SkyReelsV2Transformer3DModel

A Diffusion Transformer model for 3D video-like data was introduced in SkyReels-V2 by the Skywork AI.

The model can be loaded with the following code snippet.

from mindone.diffusers import SkyReelsV2Transformer3DModel

transformer = SkyReelsV2Transformer3DModel.from_pretrained("Skywork/SkyReels-V2-DF-1.3B-540P-Diffusers", subfolder="transformer", mindspore_dtype=ms.bfloat16)

mindone.diffusers.SkyReelsV2Transformer3DModel

Bases: ModelMixin, ConfigMixin, PeftAdapterMixin, FromOriginalModelMixin

A Transformer model for video-like data used in the Wan-based SkyReels-V2 model.

PARAMETER	DESCRIPTION
patch_size	3D patch dimensions for video embedding (t_patch, h_patch, w_patch). TYPE: `Tuple[int]`, defaults to `(1, 2, 2)` DEFAULT: (1, 2, 2)
num_attention_heads	Fixed length for text embeddings. TYPE: `int`, defaults to `16` DEFAULT: 16
attention_head_dim	The number of channels in each head. TYPE: `int`, defaults to `128` DEFAULT: 128
in_channels	The number of channels in the input. TYPE: `int`, defaults to `16` DEFAULT: 16
out_channels	The number of channels in the output. TYPE: `int`, defaults to `16` DEFAULT: 16
text_dim	Input dimension for text embeddings. TYPE: `int`, defaults to `4096` DEFAULT: 4096
freq_dim	Dimension for sinusoidal time embeddings. TYPE: `int`, defaults to `256` DEFAULT: 256
ffn_dim	Intermediate dimension in feed-forward network. TYPE: `int`, defaults to `8192` DEFAULT: 8192
num_layers	The number of layers of transformer blocks to use. TYPE: `int`, defaults to `32` DEFAULT: 32
window_size	Window size for local attention (-1 indicates global attention). TYPE: `Tuple[int]`, defaults to `(-1, -1)`
cross_attn_norm	Enable cross-attention normalization. TYPE: `bool`, defaults to `True` DEFAULT: True
qk_norm	Enable query/key normalization. TYPE: `str`, *optional*, defaults to `"rms_norm_across_heads"` DEFAULT: 'rms_norm_across_heads'
eps	Epsilon value for normalization layers. TYPE: `float`, defaults to `1e-6` DEFAULT: 1e-06
inject_sample_info	Whether to inject sample information into the model. TYPE: `bool`, defaults to `False` DEFAULT: False
image_dim	The dimension of the image embeddings. TYPE: `int`, *optional* DEFAULT: None
added_kv_proj_dim	The dimension of the added key/value projection. TYPE: `int`, *optional* DEFAULT: None
rope_max_seq_len	The maximum sequence length for the rotary embeddings. TYPE: `int`, defaults to `1024` DEFAULT: 1024
pos_embed_seq_len	The sequence length for the positional embeddings. TYPE: `int`, *optional* DEFAULT: None

Source code in mindone/diffusers/models/transformers/transformer_skyreels_v2.py

class SkyReelsV2Transformer3DModel(ModelMixin, ConfigMixin, PeftAdapterMixin, FromOriginalModelMixin):
    r"""
    A Transformer model for video-like data used in the Wan-based SkyReels-V2 model.

    Args:
        patch_size (`Tuple[int]`, defaults to `(1, 2, 2)`):
            3D patch dimensions for video embedding (t_patch, h_patch, w_patch).
        num_attention_heads (`int`, defaults to `16`):
            Fixed length for text embeddings.
        attention_head_dim (`int`, defaults to `128`):
            The number of channels in each head.
        in_channels (`int`, defaults to `16`):
            The number of channels in the input.
        out_channels (`int`, defaults to `16`):
            The number of channels in the output.
        text_dim (`int`, defaults to `4096`):
            Input dimension for text embeddings.
        freq_dim (`int`, defaults to `256`):
            Dimension for sinusoidal time embeddings.
        ffn_dim (`int`, defaults to `8192`):
            Intermediate dimension in feed-forward network.
        num_layers (`int`, defaults to `32`):
            The number of layers of transformer blocks to use.
        window_size (`Tuple[int]`, defaults to `(-1, -1)`):
            Window size for local attention (-1 indicates global attention).
        cross_attn_norm (`bool`, defaults to `True`):
            Enable cross-attention normalization.
        qk_norm (`str`, *optional*, defaults to `"rms_norm_across_heads"`):
            Enable query/key normalization.
        eps (`float`, defaults to `1e-6`):
            Epsilon value for normalization layers.
        inject_sample_info (`bool`, defaults to `False`):
            Whether to inject sample information into the model.
        image_dim (`int`, *optional*):
            The dimension of the image embeddings.
        added_kv_proj_dim (`int`, *optional*):
            The dimension of the added key/value projection.
        rope_max_seq_len (`int`, defaults to `1024`):
            The maximum sequence length for the rotary embeddings.
        pos_embed_seq_len (`int`, *optional*):
            The sequence length for the positional embeddings.
    """

