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hao-ai-lab-FastVideo/fastvideo-kernel/tests/support_flex_sta.py
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2025-12-26 01:50:24 -06:00

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Python

from typing import Tuple
import torch
from torch import BoolTensor, IntTensor
from torch.nn.attention.flex_attention import create_block_mask
# Peiyuan: This is neccesay. Dont know why. see https://github.com/pytorch/pytorch/issues/135028
torch._inductor.config.realize_opcount_threshold = 100
def generate_sta_mask(canvas_twh, kernel_twh, tile_twh, text_length):
"""Generates a 3D NATTEN attention mask with a given kernel size.
Args:
canvas_t: The time dimension of the canvas.
canvas_h: The height of the canvas.
canvas_w: The width of the canvas.
kernel_t: The time dimension of the kernel.
kernel_h: The height of the kernel.
kernel_w: The width of the kernel.
"""
canvas_t, canvas_h, canvas_w = canvas_twh
kernel_t, kernel_h, kernel_w = kernel_twh
tile_t_size, tile_h_size, tile_w_size = tile_twh
total_tile_size = tile_t_size * tile_h_size * tile_w_size
canvas_tile_t, canvas_tile_h, canvas_tile_w = canvas_t // tile_t_size, canvas_h // tile_h_size, canvas_w // tile_w_size
img_seq_len = canvas_t * canvas_h * canvas_w
def get_tile_t_x_y(idx: IntTensor) -> Tuple[IntTensor, IntTensor, IntTensor]:
tile_id = idx // total_tile_size
tile_t = tile_id // (canvas_tile_h * canvas_tile_w)
tile_h = (tile_id % (canvas_tile_h * canvas_tile_w)) // canvas_tile_w
tile_w = tile_id % canvas_tile_w
return tile_t, tile_h, tile_w
def sta_mask_3d(
b: IntTensor,
h: IntTensor,
q_idx: IntTensor,
kv_idx: IntTensor,
) -> BoolTensor:
q_t_tile, q_x_tile, q_y_tile = get_tile_t_x_y(q_idx)
kv_t_tile, kv_x_tile, kv_y_tile = get_tile_t_x_y(kv_idx)
# kernel nominally attempts to center itself on the query, but kernel center
# is clamped to a fixed distance (kernel half-length) from the canvas edge
kernel_center_t = q_t_tile.clamp(kernel_t // 2, (canvas_tile_t - 1) - kernel_t // 2)
kernel_center_x = q_x_tile.clamp(kernel_h // 2, (canvas_tile_h - 1) - kernel_h // 2)
kernel_center_y = q_y_tile.clamp(kernel_w // 2, (canvas_tile_w - 1) - kernel_w // 2)
time_mask = (kernel_center_t - kv_t_tile).abs() <= kernel_t // 2
hori_mask = (kernel_center_x - kv_x_tile).abs() <= kernel_h // 2
vert_mask = (kernel_center_y - kv_y_tile).abs() <= kernel_w // 2
image_mask = (q_idx < img_seq_len) & (kv_idx < img_seq_len)
image_to_text_mask = (q_idx < img_seq_len) & (kv_idx >= img_seq_len) & (kv_idx < img_seq_len + text_length)
text_to_all_mask = (q_idx >= img_seq_len) & (kv_idx < img_seq_len + text_length)
return (image_mask & time_mask & hori_mask & vert_mask) | image_to_text_mask | text_to_all_mask
sta_mask_3d.__name__ = f"natten_3d_c{canvas_t}x{canvas_w}x{canvas_h}_k{kernel_t}x{kernel_w}x{kernel_h}"
return sta_mask_3d
def get_sliding_tile_attention_mask(kernel_size, tile_size, img_size, text_length, device, text_max_len=256):
img_seq_len = img_size[0] * img_size[1] * img_size[2]
image_mask = generate_sta_mask(img_size, kernel_size, tile_size, text_length)
mask = create_block_mask(image_mask,
B=None,
H=None,
Q_LEN=img_seq_len + text_max_len,
KV_LEN=img_seq_len + text_max_len,
device=device,
_compile=True)
return mask