+            self.up.insert(0, up)  # prepend to get consistent order
+
+        # end
+        self.norm_out = Normalize(block_in)
+        self.conv_out = torch.nn.Conv2d(
+            block_in, out_ch, kernel_size=3, stride=1, padding=1
+        )
+
+    def forward(self, x, t=None, context=None):
+        # assert x.shape[2] == x.shape[3] == self.resolution
+        if context is not None:
+            # assume aligned context, cat along channel axis
+            x = torch.cat((x, context), dim=1)
+        if self.use_timestep:
+            # timestep embedding
+            assert t is not None
+            temb = get_timestep_embedding(t, self.ch)
+            temb = self.temb.dense[0](temb)
+            temb = nonlinearity(temb)
+            temb = self.temb.dense[1](temb)
+        else:
+            temb = None
+
+        # downsampling
+        hs = [self.conv_in(x)]
+        for i_level in range(self.num_resolutions):
+            for i_block in range(self.num_res_blocks):
+                h = self.down[i_level].block[i_block](hs[-1], temb)
+                if len(self.down[i_level].attn) > 0:
+                    h = self.down[i_level].attn[i_block](h)
+                hs.append(h)
+            if i_level != self.num_resolutions - 1:
+                hs.append(self.down[i_level].downsample(hs[-1]))
+
+        # middle
+        h = hs[-1]
+        h = self.mid.block_1(h, temb)
+        h = self.mid.attn_1(h)
+        h = self.mid.block_2(h, temb)
+
+        # upsampling
+        for i_level in reversed(range(self.num_resolutions)):
+            for i_block in range(self.num_res_blocks + 1):
+                h = self.up[i_level].block[i_block](
+                    torch.cat([h, hs.pop()], dim=1), temb
+                )
+                if len(self.up[i_level].attn) > 0:
+                    h = self.up[i_level].attn[i_block](h)
+            if i_level != 0:
+                h = self.up[i_level].upsample(h)
+
+        # end
+        h = self.norm_out(h)
+        h = nonlinearity(h)
+        h = self.conv_out(h)
+        return h
+
+    def get_last_layer(self):
+        return self.conv_out.weight
+
+
+class Encoder(nn.Module):
+    def __init__(
+        self,
+        *,
+        ch,
+        out_ch,
+        ch_mult=(1, 2, 4, 8),
+        num_res_blocks,
+        attn_resolutions,
+        dropout=0.0,
+        resamp_with_conv=True,
+        in_channels,
+        resolution,
+        z_channels,
+        double_z=True,
+        use_linear_attn=False,
+        attn_type="vanilla",
+        **ignore_kwargs,
+    ):
+        super().__init__()
+        if use_linear_attn:
+            attn_type = "linear"
+        self.ch = ch
+        self.temb_ch = 0
+        self.num_resolutions = len(ch_mult)
+        self.num_res_blocks = num_res_blocks
+        self.resolution = resolution
+        self.in_channels = in_channels
+
+        # downsampling
+        self.conv_in = torch.nn.Conv2d(
+            in_channels, self.ch, kernel_size=3, stride=1, padding=1
+        )
+
+        curr_res = resolution
+        in_ch_mult = (1,) + tuple(ch_mult)
+        self.in_ch_mult = in_ch_mult
+        self.down = nn.ModuleList()
+        for i_level in range(self.num_resolutions):
+            block = nn.ModuleList()
+            attn = nn.ModuleList()
+            block_in = ch * in_ch_mult[i_level]
+            block_out = ch * ch_mult[i_level]
+            for i_block in range(self.num_res_blocks):
+                block.append(
+                    ResnetBlock(
+                        in_channels=block_in,
+                        out_channels=block_out,
+                        temb_channels=self.temb_ch,
+                        dropout=dropout,
+                    )
+                )
+                block_in = block_out
+                if curr_res in attn_resolutions:
+                    attn.append(make_attn(block_in, attn_type=attn_type))
+            down = nn.Module()
+            down.block = block
+            down.attn = attn
+            if i_level != self.num_resolutions - 1:
+                down.downsample = Downsample(block_in, resamp_with_conv)
+                curr_res = curr_res // 2
+            self.down.append(down)
+
+        # middle
+        self.mid = nn.Module()
+        self.mid.block_1 = ResnetBlock(
+            in_channels=block_in,
+            out_channels=block_in,
+            temb_channels=self.temb_ch,
+            dropout=dropout,
+        )
