[ChronoEdit] support multiple loras

[zhangjiewu]

This PR adds support for multiple LoRAs in the ChronoEdit pipeline.

Available LoRAs:

• nvidia/ChronoEdit-14B-Diffusers-Upscaler-Lora
• nvidia/ChronoEdit-14B-Diffusers-Paint-Brush-Lora

cc: @sayakpaul @yiyixuxu @asomoza

Usage

import torch
import numpy as np
from diffusers import AutoencoderKLWan, ChronoEditTransformer3DModel, ChronoEditPipeline
from diffusers.schedulers import UniPCMultistepScheduler
from diffusers.utils import export_to_video, load_image
from transformers import CLIPVisionModel
from PIL import Image

model_id = "nvidia/ChronoEdit-14B-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)
transformer = ChronoEditTransformer3DModel.from_pretrained(model_id, subfolder="transformer", torch_dtype=torch.bfloat16)
pipe = ChronoEditPipeline.from_pretrained(model_id, image_encoder=image_encoder, transformer=transformer, vae=vae, torch_dtype=torch.bfloat16)
pipe.load_lora_weights("nvidia/ChronoEdit-14B-Diffusers-Paint-Brush-Lora", weight_name="paintbrush_lora_diffusers.safetensors", adapter_name="paintbrush")
pipe.load_lora_weights("nvidia/ChronoEdit-14B-Diffusers", weight_name="lora/chronoedit_distill_lora.safetensors", adapter_name="distill")
pipe.set_adapters(["paintbrush", "distill"], adapter_weights=[1.0, 1.0])
pipe.scheduler = UniPCMultistepScheduler.from_config(pipe.scheduler.config, flow_shift=2.0)
pipe.to("cuda")

image = load_image(
    "https://raw.githubusercontent.com/nv-tlabs/ChronoEdit/refs/heads/main/assets/images/input_paintbrush.png"
)
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
print("width", width, "height", height)
image = image.resize((width, height))
prompt = (
    "Turn the pencil sketch in the image into an actual object that is consistent with the image’s content. The user wants to change the sketch to a crown and a hat."
)

output = pipe(
    image=image,
    prompt=prompt,
    height=height,
    width=width,
    num_frames=5,
    num_inference_steps=8,
    guidance_scale=1.0,
    enable_temporal_reasoning=False,
    num_temporal_reasoning_steps=0,
).frames[0]
export_to_video(output, "output.mp4", fps=16)
Image.fromarray((output[-1] * 255).clip(0, 255).astype("uint8")).save("output_1.png")

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