    _supports_gradient_checkpointing = True
    _skip_layerwise_casting_patterns = ["patch_embedding", "condition_embedder", "norm"]
    _no_split_modules = ["SkyReelsV2TransformerBlock"]
    _keep_in_fp32_modules = ["time_embedder", "scale_shift_table", "norm1", "norm2", "norm3"]
    _keys_to_ignore_on_load_unexpected = ["norm_added_q"]

    @register_to_config
    def __init__(
        self,
        patch_size: Tuple[int] = (1, 2, 2),
        num_attention_heads: int = 16,
        attention_head_dim: int = 128,
        in_channels: int = 16,
        out_channels: int = 16,
        text_dim: int = 4096,
        freq_dim: int = 256,
        ffn_dim: int = 8192,
        num_layers: int = 32,
        cross_attn_norm: bool = True,
        qk_norm: Optional[str] = "rms_norm_across_heads",
        eps: float = 1e-6,
        image_dim: Optional[int] = None,
        added_kv_proj_dim: Optional[int] = None,
        rope_max_seq_len: int = 1024,
        pos_embed_seq_len: Optional[int] = None,
        inject_sample_info: bool = False,
        num_frame_per_block: int = 1,
    ) -> None:
        super().__init__()

        inner_dim = num_attention_heads * attention_head_dim
        out_channels = out_channels or in_channels

        # 1. Patch & position embedding
        self.rope = SkyReelsV2RotaryPosEmbed(attention_head_dim, patch_size, rope_max_seq_len)
        self.patch_embedding = mint.nn.Conv3d(
            in_channels, inner_dim, kernel_size=tuple(patch_size), stride=tuple(patch_size)
        )

        # 2. Condition embeddings
        # image_embedding_dim=1280 for I2V model
        self.condition_embedder = SkyReelsV2TimeTextImageEmbedding(
            dim=inner_dim,
            time_freq_dim=freq_dim,
            time_proj_dim=inner_dim * 6,
            text_embed_dim=text_dim,
            image_embed_dim=image_dim,
            pos_embed_seq_len=pos_embed_seq_len,
        )

        # 3. Transformer blocks
        self.blocks = nn.CellList(
            [
                SkyReelsV2TransformerBlock(
                    inner_dim, ffn_dim, num_attention_heads, qk_norm, cross_attn_norm, eps, added_kv_proj_dim
                )
                for _ in range(num_layers)
            ]
        )

        # 4. Output norm & projection
        self.norm_out = FP32LayerNorm(inner_dim, eps, elementwise_affine=False)
        self.proj_out = mint.nn.Linear(inner_dim, out_channels * math.prod(patch_size))
        self.scale_shift_table = ms.Parameter(mint.randn(1, 2, inner_dim) / inner_dim**0.5, name="scale_shift_table")

        if inject_sample_info:
            self.fps_embedding = mint.nn.Embedding(2, inner_dim)
            self.fps_projection = FeedForward(inner_dim, inner_dim * 6, mult=1, activation_fn="linear-silu")

        self.gradient_checkpointing = False

    def construct(
        self,
        hidden_states: ms.Tensor,
        timestep: ms.Tensor,
        encoder_hidden_states: ms.Tensor,
        encoder_hidden_states_image: Optional[ms.Tensor] = None,
        enable_diffusion_forcing: bool = False,
        fps: Optional[ms.Tensor] = None,
        return_dict: bool = False,
        attention_kwargs: Optional[Dict[str, Any]] = None,
    ) -> Union[ms.Tensor, Dict[str, ms.Tensor]]:
        if attention_kwargs is not None:
            attention_kwargs = attention_kwargs.copy()

        if attention_kwargs is not None and attention_kwargs.get("scale", None) is not None:
            logger.warning("Passing `scale` via `attention_kwargs` when not using the PEFT backend is ineffective.")

        batch_size, num_channels, num_frames, height, width = hidden_states.shape
        p_t, p_h, p_w = self.config["patch_size"]
        post_patch_num_frames = num_frames // p_t
        post_patch_height = height // p_h
        post_patch_width = width // p_w

        rotary_emb = self.rope(hidden_states)

        hidden_states = self.patch_embedding(hidden_states)
        hidden_states = hidden_states.flatten(2).swapaxes(1, 2)

        causal_mask = None
        if self.config["num_frame_per_block"] > 1:
            block_num = post_patch_num_frames // self.config["num_frame_per_block"]
            range_tensor = mint.arange(block_num).repeat_interleave(self.config["num_frame_per_block"])
            causal_mask = range_tensor.unsqueeze(0) <= range_tensor.unsqueeze(1)  # f, f
            causal_mask = causal_mask.view(post_patch_num_frames, 1, 1, post_patch_num_frames, 1, 1)
            causal_mask = causal_mask.tile(
                (1, post_patch_height, post_patch_width, 1, post_patch_height, post_patch_width)
            )
            causal_mask = causal_mask.reshape(
                post_patch_num_frames * post_patch_height * post_patch_width,
                post_patch_num_frames * post_patch_height * post_patch_width,
            )
            causal_mask = causal_mask.unsqueeze(0).unsqueeze(0)