+        self.mid.attn_1 = make_attn(block_in, attn_type=attn_type)
+        self.mid.block_2 = ResnetBlock(
+            in_channels=block_in,
+            out_channels=block_in,
+            temb_channels=self.temb_ch,
+            dropout=dropout,
+        )
+
+        # end
+        self.norm_out = Normalize(block_in)
+        self.conv_out = torch.nn.Conv2d(
+            block_in,
+            2 * z_channels if double_z else z_channels,
+            kernel_size=3,
+            stride=1,
+            padding=1,
+        )
+
+    def forward(self, x):
+        # timestep embedding
+        temb = None
+
+        # downsampling
+        hs = [self.conv_in(x)]
+        for i_level in range(self.num_resolutions):
+            for i_block in range(self.num_res_blocks):
+                h = self.down[i_level].block[i_block](hs[-1], temb)
+                if len(self.down[i_level].attn) > 0:
+                    h = self.down[i_level].attn[i_block](h)
+                hs.append(h)
+            if i_level != self.num_resolutions - 1:
+                hs.append(self.down[i_level].downsample(hs[-1]))
+
+        # middle
+        h = hs[-1]
+        h = self.mid.block_1(h, temb)
+        h = self.mid.attn_1(h)
+        h = self.mid.block_2(h, temb)
+
+        # end
+        h = self.norm_out(h)
+        h = nonlinearity(h)
+        h = self.conv_out(h)
+        return h
+
+
+class Decoder(nn.Module):
+    def __init__(
+        self,
+        *,
+        ch,
+        out_ch,
+        ch_mult=(1, 2, 4, 8),
+        num_res_blocks,
+        attn_resolutions,
+        dropout=0.0,
+        resamp_with_conv=True,
+        in_channels,
+        resolution,
+        z_channels,
+        give_pre_end=False,
+        tanh_out=False,
+        use_linear_attn=False,
+        attn_type="vanilla",
+        **ignorekwargs,
+    ):
+        super().__init__()
+        if use_linear_attn:
+            attn_type = "linear"
+        self.ch = ch
+        self.temb_ch = 0
+        self.num_resolutions = len(ch_mult)
+        self.num_res_blocks = num_res_blocks
+        self.resolution = resolution
+        self.in_channels = in_channels
+        self.give_pre_end = give_pre_end
+        self.tanh_out = tanh_out
+
+        # compute in_ch_mult, block_in and curr_res at lowest res
+        in_ch_mult = (1,) + tuple(ch_mult)
+        block_in = ch * ch_mult[self.num_resolutions - 1]
+        curr_res = resolution // 2 ** (self.num_resolutions - 1)
+        self.z_shape = (1, z_channels, curr_res, curr_res)
+        print(
+            "Working with z of shape {} = {} dimensions.".format(
+                self.z_shape, np.prod(self.z_shape)
+            )
+        )
+
+        make_attn_cls = self._make_attn()
+        make_resblock_cls = self._make_resblock()
+        make_conv_cls = self._make_conv()
+        # z to block_in
+        self.conv_in = torch.nn.Conv2d(
+            z_channels, block_in, kernel_size=3, stride=1, padding=1
+        )
+
+        # middle
+        self.mid = nn.Module()
+        self.mid.block_1 = make_resblock_cls(
+            in_channels=block_in,
+            out_channels=block_in,
+            temb_channels=self.temb_ch,
+            dropout=dropout,
+        )
+        self.mid.attn_1 = make_attn_cls(block_in, attn_type=attn_type)
+        self.mid.block_2 = make_resblock_cls(
+            in_channels=block_in,
+            out_channels=block_in,
+            temb_channels=self.temb_ch,
+            dropout=dropout,
+        )
+
+        # upsampling
+        self.up = nn.ModuleList()
+        for i_level in reversed(range(self.num_resolutions)):
+            block = nn.ModuleList()
+            attn = nn.ModuleList()
+            block_out = ch * ch_mult[i_level]
+            for i_block in range(self.num_res_blocks + 1):
+                block.append(
+                    make_resblock_cls(
+                        in_channels=block_in,
+                        out_channels=block_out,
+                        temb_channels=self.temb_ch,
+                        dropout=dropout,
+                    )
+                )
+                block_in = block_out
+                if curr_res in attn_resolutions:
+                    attn.append(make_attn_cls(block_in, attn_type=attn_type))
+            up = nn.Module()
+            up.block = block
+            up.attn = attn
+            if i_level != 0:
+                up.upsample = Upsample(block_in, resamp_with_conv)
+                curr_res = curr_res * 2
