v5 release with triple architecture support and prompt enhancer

ltx_video/models/transformers/embeddings.py

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+# Adapted from: https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/embeddings.py
+import math
+
+import numpy as np
+import torch
+from einops import rearrange
+from torch import nn
+
+
+def get_timestep_embedding(
+    timesteps: torch.Tensor,
+    embedding_dim: int,
+    flip_sin_to_cos: bool = False,
+    downscale_freq_shift: float = 1,
+    scale: float = 1,
+    max_period: int = 10000,
+):
+    """
+    This matches the implementation in Denoising Diffusion Probabilistic Models: Create sinusoidal timestep embeddings.
+
+    :param timesteps: a 1-D Tensor of N indices, one per batch element.
+                      These may be fractional.
+    :param embedding_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.
+    """
+    assert len(timesteps.shape) == 1, "Timesteps should be a 1d-array"
+
+    half_dim = embedding_dim // 2
+    exponent = -math.log(max_period) * torch.arange(
+        start=0, end=half_dim, dtype=torch.float32, device=timesteps.device
+    )
+    exponent = exponent / (half_dim - downscale_freq_shift)
+
+    emb = torch.exp(exponent)
+    emb = timesteps[:, None].float() * emb[None, :]
+
+    # scale embeddings
+    emb = scale * emb
+
+    # concat sine and cosine embeddings
+    emb = torch.cat([torch.sin(emb), torch.cos(emb)], dim=-1)
+
+    # flip sine and cosine embeddings
+    if flip_sin_to_cos:
+        emb = torch.cat([emb[:, half_dim:], emb[:, :half_dim]], dim=-1)
+
+    # zero pad
+    if embedding_dim % 2 == 1:
+        emb = torch.nn.functional.pad(emb, (0, 1, 0, 0))
+    return emb
+
+
+def get_3d_sincos_pos_embed(embed_dim, grid, w, h, f):
+    """
+    grid_size: int of the grid height and width return: pos_embed: [grid_size*grid_size, embed_dim] or
+    [1+grid_size*grid_size, embed_dim] (w/ or w/o cls_token)
+    """
+    grid = rearrange(grid, "c (f h w) -> c f h w", h=h, w=w)
+    grid = rearrange(grid, "c f h w -> c h w f", h=h, w=w)
+    grid = grid.reshape([3, 1, w, h, f])
+    pos_embed = get_3d_sincos_pos_embed_from_grid(embed_dim, grid)
+    pos_embed = pos_embed.transpose(1, 0, 2, 3)
+    return rearrange(pos_embed, "h w f c -> (f h w) c")
+
+
+def get_3d_sincos_pos_embed_from_grid(embed_dim, grid):
+    if embed_dim % 3 != 0:
+        raise ValueError("embed_dim must be divisible by 3")
+
+    # use half of dimensions to encode grid_h
+    emb_f = get_1d_sincos_pos_embed_from_grid(embed_dim // 3, grid[0])  # (H*W*T, D/3)
+    emb_h = get_1d_sincos_pos_embed_from_grid(embed_dim // 3, grid[1])  # (H*W*T, D/3)
+    emb_w = get_1d_sincos_pos_embed_from_grid(embed_dim // 3, grid[2])  # (H*W*T, D/3)
+
+    emb = np.concatenate([emb_h, emb_w, emb_f], axis=-1)  # (H*W*T, D)
+    return emb
+
+
+def get_1d_sincos_pos_embed_from_grid(embed_dim, pos):
+    """
+    embed_dim: output dimension for each position pos: a list of positions to be encoded: size (M,) out: (M, D)
+    """
+    if embed_dim % 2 != 0:
+        raise ValueError("embed_dim must be divisible by 2")
+
+    omega = np.arange(embed_dim // 2, dtype=np.float64)
+    omega /= embed_dim / 2.0
+    omega = 1.0 / 10000**omega  # (D/2,)
+
+    pos_shape = pos.shape
+
+    pos = pos.reshape(-1)
+    out = np.einsum("m,d->md", pos, omega)  # (M, D/2), outer product
+    out = out.reshape([*pos_shape, -1])[0]
+
+    emb_sin = np.sin(out)  # (M, D/2)
+    emb_cos = np.cos(out)  # (M, D/2)
+
+    emb = np.concatenate([emb_sin, emb_cos], axis=-1)  # (M, D)
+    return emb
+
+
+class SinusoidalPositionalEmbedding(nn.Module):
+    """Apply positional information to a sequence of embeddings.
+
+    Takes in a sequence of embeddings with shape (batch_size, seq_length, embed_dim) and adds positional embeddings to
+    them
+
+    Args:
+        embed_dim: (int): Dimension of the positional embedding.
+        max_seq_length: Maximum sequence length to apply positional embeddings
+
+    """
+
+    def __init__(self, embed_dim: int, max_seq_length: int = 32):
+        super().__init__()
+        position = torch.arange(max_seq_length).unsqueeze(1)
+        div_term = torch.exp(
+            torch.arange(0, embed_dim, 2) * (-math.log(10000.0) / embed_dim)
+        )
+        pe = torch.zeros(1, max_seq_length, embed_dim)
+        pe[0, :, 0::2] = torch.sin(position * div_term)
+        pe[0, :, 1::2] = torch.cos(position * div_term)
+        self.register_buffer("pe", pe)
+
+    def forward(self, x):
+        _, seq_length, _ = x.shape
+        x = x + self.pe[:, :seq_length]
+        return x