Add modular pipeline for HunyuanVideo 1.5

[akshan-main]

What does this PR do?

Adds modular pipeline blocks for HunyuanVideo 1.5 with both text-to-video (HunyuanVideo15Blocks) and image-to-video (HunyuanVideo15Image2VideoBlocks).

Parity verified on Colab G4 GPU:

• T2V: MAD 0.000000 vs HunyuanVideo15Pipeline

hv15_t2v_standard.mp4

hv15_t2v_modular.mp4

T2V reproduction code

import gc
import numpy as np
import torch
from diffusers import (
    HunyuanVideo15Pipeline,
    HunyuanVideo15ImageToVideoPipeline,
    HunyuanVideo15Blocks,
    HunyuanVideo15ModularPipeline,
)
from diffusers.utils import load_image, export_to_video

device = "cuda"
dtype = torch.bfloat16

T2V_ID = "hunyuanvideo-community/HunyuanVideo-1.5-Diffusers-480p_t2v"
I2V_ID = "hunyuanvideo-community/HunyuanVideo-1.5-Diffusers-480p_i2v"

def to_np(x):
    if hasattr(x, "frames"):
        x = x.frames
    if isinstance(x, list):
        x = np.array(x)
    if isinstance(x, torch.Tensor):
        x = x.float().cpu().numpy()
    return x
prompt = "A cinematic drone shot over snowy mountains at sunrise."

print("=== Standard T2V ===")

ref_pipe = HunyuanVideo15Pipeline.from_pretrained(T2V_ID, torch_dtype=dtype).to(device)
g = torch.Generator(device=device).manual_seed(1234)
ref_out = ref_pipe(prompt=prompt, num_frames=55, num_inference_steps=6, generator=g, output_type="np").frames
print(f"Shape: {np.array(ref_out).shape}")
export_to_video(ref_out[0], "/content/hv15_t2v_standard.mp4", fps=24)
del ref_pipe; gc.collect(); torch.cuda.empty_cache()



print("\n=== Modular T2V ===")
blocks = HunyuanVideo15Blocks()
pipe = blocks.init_pipeline(T2V_ID)
pipe.load_components(torch_dtype=dtype)
pipe.to(device)

print("Guider type:", type(pipe.guider).__name__)
print("Guider scale:", pipe.guider.guidance_scale)
print("Guider enabled:", pipe.guider._enabled)
print("Guider num_conditions:", pipe.guider.num_conditions)
g = torch.Generator(device=device).manual_seed(1234)
mod_out = pipe(prompt=prompt, num_frames=55, num_inference_steps=6, generator=g, output="videos", output_type="np")
print(f"Shape: {np.array(mod_out).shape}")
export_to_video(mod_out[0], "/content/hv15_t2v_modular.mp4", fps=24)

diff = np.abs(to_np(ref_out).astype(float) - to_np(mod_out).astype(float)).mean()
print(f"\nT2V MAD: {diff:.6f}")
del pipe, blocks; gc.collect(); torch.cuda.empty_cache()

• I2V: MAD 0.000000 vs HunyuanVideo15ImageToVideoPipeline

hv15_i2v_standard.mp4

hv15_i2v_modular.mp4

I2V reproduction code

from diffusers.modular_pipelines import HunyuanVideo15Blocks, HunyuanVideo15Image2VideoBlocks, HunyuanVideo15ModularPipeline

image = load_image("https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/diffusers/cat.png").convert("RGB")

print("=== Standard I2V ===")
ref_pipe = HunyuanVideo15ImageToVideoPipeline.from_pretrained(I2V_ID, torch_dtype=dtype).to(device)
g = torch.Generator(device=device).manual_seed(1234)
ref_out = ref_pipe(image=image, prompt="A cat turns its head", num_frames=55, num_inference_steps=6, generator=g, output_type="np").frames
print(f"Shape: {np.array(ref_out).shape}")
export_to_video(ref_out[0], "/content/hv15_i2v_standard.mp4", fps=24)
del ref_pipe; gc.collect(); torch.cuda.empty_cache()

print("\n=== Modular I2V ===")
blocks = HunyuanVideo15Image2VideoBlocks()
pipe = blocks.init_pipeline(I2V_ID)
pipe.load_components(torch_dtype=dtype)
pipe.to(device)
g = torch.Generator(device=device).manual_seed(1234)
mod_out = pipe(image=image, prompt="A cat turns its head", num_frames=55, num_inference_steps=6, generator=g, output="videos", output_type="np")
print(f"Shape: {np.array(mod_out).shape}")
export_to_video(mod_out[0], "/content/hv15_i2v_modular.mp4", fps=24)

diff = np.abs(to_np(ref_out).astype(float) - to_np(mod_out).astype(float)).mean()
print(f"\nI2V MAD: {diff:.6f}")
print("\n=== Done ===")

Addresses #13295 (HunyuanVideo 1.5 contribution)

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline?
• Did you read our philosophy doc (important for complex PRs)?
• Was this discussed/approved via a GitHub issue or the forum? Please add a link to it if that's the case. — Modular Diffusers 🧨 #13295
• Did you make sure to update the documentation with your changes? Here are the documentation guidelines, and here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

@sayakpaul @yiyixuxu @asomoza