+            self.up.insert(0, up)  # prepend to get consistent order
+
+        # end
+        self.norm_out = Normalize(block_in)
+        self.conv_out = make_conv_cls(
+            block_in, out_ch, kernel_size=3, stride=1, padding=1
+        )
+
+    def _make_attn(self) -> Callable:
+        return make_attn
+
+    def _make_resblock(self) -> Callable:
+        return ResnetBlock
+
+    def _make_conv(self) -> Callable:
+        return torch.nn.Conv2d
+
+    def get_last_layer(self, **kwargs):
+        return self.conv_out.weight
+
+    def forward(self, z, **kwargs):
+        # assert z.shape[1:] == self.z_shape[1:]
+        self.last_z_shape = z.shape
+
+        # timestep embedding
+        temb = None
+
+        # z to block_in
+        h = self.conv_in(z)
+
+        # middle
+        h = self.mid.block_1(h, temb, **kwargs)
+        h = self.mid.attn_1(h, **kwargs)
+        h = self.mid.block_2(h, temb, **kwargs)
+
+        # upsampling
+        for i_level in reversed(range(self.num_resolutions)):
+            for i_block in range(self.num_res_blocks + 1):
+                h = self.up[i_level].block[i_block](h, temb, **kwargs)
+                if len(self.up[i_level].attn) > 0:
+                    h = self.up[i_level].attn[i_block](h, **kwargs)
+            if i_level != 0:
+                h = self.up[i_level].upsample(h)
+
+        # end
+        if self.give_pre_end:
+            return h
+
+        h = self.norm_out(h)
+        h = nonlinearity(h)
+        h = self.conv_out(h, **kwargs)
+        if self.tanh_out:
+            h = torch.tanh(h)
+        return h

sgm/modules/diffusionmodules/sampling.py

@@ -0,0 +1,365 @@
+"""
+    Partially ported from https://github.com/crowsonkb/k-diffusion/blob/master/k_diffusion/sampling.py
+"""
+
+
+from typing import Dict, Union
+
+import torch
+from omegaconf import ListConfig, OmegaConf
+from tqdm import tqdm
+
+from ...modules.diffusionmodules.sampling_utils import (
+    get_ancestral_step,
+    linear_multistep_coeff,
+    to_d,
+    to_neg_log_sigma,
+    to_sigma,
+)
+from ...util import append_dims, default, instantiate_from_config
+
+DEFAULT_GUIDER = {"target": "sgm.modules.diffusionmodules.guiders.IdentityGuider"}
+
+
+class BaseDiffusionSampler:
+    def __init__(
+        self,
+        discretization_config: Union[Dict, ListConfig, OmegaConf],
+        num_steps: Union[int, None] = None,
+        guider_config: Union[Dict, ListConfig, OmegaConf, None] = None,
+        verbose: bool = False,
+        device: str = "cuda",
+    ):
+        self.num_steps = num_steps
+        self.discretization = instantiate_from_config(discretization_config)
+        self.guider = instantiate_from_config(
+            default(
+                guider_config,
+                DEFAULT_GUIDER,
+            )
+        )
+        self.verbose = verbose
+        self.device = device
+
+    def prepare_sampling_loop(self, x, cond, uc=None, num_steps=None):
+        sigmas = self.discretization(
+            self.num_steps if num_steps is None else num_steps, device=self.device
+        )
+        uc = default(uc, cond)
+
+        x *= torch.sqrt(1.0 + sigmas[0] ** 2.0)
+        num_sigmas = len(sigmas)
+
+        s_in = x.new_ones([x.shape[0]])
+
+        return x, s_in, sigmas, num_sigmas, cond, uc
+
+    def denoise(self, x, denoiser, sigma, cond, uc):
+        denoised = denoiser(*self.guider.prepare_inputs(x, sigma, cond, uc))
+        denoised = self.guider(denoised, sigma)
+        return denoised
+
+    def get_sigma_gen(self, num_sigmas):
+        sigma_generator = range(num_sigmas - 1)
+        if self.verbose:
+            print("#" * 30, " Sampling setting ", "#" * 30)
+            print(f"Sampler: {self.__class__.__name__}")
+            print(f"Discretization: {self.discretization.__class__.__name__}")
+            print(f"Guider: {self.guider.__class__.__name__}")
+            sigma_generator = tqdm(
+                sigma_generator,
+                total=num_sigmas,
+                desc=f"Sampling with {self.__class__.__name__} for {num_sigmas} steps",
+            )
+        return sigma_generator
+
+
+class SingleStepDiffusionSampler(BaseDiffusionSampler):
+    def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc, *args, **kwargs):
+        raise NotImplementedError
+
+    def euler_step(self, x, d, dt):
+        return x + dt * d
+
+
+class EDMSampler(SingleStepDiffusionSampler):
+    def __init__(
