app.py

import gradio as gr
import torch
import numpy as np
import torchvision.transforms.functional as TF
from diffusers import AutoencoderKLWan, WanImageToVideoPipeline
from diffusers.utils import export_to_video, load_image
from transformers import CLIPVisionModel

def generate_video(first_frame_url, last_frame_url, prompt):
    model_id = "Wan-AI/Wan2.1-FLF2V-14B-720P-diffusers"
    image_encoder = CLIPVisionModel.from_pretrained(model_id, subfolder="image_encoder", torch_dtype=torch.float32)
    vae = AutoencoderKLWan.from_pretrained(model_id, subfolder="vae", torch_dtype=torch.float32)
    pipe = WanImageToVideoPipeline.from_pretrained(low_cpu_mem_usage=True, model_id, vae=vae, image_encoder=image_encoder, torch_dtype=torch.bfloat16)
    pipe.to("cuda")

    first_frame = load_image(first_frame_url)
    last_frame = load_image(last_frame_url)

    def aspect_ratio_resize(image, pipe, max_area=720 * 1280):
        aspect_ratio = image.height / image.width
        mod_value = pipe.vae_scale_factor_spatial * pipe.transformer.config.patch_size[1]
        height = round(np.sqrt(max_area * aspect_ratio)) // mod_value * mod_value
        width = round(np.sqrt(max_area / aspect_ratio)) // mod_value * mod_value
        image = image.resize((width, height))
        return image, height, width

    def center_crop_resize(image, height, width):
        resize_ratio = max(width / image.width, height / image.height)
        width = round(image.width * resize_ratio)
        height = round(image.height * resize_ratio)
        size = [width, height]
        image = TF.center_crop(image, size)
        return image, height, width

    first_frame, height, width = aspect_ratio_resize(first_frame, pipe)
    if last_frame.size != first_frame.size:
        last_frame, _, _ = center_crop_resize(last_frame, height, width)

    output = pipe(
        image=first_frame, last_image=last_frame, prompt=prompt, height=height, width=width, guidance_scale=5.5
    ).frames[0]
    video_path = "wan_output.mp4"
    export_to_video(output, video_path, fps=16)
    return video_path

iface = gr.Interface(
    fn=generate_video,
    inputs=[
        gr.Textbox(label="First Frame URL"),
        gr.Textbox(label="Last Frame URL"),
        gr.Textbox(label="Prompt")
    ],
    outputs=gr.Video(label="Generated Video"),
    title="Wan2.1 FLF2V Video Generator"
)

iface.launch()