model_v2w.py

# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from dataclasses import dataclass
from typing import Callable, Dict, Optional, Tuple, Union

import torch
from torch import Tensor

from cosmos1.models.diffusion.conditioner import VideoExtendCondition
from cosmos1.models.diffusion.config.base.conditioner import VideoCondBoolConfig
from cosmos1.models.diffusion.diffusion.functional.batch_ops import batch_mul
from cosmos1.models.diffusion.model.model_t2w import DiffusionT2WModel
from cosmos1.utils import log, misc


@dataclass
class VideoDenoisePrediction:
    x0: torch.Tensor  # clean data prediction
    eps: Optional[torch.Tensor] = None  # noise prediction
    logvar: Optional[torch.Tensor] = None  # log variance of noise prediction, can be used a confidence / uncertainty
    xt: Optional[torch.Tensor] = None  # input to the network, before muliply with c_in
    x0_pred_replaced: Optional[torch.Tensor] = None  # x0 prediction with condition region replaced by gt_latent


class DiffusionV2WModel(DiffusionT2WModel):
    def __init__(self, config):
        super().__init__(config)

    def augment_conditional_latent_frames(
        self,
        condition: VideoExtendCondition,
        cfg_video_cond_bool: VideoCondBoolConfig,
        gt_latent: Tensor,
        condition_video_augment_sigma_in_inference: float = 0.001,
        sigma: Tensor = None,
        seed: int = 1,
    ) -> Union[VideoExtendCondition, Tensor]:
        """Augments the conditional frames with noise during inference.

        Args:
            condition (VideoExtendCondition): condition object
                condition_video_indicator: binary tensor indicating the region is condition(value=1) or generation(value=0). Bx1xTx1x1 tensor.
                condition_video_input_mask: input mask for the network input, indicating the condition region. B,1,T,H,W tensor. will be concat with the input for the network.
            cfg_video_cond_bool (VideoCondBoolConfig): video condition bool config
            gt_latent (Tensor): ground truth latent tensor in shape B,C,T,H,W
            condition_video_augment_sigma_in_inference (float): sigma for condition video augmentation in inference
            sigma (Tensor): noise level for the generation region
            seed (int): random seed for reproducibility
        Returns:
            VideoExtendCondition: updated condition object
                condition_video_augment_sigma: sigma for the condition region, feed to the network
            augment_latent (Tensor): augmented latent tensor in shape B,C,T,H,W

        """

        # Inference only, use fixed sigma for the condition region
        assert (
            condition_video_augment_sigma_in_inference is not None
        ), "condition_video_augment_sigma_in_inference should be provided"
        augment_sigma = condition_video_augment_sigma_in_inference

        if augment_sigma >= sigma.flatten()[0]:
            # This is a inference trick! If the sampling sigma is smaller than the augment sigma, we will start denoising the condition region together.
            # This is achieved by setting all region as `generation`, i.e. value=0
            log.debug("augment_sigma larger than sigma or other frame, remove condition")
            condition.condition_video_indicator = condition.condition_video_indicator * 0

        augment_sigma = torch.tensor([augment_sigma], **self.tensor_kwargs)

        # Now apply the augment_sigma to the gt_latent

        noise = misc.arch_invariant_rand(
            gt_latent.shape,
            torch.float32,
            self.tensor_kwargs["device"],
            seed,
        )

        augment_latent = gt_latent + noise * augment_sigma[:, None, None, None, None]

        _, _, c_in_augment, _ = self.scaling(sigma=augment_sigma)

        # Multiply the whole latent with c_in_augment
        augment_latent_cin = batch_mul(augment_latent, c_in_augment)

        # Since the whole latent will multiply with c_in later, we devide the value to cancel the effect
        _, _, c_in, _ = self.scaling(sigma=sigma)
        augment_latent_cin = batch_mul(augment_latent_cin, 1 / c_in)

        return condition, augment_latent_cin

    def denoise(
        self,
        noise_x: Tensor,
        sigma: Tensor,
        condition: VideoExtendCondition,
        condition_video_augment_sigma_in_inference: float = 0.001,
        seed: int = 1,
    ) -> VideoDenoisePrediction:
        """Denoises input tensor using conditional video generation.