+        self, s_churn=0.0, s_tmin=0.0, s_tmax=float("inf"), s_noise=1.0, *args, **kwargs
+    ):
+        super().__init__(*args, **kwargs)
+
+        self.s_churn = s_churn
+        self.s_tmin = s_tmin
+        self.s_tmax = s_tmax
+        self.s_noise = s_noise
+
+    def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc=None, gamma=0.0):
+        sigma_hat = sigma * (gamma + 1.0)
+        if gamma > 0:
+            eps = torch.randn_like(x) * self.s_noise
+            x = x + eps * append_dims(sigma_hat**2 - sigma**2, x.ndim) ** 0.5
+
+        denoised = self.denoise(x, denoiser, sigma_hat, cond, uc)
+        d = to_d(x, sigma_hat, denoised)
+        dt = append_dims(next_sigma - sigma_hat, x.ndim)
+
+        euler_step = self.euler_step(x, d, dt)
+        x = self.possible_correction_step(
+            euler_step, x, d, dt, next_sigma, denoiser, cond, uc
+        )
+        return x
+
+    def __call__(self, denoiser, x, cond, uc=None, num_steps=None):
+        x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop(
+            x, cond, uc, num_steps
+        )
+
+        for i in self.get_sigma_gen(num_sigmas):
+            gamma = (
+                min(self.s_churn / (num_sigmas - 1), 2**0.5 - 1)
+                if self.s_tmin <= sigmas[i] <= self.s_tmax
+                else 0.0
+            )
+            x = self.sampler_step(
+                s_in * sigmas[i],
+                s_in * sigmas[i + 1],
+                denoiser,
+                x,
+                cond,
+                uc,
+                gamma,
+            )
+
+        return x
+
+
+class AncestralSampler(SingleStepDiffusionSampler):
+    def __init__(self, eta=1.0, s_noise=1.0, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.eta = eta
+        self.s_noise = s_noise
+        self.noise_sampler = lambda x: torch.randn_like(x)
+
+    def ancestral_euler_step(self, x, denoised, sigma, sigma_down):
+        d = to_d(x, sigma, denoised)
+        dt = append_dims(sigma_down - sigma, x.ndim)
+
+        return self.euler_step(x, d, dt)
+
+    def ancestral_step(self, x, sigma, next_sigma, sigma_up):
+        x = torch.where(
+            append_dims(next_sigma, x.ndim) > 0.0,
+            x + self.noise_sampler(x) * self.s_noise * append_dims(sigma_up, x.ndim),
+            x,
+        )
+        return x
+
+    def __call__(self, denoiser, x, cond, uc=None, num_steps=None):
+        x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop(
+            x, cond, uc, num_steps
+        )
+
+        for i in self.get_sigma_gen(num_sigmas):
+            x = self.sampler_step(
+                s_in * sigmas[i],
+                s_in * sigmas[i + 1],
+                denoiser,
+                x,
+                cond,
+                uc,
+            )
+
+        return x
+
+
+class LinearMultistepSampler(BaseDiffusionSampler):
+    def __init__(
+        self,
+        order=4,
+        *args,
+        **kwargs,
+    ):
+        super().__init__(*args, **kwargs)
+
+        self.order = order
+
+    def __call__(self, denoiser, x, cond, uc=None, num_steps=None, **kwargs):
+        x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop(
+            x, cond, uc, num_steps
+        )
+
+        ds = []
+        sigmas_cpu = sigmas.detach().cpu().numpy()
+        for i in self.get_sigma_gen(num_sigmas):
+            sigma = s_in * sigmas[i]
+            denoised = denoiser(
+                *self.guider.prepare_inputs(x, sigma, cond, uc), **kwargs
+            )
+            denoised = self.guider(denoised, sigma)
+            d = to_d(x, sigma, denoised)
+            ds.append(d)
+            if len(ds) > self.order:
+                ds.pop(0)
+            cur_order = min(i + 1, self.order)
+            coeffs = [
+                linear_multistep_coeff(cur_order, sigmas_cpu, i, j)
+                for j in range(cur_order)
+            ]
+            x = x + sum(coeff * d for coeff, d in zip(coeffs, reversed(ds)))
+
+        return x
+
+
+class EulerEDMSampler(EDMSampler):
+    def possible_correction_step(
+        self, euler_step, x, d, dt, next_sigma, denoiser, cond, uc
+    ):
+        return euler_step
+
+
+class HeunEDMSampler(EDMSampler):
+    def possible_correction_step(
+        self, euler_step, x, d, dt, next_sigma, denoiser, cond, uc
+    ):
+        if torch.sum(next_sigma) < 1e-14:
+            # Save a network evaluation if all noise levels are 0
+            return euler_step
+        else:
+            denoised = self.denoise(euler_step, denoiser, next_sigma, cond, uc)
+            d_new = to_d(euler_step, next_sigma, denoised)
+            d_prime = (d + d_new) / 2.0
+
+            # apply correction if noise level is not 0
+            x = torch.where(
+                append_dims(next_sigma, x.ndim) > 0.0, x + d_prime * dt, euler_step
+            )
+            return x
+
+
+class EulerAncestralSampler(AncestralSampler):
+    def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc):
+        sigma_down, sigma_up = get_ancestral_step(sigma, next_sigma, eta=self.eta)
+        denoised = self.denoise(x, denoiser, sigma, cond, uc)
+        x = self.ancestral_euler_step(x, denoised, sigma, sigma_down)
+        x = self.ancestral_step(x, sigma, next_sigma, sigma_up)
+
+        return x
+
+
+class DPMPP2SAncestralSampler(AncestralSampler):
+    def get_variables(self, sigma, sigma_down):
+        t, t_next = [to_neg_log_sigma(s) for s in (sigma, sigma_down)]
+        h = t_next - t
+        s = t + 0.5 * h
+        return h, s, t, t_next
+
+    def get_mult(self, h, s, t, t_next):
+        mult1 = to_sigma(s) / to_sigma(t)
+        mult2 = (-0.5 * h).expm1()
+        mult3 = to_sigma(t_next) / to_sigma(t)
+        mult4 = (-h).expm1()
+
+        return mult1, mult2, mult3, mult4
+
+    def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc=None, **kwargs):
+        sigma_down, sigma_up = get_ancestral_step(sigma, next_sigma, eta=self.eta)
+        denoised = self.denoise(x, denoiser, sigma, cond, uc)
+        x_euler = self.ancestral_euler_step(x, denoised, sigma, sigma_down)
+
+        if torch.sum(sigma_down) < 1e-14:
+            # Save a network evaluation if all noise levels are 0
+            x = x_euler
+        else:
+            h, s, t, t_next = self.get_variables(sigma, sigma_down)
+            mult = [
+                append_dims(mult, x.ndim) for mult in self.get_mult(h, s, t, t_next)
+            ]
+
+            x2 = mult[0] * x - mult[1] * denoised
+            denoised2 = self.denoise(x2, denoiser, to_sigma(s), cond, uc)
+            x_dpmpp2s = mult[2] * x - mult[3] * denoised2
+
+            # apply correction if noise level is not 0
+            x = torch.where(append_dims(sigma_down, x.ndim) > 0.0, x_dpmpp2s, x_euler)
+
+        x = self.ancestral_step(x, sigma, next_sigma, sigma_up)
+        return x
+
+
+class DPMPP2MSampler(BaseDiffusionSampler):
+    def get_variables(self, sigma, next_sigma, previous_sigma=None):
+        t, t_next = [to_neg_log_sigma(s) for s in (sigma, next_sigma)]
+        h = t_next - t
+
+        if previous_sigma is not None:
+            h_last = t - to_neg_log_sigma(previous_sigma)
+            r = h_last / h
+            return h, r, t, t_next
+        else:
+            return h, None, t, t_next
+
+    def get_mult(self, h, r, t, t_next, previous_sigma):
+        mult1 = to_sigma(t_next) / to_sigma(t)
+        mult2 = (-h).expm1()
+
+        if previous_sigma is not None:
+            mult3 = 1 + 1 / (2 * r)
+            mult4 = 1 / (2 * r)
+            return mult1, mult2, mult3, mult4
+        else:
+            return mult1, mult2
+
+    def sampler_step(
+        self,
+        old_denoised,
+        previous_sigma,
+        sigma,
+        next_sigma,
+        denoiser,
+        x,
+        cond,
+        uc=None,
+    ):
+        denoised = self.denoise(x, denoiser, sigma, cond, uc)
+
+        h, r, t, t_next = self.get_variables(sigma, next_sigma, previous_sigma)
+        mult = [
+            append_dims(mult, x.ndim)
+            for mult in self.get_mult(h, r, t, t_next, previous_sigma)
+        ]
+
+        x_standard = mult[0] * x - mult[1] * denoised
+        if old_denoised is None or torch.sum(next_sigma) < 1e-14:
+            # Save a network evaluation if all noise levels are 0 or on the first step
+            return x_standard, denoised
+        else:
+            denoised_d = mult[2] * denoised - mult[3] * old_denoised
+            x_advanced = mult[0] * x - mult[1] * denoised_d
+
+            # apply correction if noise level is not 0 and not first step
+            x = torch.where(
+                append_dims(next_sigma, x.ndim) > 0.0, x_advanced, x_standard
+            )
+
+        return x, denoised
+
+    def __call__(self, denoiser, x, cond, uc=None, num_steps=None, **kwargs):
+        x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop(
+            x, cond, uc, num_steps
+        )
+
+        old_denoised = None
