ldm_patched/modules/model_sampling.py

# 1st edit by https://github.com/comfyanonymous/ComfyUI
# 2nd edit by Forge Official


import math

import numpy as np
import torch
from ldm_patched.ldm.modules.diffusionmodules.util import make_beta_schedule


class EPS:
    def calculate_input(self, sigma, noise):
        sigma = sigma.view(sigma.shape[:1] + (1,) * (noise.ndim - 1))
        return noise / (sigma**2 + self.sigma_data**2) ** 0.5

    def calculate_denoised(self, sigma, model_output, model_input):
        sigma = sigma.view(sigma.shape[:1] + (1,) * (model_output.ndim - 1))
        return model_input - model_output * sigma


class V_PREDICTION(EPS):
    def calculate_denoised(self, sigma, model_output, model_input):
        sigma = sigma.view(sigma.shape[:1] + (1,) * (model_output.ndim - 1))
        return (
            model_input * self.sigma_data**2 / (sigma**2 + self.sigma_data**2)
            - model_output
            * sigma
            * self.sigma_data
            / (sigma**2 + self.sigma_data**2) ** 0.5
        )


class ModelSamplingDiscrete(torch.nn.Module):
    def __init__(self, model_config=None):
        super().__init__()

        if model_config is not None:
            sampling_settings = model_config.sampling_settings
        else:
            sampling_settings = {}

        beta_schedule = sampling_settings.get("beta_schedule", "linear")
        linear_start = sampling_settings.get("linear_start", 0.00085)
        linear_end = sampling_settings.get("linear_end", 0.012)

        self._register_schedule(
            given_betas=None,
            beta_schedule=beta_schedule,
            timesteps=1000,
            linear_start=linear_start,
            linear_end=linear_end,
            cosine_s=8e-3,
        )
        self.sigma_data = 1.0

    def _register_schedule(
        self,
        given_betas=None,
        beta_schedule="linear",
        timesteps=1000,
        linear_start=1e-4,
        linear_end=2e-2,
        cosine_s=8e-3,
    ):
        if given_betas is not None:
            betas = given_betas
        else:
            betas = make_beta_schedule(
                beta_schedule,
                timesteps,
                linear_start=linear_start,
                linear_end=linear_end,
                cosine_s=cosine_s,
            )
        alphas = 1.0 - betas
        alphas_cumprod = torch.tensor(np.cumprod(alphas, axis=0), dtype=torch.float32)
        # alphas_cumprod_prev = np.append(1., alphas_cumprod[:-1])

        (timesteps,) = betas.shape
        self.num_timesteps = int(timesteps)
        self.linear_start = linear_start
        self.linear_end = linear_end

        # self.register_buffer('betas', torch.tensor(betas, dtype=torch.float32))
        # self.register_buffer('alphas_cumprod', torch.tensor(alphas_cumprod, dtype=torch.float32))
        # self.register_buffer('alphas_cumprod_prev', torch.tensor(alphas_cumprod_prev, dtype=torch.float32))

        sigmas = ((1 - alphas_cumprod) / alphas_cumprod) ** 0.5
        self.set_sigmas(sigmas)

    def set_sigmas(self, sigmas):
        self.register_buffer("sigmas", sigmas)
        self.register_buffer("log_sigmas", sigmas.log())

    @property
    def sigma_min(self):
        return self.sigmas[0]

    @property
    def sigma_max(self):
        return self.sigmas[-1]

    def timestep(self, sigma):
        log_sigma = sigma.log()
        dists = log_sigma.to(self.log_sigmas.device) - self.log_sigmas[:, None]
        return dists.abs().argmin(dim=0).view(sigma.shape).to(sigma.device)

    def sigma(self, timestep):
        t = torch.clamp(
            timestep.float().to(self.log_sigmas.device),
            min=0,
            max=(len(self.sigmas) - 1),
        )
        low_idx = t.floor().long()
        high_idx = t.ceil().long()
        w = t.frac()
        log_sigma = (1 - w) * self.log_sigmas[low_idx] + w * self.log_sigmas[high_idx]
        return log_sigma.exp().to(timestep.device)

    def percent_to_sigma(self, percent):
        if percent <= 0.0:
            return 999999999.9
        if percent >= 1.0:
            return 0.0
        percent = 1.0 - percent
        return self.sigma(torch.tensor(percent * 999.0)).item()


class ModelSamplingContinuousEDM(torch.nn.Module):
    def __init__(self, model_config=None):
        super().__init__()
        self.sigma_data = 1.0

        if model_config is not None:
            sampling_settings = model_config.sampling_settings
        else:
            sampling_settings = {}

        sigma_min = sampling_settings.get("sigma_min", 0.002)
        sigma_max = sampling_settings.get("sigma_max", 120.0)
        self.set_sigma_range(sigma_min, sigma_max)

    def set_sigma_range(self, sigma_min, sigma_max):
        sigmas = torch.linspace(math.log(sigma_min), math.log(sigma_max), 1000).exp()

        self.register_buffer("sigmas", sigmas)  # for compatibility with some schedulers
        self.register_buffer("log_sigmas", sigmas.log())

    @property
    def sigma_min(self):
        return self.sigmas[0]

    @property
    def sigma_max(self):
        return self.sigmas[-1]

    def timestep(self, sigma):
        return 0.25 * sigma.log()

    def sigma(self, timestep):
        return (timestep / 0.25).exp()

    def percent_to_sigma(self, percent):
        if percent <= 0.0:
            return 999999999.9
        if percent >= 1.0:
            return 0.0
        percent = 1.0 - percent

        log_sigma_min = math.log(self.sigma_min)
        return math.exp(
            (math.log(self.sigma_max) - log_sigma_min) * percent + log_sigma_min
        )