        Args:
            noise_x (Tensor): Noisy input tensor.
            sigma (Tensor): Noise level.
            condition (VideoExtendCondition): Condition for denoising.
            condition_video_augment_sigma_in_inference (float): sigma for condition video augmentation in inference
            seed (int): Random seed for reproducibility
        Returns:
            VideoDenoisePrediction containing:
            - x0: Denoised prediction
            - eps: Noise prediction
            - logvar: Log variance of noise prediction
            - xt: Input before c_in multiplication
            - x0_pred_replaced: x0 prediction with condition regions replaced by ground truth
        """

        assert (
            condition.gt_latent is not None
        ), f"find None gt_latent in condition, likely didn't call self.add_condition_video_indicator_and_video_input_mask when preparing the condition or this is a image batch but condition.data_type is wrong, get {noise_x.shape}"
        gt_latent = condition.gt_latent
        cfg_video_cond_bool: VideoCondBoolConfig = self.config.conditioner.video_cond_bool

        condition_latent = gt_latent

        # Augment the latent with different sigma value, and add the augment_sigma to the condition object if needed
        condition, augment_latent = self.augment_conditional_latent_frames(
            condition, cfg_video_cond_bool, condition_latent, condition_video_augment_sigma_in_inference, sigma, seed
        )
        condition_video_indicator = condition.condition_video_indicator  # [B, 1, T, 1, 1]

        # Compose the model input with condition region (augment_latent) and generation region (noise_x)
        new_noise_xt = condition_video_indicator * augment_latent + (1 - condition_video_indicator) * noise_x
        # Call the abse model
        denoise_pred = super().denoise(new_noise_xt, sigma, condition)

        x0_pred_replaced = condition_video_indicator * gt_latent + (1 - condition_video_indicator) * denoise_pred.x0

        x0_pred = x0_pred_replaced

        return VideoDenoisePrediction(
            x0=x0_pred,
            eps=batch_mul(noise_x - x0_pred, 1.0 / sigma),
            logvar=denoise_pred.logvar,
            xt=new_noise_xt,
            x0_pred_replaced=x0_pred_replaced,
        )

    def generate_samples_from_batch(
        self,
        data_batch: Dict,
        guidance: float = 1.5,
        seed: int = 1,
        state_shape: Tuple | None = None,
        n_sample: int | None = None,
        is_negative_prompt: bool = False,
        num_steps: int = 35,
        condition_latent: Union[torch.Tensor, None] = None,
        num_condition_t: Union[int, None] = None,
        condition_video_augment_sigma_in_inference: float = None,
        add_input_frames_guidance: bool = False,
        x_sigma_max: Optional[torch.Tensor] = None,
    ) -> Tensor:
        """Generates video samples conditioned on input frames.

        Args:
            data_batch: Input data dictionary
            guidance: Classifier-free guidance scale
            seed: Random seed for reproducibility
            state_shape: Shape of output tensor (defaults to model's state shape)
            n_sample: Number of samples to generate (defaults to batch size)
            is_negative_prompt: Whether to use negative prompting
            num_steps: Number of denoising steps
            condition_latent: Conditioning frames tensor (B,C,T,H,W)
            num_condition_t: Number of frames to condition on
            condition_video_augment_sigma_in_inference: Noise level for condition augmentation
            add_input_frames_guidance: Whether to apply guidance to input frames
            x_sigma_max: Maximum noise level tensor

        Returns:
            Generated video samples tensor
        """

        if n_sample is None:
            input_key = self.input_data_key
            n_sample = data_batch[input_key].shape[0]
        if state_shape is None:
            log.debug(f"Default Video state shape is used. {self.state_shape}")
            state_shape = self.state_shape

        assert condition_latent is not None, "condition_latent should be provided"

        x0_fn = self.get_x0_fn_from_batch_with_condition_latent(
            data_batch,
            guidance,
            is_negative_prompt=is_negative_prompt,
            condition_latent=condition_latent,
            num_condition_t=num_condition_t,
            condition_video_augment_sigma_in_inference=condition_video_augment_sigma_in_inference,
            add_input_frames_guidance=add_input_frames_guidance,
            seed=seed,
        )
        if x_sigma_max is None:
            x_sigma_max = (
                misc.arch_invariant_rand(
                    (n_sample,) + tuple(state_shape),
                    torch.float32,
                    self.tensor_kwargs["device"],
                    seed,
                )
                * self.sde.sigma_max
            )

        samples = self.sampler(x0_fn, x_sigma_max, num_steps=num_steps, sigma_max=self.sde.sigma_max)
        return samples

    def get_x0_fn_from_batch_with_condition_latent(
        self,
        data_batch: Dict,
        guidance: float = 1.5,
        is_negative_prompt: bool = False,
        condition_latent: torch.Tensor = None,
        num_condition_t: Union[int, None] = None,
        condition_video_augment_sigma_in_inference: float = None,
        add_input_frames_guidance: bool = False,
        seed: int = 1,
    ) -> Callable:
        """Creates denoising function for conditional video generation.