+        for i in self.get_sigma_gen(num_sigmas):
+            x, old_denoised = self.sampler_step(
+                old_denoised,
+                None if i == 0 else s_in * sigmas[i - 1],
+                s_in * sigmas[i],
+                s_in * sigmas[i + 1],
+                denoiser,
+                x,
+                cond,
+                uc=uc,
+            )
+
+        return x

sgm/modules/diffusionmodules/sampling_utils.py

@@ -0,0 +1,48 @@
+import torch
+from scipy import integrate
+
+from ...util import append_dims
+
+
+class NoDynamicThresholding:
+    def __call__(self, uncond, cond, scale):
+        return uncond + scale * (cond - uncond)
+
+
+def linear_multistep_coeff(order, t, i, j, epsrel=1e-4):
+    if order - 1 > i:
+        raise ValueError(f"Order {order} too high for step {i}")
+
+    def fn(tau):
+        prod = 1.0
+        for k in range(order):
+            if j == k:
+                continue
+            prod *= (tau - t[i - k]) / (t[i - j] - t[i - k])
+        return prod
+
+    return integrate.quad(fn, t[i], t[i + 1], epsrel=epsrel)[0]
+
+
+def get_ancestral_step(sigma_from, sigma_to, eta=1.0):
+    if not eta:
+        return sigma_to, 0.0
+    sigma_up = torch.minimum(
+        sigma_to,
+        eta
+        * (sigma_to**2 * (sigma_from**2 - sigma_to**2) / sigma_from**2) ** 0.5,
+    )
+    sigma_down = (sigma_to**2 - sigma_up**2) ** 0.5
+    return sigma_down, sigma_up
+
+
+def to_d(x, sigma, denoised):
+    return (x - denoised) / append_dims(sigma, x.ndim)
+
+
+def to_neg_log_sigma(sigma):
+    return sigma.log().neg()
+
+
+def to_sigma(neg_log_sigma):
+    return neg_log_sigma.neg().exp()

sgm/modules/diffusionmodules/sigma_sampling.py

@@ -0,0 +1,31 @@
+import torch
+
+from ...util import default, instantiate_from_config
+
+
+class EDMSampling:
+    def __init__(self, p_mean=-1.2, p_std=1.2):
+        self.p_mean = p_mean
+        self.p_std = p_std
+
+    def __call__(self, n_samples, rand=None):
+        log_sigma = self.p_mean + self.p_std * default(rand, torch.randn((n_samples,)))
+        return log_sigma.exp()
+
+
+class DiscreteSampling:
+    def __init__(self, discretization_config, num_idx, do_append_zero=False, flip=True):
+        self.num_idx = num_idx
+        self.sigmas = instantiate_from_config(discretization_config)(
+            num_idx, do_append_zero=do_append_zero, flip=flip
+        )
+
+    def idx_to_sigma(self, idx):
+        return self.sigmas[idx]
+
+    def __call__(self, n_samples, rand=None):
+        idx = default(
+            rand,
+            torch.randint(0, self.num_idx, (n_samples,)),
+        )
+        return self.idx_to_sigma(idx)

sgm/modules/diffusionmodules/util.py

@@ -0,0 +1,308 @@
+"""
+adopted from
+https://github.com/openai/improved-diffusion/blob/main/improved_diffusion/gaussian_diffusion.py
+and
+https://github.com/lucidrains/denoising-diffusion-pytorch/blob/7706bdfc6f527f58d33f84b7b522e61e6e3164b3/denoising_diffusion_pytorch/denoising_diffusion_pytorch.py
+and
+https://github.com/openai/guided-diffusion/blob/0ba878e517b276c45d1195eb29f6f5f72659a05b/guided_diffusion/nn.py
+
+thanks!
+"""
+
+import math
+
+import torch
+import torch.nn as nn
+from einops import repeat
+
+
+def make_beta_schedule(
+    schedule,
+    n_timestep,
+    linear_start=1e-4,
+    linear_end=2e-2,
+):
+    if schedule == "linear":
+        betas = (
+            torch.linspace(
+                linear_start**0.5, linear_end**0.5, n_timestep, dtype=torch.float64
+            )
+            ** 2
+        )
+    return betas.numpy()
+
+
+def extract_into_tensor(a, t, x_shape):
+    b, *_ = t.shape
+    out = a.gather(-1, t)
+    return out.reshape(b, *((1,) * (len(x_shape) - 1)))
+
+
+def mixed_checkpoint(func, inputs: dict, params, flag):
+    """
+    Evaluate a function without caching intermediate activations, allowing for
+    reduced memory at the expense of extra compute in the backward pass. This differs from the original checkpoint function
+    borrowed from https://github.com/openai/guided-diffusion/blob/0ba878e517b276c45d1195eb29f6f5f72659a05b/guided_diffusion/nn.py in that
+    it also works with non-tensor inputs
+    :param func: the function to evaluate.
+    :param inputs: the argument dictionary to pass to `func`.
+    :param params: a sequence of parameters `func` depends on but does not
+                   explicitly take as arguments.
+    :param flag: if False, disable gradient checkpointing.