        temb, timestep_proj, encoder_hidden_states, encoder_hidden_states_image = self.condition_embedder(
            timestep, encoder_hidden_states, encoder_hidden_states_image
        )

        timestep_proj = unflatten(timestep_proj, -1, (6, -1))

        if encoder_hidden_states_image is not None:
            encoder_hidden_states = mint.concat([encoder_hidden_states_image, encoder_hidden_states], dim=1)

        if self.config["inject_sample_info"]:
            fps = ms.tensor(fps, dtype=ms.int64)

            fps_emb = self.fps_embedding(fps)
            if enable_diffusion_forcing:
                timestep_proj = timestep_proj + unflatten(self.fps_projection(fps_emb), 1, (6, -1)).tile(
                    (timestep.shape[1], 1, 1)
                )
            else:
                timestep_proj = timestep_proj + unflatten(self.fps_projection(fps_emb), 1, (6, -1))

        if enable_diffusion_forcing:
            b, f = timestep.shape
            temb = temb.view(b, f, 1, 1, -1)
            timestep_proj = timestep_proj.view(b, f, 1, 1, 6, -1)  # (b, f, 1, 1, 6, inner_dim)
            temb = temb.tile((1, 1, post_patch_height, post_patch_width, 1)).flatten(1, 3)
            timestep_proj = timestep_proj.tile((1, 1, post_patch_height, post_patch_width, 1, 1)).flatten(
                1, 3
            )  # (b, f, pp_h, pp_w, 6, inner_dim) -> (b, f * pp_h * pp_w, 6, inner_dim)
            timestep_proj = timestep_proj.swapaxes(1, 2).contiguous()  # (b, 6, f * pp_h * pp_w, inner_dim)

        # 4. Transformer blocks
        for block in self.blocks:
            hidden_states = block(
                hidden_states,
                encoder_hidden_states,
                timestep_proj,
                rotary_emb,
                causal_mask,
            )

        shift, scale = None, None
        if temb.dim() == 2:
            # If temb is 2D, we assume it has time 1-D time embedding values for each batch.
            # For models:
            # - Skywork/SkyReels-V2-T2V-14B-540P-Diffusers
            # - Skywork/SkyReels-V2-T2V-14B-720P-Diffusers
            # - Skywork/SkyReels-V2-I2V-1.3B-540P-Diffusers
            # - Skywork/SkyReels-V2-I2V-14B-540P-Diffusers
            # - Skywork/SkyReels-V2-I2V-14B-720P-Diffusers
            shift, scale = (self.scale_shift_table + temb.unsqueeze(1)).chunk(2, dim=1)
        elif temb.dim() == 3:
            # If temb is 3D, we assume it has 2-D time embedding values for each batch.
            # Each time embedding tensor includes values for each latent frame; thus Diffusion Forcing.
            # For models:
            # - Skywork/SkyReels-V2-DF-1.3B-540P-Diffusers
            # - Skywork/SkyReels-V2-DF-14B-540P-Diffusers
            # - Skywork/SkyReels-V2-DF-14B-720P-Diffusers
            shift, scale = (self.scale_shift_table.unsqueeze(2) + temb.unsqueeze(1)).chunk(2, dim=1)
            shift, scale = shift.squeeze(1), scale.squeeze(1)

        hidden_states = (self.norm_out(hidden_states.float()) * (1 + scale) + shift).type_as(hidden_states)

        hidden_states = self.proj_out(hidden_states)

        hidden_states = hidden_states.reshape(
            batch_size, post_patch_num_frames, post_patch_height, post_patch_width, p_t, p_h, p_w, -1
        )
        hidden_states = hidden_states.permute(0, 7, 1, 4, 2, 5, 3, 6)
        output = hidden_states.flatten(6, 7).flatten(4, 5).flatten(2, 3)

        if not return_dict:
            return (output,)

        return Transformer2DModelOutput(sample=output)

    def _set_ar_attention(self, causal_block_size: int):
        self.register_to_config(num_frame_per_block=causal_block_size)

mindone.diffusers.models.modeling_outputs.Transformer2DModelOutput dataclass

Bases: BaseOutput

The output of [Transformer2DModel].

PARAMETER	DESCRIPTION
`(batch	The hidden states output conditioned on the encoder_hidden_states input. If discrete, returns probability distributions for the unnoised latent pixels. TYPE: size, num_vector_embeds - 1, num_latent_pixels)` if [`Transformer2DModel`] is discrete

Source code in mindone/diffusers/models/modeling_outputs.py

@dataclass
class Transformer2DModelOutput(BaseOutput):
    """
    The output of [`Transformer2DModel`].

    Args:
        sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` or
        `(batch size, num_vector_embeds - 1, num_latent_pixels)` if [`Transformer2DModel`] is discrete):
            The hidden states output conditioned on the `encoder_hidden_states` input. If discrete, returns probability
            distributions for the unnoised latent pixels.
    """

    sample: "ms.Tensor"  # noqa: F821