        Args:
            data_batch: Input data dictionary
            guidance: Classifier-free guidance scale
            is_negative_prompt: Whether to use negative prompting
            condition_latent: Conditioning frames tensor (B,C,T,H,W)
            num_condition_t: Number of frames to condition on
            condition_video_augment_sigma_in_inference: Noise level for condition augmentation
            add_input_frames_guidance: Whether to apply guidance to input frames
            seed: Random seed for reproducibility

        Returns:
            Function that takes noisy input and noise level and returns denoised prediction
        """
        if is_negative_prompt:
            condition, uncondition = self.conditioner.get_condition_with_negative_prompt(data_batch)
        else:
            condition, uncondition = self.conditioner.get_condition_uncondition(data_batch)

        condition.video_cond_bool = True
        condition = self.add_condition_video_indicator_and_video_input_mask(
            condition_latent, condition, num_condition_t
        )

        uncondition.video_cond_bool = False if add_input_frames_guidance else True
        uncondition = self.add_condition_video_indicator_and_video_input_mask(
            condition_latent, uncondition, num_condition_t
        )

        def x0_fn(noise_x: torch.Tensor, sigma: torch.Tensor) -> torch.Tensor:
            cond_x0 = self.denoise(
                noise_x,
                sigma,
                condition,
                condition_video_augment_sigma_in_inference=condition_video_augment_sigma_in_inference,
                seed=seed,
            ).x0_pred_replaced
            uncond_x0 = self.denoise(
                noise_x,
                sigma,
                uncondition,
                condition_video_augment_sigma_in_inference=condition_video_augment_sigma_in_inference,
                seed=seed,
            ).x0_pred_replaced

            return cond_x0 + guidance * (cond_x0 - uncond_x0)

        return x0_fn

    def add_condition_video_indicator_and_video_input_mask(
        self, latent_state: torch.Tensor, condition: VideoExtendCondition, num_condition_t: Union[int, None] = None
    ) -> VideoExtendCondition:
        """Adds conditioning masks to VideoExtendCondition object.

        Creates binary indicators and input masks for conditional video generation.

        Args:
            latent_state: Input latent tensor (B,C,T,H,W)
            condition: VideoExtendCondition object to update
            num_condition_t: Number of frames to condition on

        Returns:
            Updated VideoExtendCondition with added masks:
            - condition_video_indicator: Binary tensor marking condition regions
            - condition_video_input_mask: Input mask for network
            - gt_latent: Ground truth latent tensor
        """
        T = latent_state.shape[2]
        latent_dtype = latent_state.dtype
        condition_video_indicator = torch.zeros(1, 1, T, 1, 1, device=latent_state.device).type(
            latent_dtype
        )  # 1 for condition region

        # Only in inference to decide the condition region
        assert num_condition_t is not None, "num_condition_t should be provided"
        assert num_condition_t <= T, f"num_condition_t should be less than T, get {num_condition_t}, {T}"
        log.debug(
            f"condition_location first_n, num_condition_t {num_condition_t}, condition.video_cond_bool {condition.video_cond_bool}"
        )
        condition_video_indicator[:, :, :num_condition_t] += 1.0

        condition.gt_latent = latent_state
        condition.condition_video_indicator = condition_video_indicator

        B, C, T, H, W = latent_state.shape
        # Create additional input_mask channel, this will be concatenated to the input of the network
        # See design doc section (Implementation detail A.1 and A.2) for visualization
        ones_padding = torch.ones((B, 1, T, H, W), dtype=latent_state.dtype, device=latent_state.device)
        zeros_padding = torch.zeros((B, 1, T, H, W), dtype=latent_state.dtype, device=latent_state.device)
        assert condition.video_cond_bool is not None, "video_cond_bool should be set"

        # The input mask indicate whether the input is conditional region or not
        if condition.video_cond_bool:  # Condition one given video frames
            condition.condition_video_input_mask = (
                condition_video_indicator * ones_padding + (1 - condition_video_indicator) * zeros_padding
            )
        else:  # Unconditional case, use for cfg
            condition.condition_video_input_mask = zeros_padding

        return condition