+    """
+    if flag:
+        tensor_keys = [key for key in inputs if isinstance(inputs[key], torch.Tensor)]
+        tensor_inputs = [
+            inputs[key] for key in inputs if isinstance(inputs[key], torch.Tensor)
+        ]
+        non_tensor_keys = [
+            key for key in inputs if not isinstance(inputs[key], torch.Tensor)
+        ]
+        non_tensor_inputs = [
+            inputs[key] for key in inputs if not isinstance(inputs[key], torch.Tensor)
+        ]
+        args = tuple(tensor_inputs) + tuple(non_tensor_inputs) + tuple(params)
+        return MixedCheckpointFunction.apply(
+            func,
+            len(tensor_inputs),
+            len(non_tensor_inputs),
+            tensor_keys,
+            non_tensor_keys,
+            *args,
+        )
+    else:
+        return func(**inputs)
+
+
+class MixedCheckpointFunction(torch.autograd.Function):
+    @staticmethod
+    def forward(
+        ctx,
+        run_function,
+        length_tensors,
+        length_non_tensors,
+        tensor_keys,
+        non_tensor_keys,
+        *args,
+    ):
+        ctx.end_tensors = length_tensors
+        ctx.end_non_tensors = length_tensors + length_non_tensors
+        ctx.gpu_autocast_kwargs = {
+            "enabled": torch.is_autocast_enabled(),
+            "dtype": torch.get_autocast_gpu_dtype(),
+            "cache_enabled": torch.is_autocast_cache_enabled(),
+        }
+        assert (
+            len(tensor_keys) == length_tensors
+            and len(non_tensor_keys) == length_non_tensors
+        )
+
+        ctx.input_tensors = {
+            key: val for (key, val) in zip(tensor_keys, list(args[: ctx.end_tensors]))
+        }
+        ctx.input_non_tensors = {
+            key: val
+            for (key, val) in zip(
+                non_tensor_keys, list(args[ctx.end_tensors : ctx.end_non_tensors])
+            )
+        }
+        ctx.run_function = run_function
+        ctx.input_params = list(args[ctx.end_non_tensors :])
+
+        with torch.no_grad():
+            output_tensors = ctx.run_function(
+                **ctx.input_tensors, **ctx.input_non_tensors
+            )
+        return output_tensors
+
+    @staticmethod
+    def backward(ctx, *output_grads):
+        # additional_args = {key: ctx.input_tensors[key] for key in ctx.input_tensors if not isinstance(ctx.input_tensors[key],torch.Tensor)}
+        ctx.input_tensors = {
+            key: ctx.input_tensors[key].detach().requires_grad_(True)
+            for key in ctx.input_tensors
+        }
+
+        with torch.enable_grad(), torch.cuda.amp.autocast(**ctx.gpu_autocast_kwargs):
+            # Fixes a bug where the first op in run_function modifies the
+            # Tensor storage in place, which is not allowed for detach()'d
+            # Tensors.
+            shallow_copies = {
+                key: ctx.input_tensors[key].view_as(ctx.input_tensors[key])
+                for key in ctx.input_tensors
+            }
+            # shallow_copies.update(additional_args)
+            output_tensors = ctx.run_function(**shallow_copies, **ctx.input_non_tensors)
+        input_grads = torch.autograd.grad(
+            output_tensors,
+            list(ctx.input_tensors.values()) + ctx.input_params,
+            output_grads,
+            allow_unused=True,
+        )
+        del ctx.input_tensors
+        del ctx.input_params
+        del output_tensors
+        return (
+            (None, None, None, None, None)
+            + input_grads[: ctx.end_tensors]
+            + (None,) * (ctx.end_non_tensors - ctx.end_tensors)
+            + input_grads[ctx.end_tensors :]
+        )
+
+
+def checkpoint(func, inputs, params, flag):
+    """
+    Evaluate a function without caching intermediate activations, allowing for
+    reduced memory at the expense of extra compute in the backward pass.
+    :param func: the function to evaluate.
+    :param inputs: the argument sequence to pass to `func`.
+    :param params: a sequence of parameters `func` depends on but does not
+                   explicitly take as arguments.
+    :param flag: if False, disable gradient checkpointing.
+    """
+    if flag:
+        args = tuple(inputs) + tuple(params)
+        return CheckpointFunction.apply(func, len(inputs), *args)
+    else:
+        return func(*inputs)
+
+
+class CheckpointFunction(torch.autograd.Function):
+    @staticmethod
+    def forward(ctx, run_function, length, *args):
+        ctx.run_function = run_function
+        ctx.input_tensors = list(args[:length])
+        ctx.input_params = list(args[length:])
+        ctx.gpu_autocast_kwargs = {
+            "enabled": torch.is_autocast_enabled(),
+            "dtype": torch.get_autocast_gpu_dtype(),
+            "cache_enabled": torch.is_autocast_cache_enabled(),
+        }
+        with torch.no_grad():
+            output_tensors = ctx.run_function(*ctx.input_tensors)
+        return output_tensors
+
+    @staticmethod
+    def backward(ctx, *output_grads):
+        ctx.input_tensors = [x.detach().requires_grad_(True) for x in ctx.input_tensors]
+        with torch.enable_grad(), torch.cuda.amp.autocast(**ctx.gpu_autocast_kwargs):
+            # Fixes a bug where the first op in run_function modifies the
+            # Tensor storage in place, which is not allowed for detach()'d
+            # Tensors.
+            shallow_copies = [x.view_as(x) for x in ctx.input_tensors]
+            output_tensors = ctx.run_function(*shallow_copies)
+        input_grads = torch.autograd.grad(
+            output_tensors,
+            ctx.input_tensors + ctx.input_params,
+            output_grads,
+            allow_unused=True,
+        )
+        del ctx.input_tensors
+        del ctx.input_params
+        del output_tensors
+        return (None, None) + input_grads
+
+
+def timestep_embedding(timesteps, dim, max_period=10000, repeat_only=False):
+    """
+    Create sinusoidal timestep embeddings.
+    :param timesteps: a 1-D Tensor of N indices, one per batch element.
+                      These may be fractional.
+    :param dim: the dimension of the output.
+    :param max_period: controls the minimum frequency of the embeddings.
+    :return: an [N x dim] Tensor of positional embeddings.
+    """
+    if not repeat_only:
+        half = dim // 2
+        freqs = torch.exp(
+            -math.log(max_period)
+            * torch.arange(start=0, end=half, dtype=torch.float32)
+            / half
+        ).to(device=timesteps.device)
+        args = timesteps[:, None].float() * freqs[None]
+        embedding = torch.cat([torch.cos(args), torch.sin(args)], dim=-1)
+        if dim % 2:
+            embedding = torch.cat(
+                [embedding, torch.zeros_like(embedding[:, :1])], dim=-1
+            )
+    else:
+        embedding = repeat(timesteps, "b -> b d", d=dim)
+    return embedding
+
+
+def zero_module(module):
+    """
+    Zero out the parameters of a module and return it.
+    """
+    for p in module.parameters():
+        p.detach().zero_()
+    return module
+
+
+def scale_module(module, scale):
+    """
+    Scale the parameters of a module and return it.
+    """
+    for p in module.parameters():
+        p.detach().mul_(scale)
+    return module
+
+
+def mean_flat(tensor):
+    """
+    Take the mean over all non-batch dimensions.
+    """
+    return tensor.mean(dim=list(range(1, len(tensor.shape))))
+
+
+def normalization(channels):
+    """
+    Make a standard normalization layer.
+    :param channels: number of input channels.
+    :return: an nn.Module for normalization.
+    """
+    return GroupNorm32(32, channels)
+
+
+# PyTorch 1.7 has SiLU, but we support PyTorch 1.5.
+class SiLU(nn.Module):
+    def forward(self, x):
+        return x * torch.sigmoid(x)
+
+
+class GroupNorm32(nn.GroupNorm):
+    def forward(self, x):
+        return super().forward(x.float()).type(x.dtype)
+
+
+def conv_nd(dims, *args, **kwargs):
+    """
+    Create a 1D, 2D, or 3D convolution module.
+    """
+    if dims == 1:
+        return nn.Conv1d(*args, **kwargs)
+    elif dims == 2:
+        return nn.Conv2d(*args, **kwargs)
+    elif dims == 3:
+        return nn.Conv3d(*args, **kwargs)
+    raise ValueError(f"unsupported dimensions: {dims}")
+
+
+def linear(*args, **kwargs):
+    """
+    Create a linear module.
+    """
+    return nn.Linear(*args, **kwargs)
+
+
+def avg_pool_nd(dims, *args, **kwargs):
+    """
+    Create a 1D, 2D, or 3D average pooling module.
+    """
+    if dims == 1:
+        return nn.AvgPool1d(*args, **kwargs)
+    elif dims == 2:
+        return nn.AvgPool2d(*args, **kwargs)
+    elif dims == 3:
+        return nn.AvgPool3d(*args, **kwargs)
+    raise ValueError(f"unsupported dimensions: {dims}")

sgm/modules/diffusionmodules/wrappers.py

@@ -0,0 +1,34 @@
+import torch
+import torch.nn as nn
+from packaging import version
+
+OPENAIUNETWRAPPER = "sgm.modules.diffusionmodules.wrappers.OpenAIWrapper"
+
+
+class IdentityWrapper(nn.Module):
+    def __init__(self, diffusion_model, compile_model: bool = False):
+        super().__init__()
+        compile = (
+            torch.compile
+            if (version.parse(torch.__version__) >= version.parse("2.0.0"))
+            and compile_model
+            else lambda x: x
+        )
+        self.diffusion_model = compile(diffusion_model)
+
+    def forward(self, *args, **kwargs):
+        return self.diffusion_model(*args, **kwargs)
+
+
+class OpenAIWrapper(IdentityWrapper):
+    def forward(
+        self, x: torch.Tensor, t: torch.Tensor, c: dict, **kwargs
+    ) -> torch.Tensor:
+        x = torch.cat((x, c.get("concat", torch.Tensor([]).type_as(x))), dim=1)
+        return self.diffusion_model(
+            x,
+            timesteps=t,
+            context=c.get("crossattn", None),
+            y=c.get("vector", None),
+            **kwargs
+        )