diffusers/scripts/convert_ltx_to_diffusers.py

import argparse
from typing import Any, Dict

import torch
from safetensors.torch import load_file
from transformers import T5EncoderModel, T5Tokenizer

from diffusers import AutoencoderKLLTXVideo, FlowMatchEulerDiscreteScheduler, LTXPipeline, LTXVideoTransformer3DModel


def remove_keys_(key: str, state_dict: Dict[str, Any]):
    state_dict.pop(key)


TOKENIZER_MAX_LENGTH = 128

TRANSFORMER_KEYS_RENAME_DICT = {
    "patchify_proj": "proj_in",
    "adaln_single": "time_embed",
    "q_norm": "norm_q",
    "k_norm": "norm_k",
}

TRANSFORMER_SPECIAL_KEYS_REMAP = {}

VAE_KEYS_RENAME_DICT = {
    # decoder
    "up_blocks.0": "mid_block",
    "up_blocks.1": "up_blocks.0",
    "up_blocks.2": "up_blocks.1.upsamplers.0",
    "up_blocks.3": "up_blocks.1",
    "up_blocks.4": "up_blocks.2.conv_in",
    "up_blocks.5": "up_blocks.2.upsamplers.0",
    "up_blocks.6": "up_blocks.2",
    "up_blocks.7": "up_blocks.3.conv_in",
    "up_blocks.8": "up_blocks.3.upsamplers.0",
    "up_blocks.9": "up_blocks.3",
    # encoder
    "down_blocks.0": "down_blocks.0",
    "down_blocks.1": "down_blocks.0.downsamplers.0",
    "down_blocks.2": "down_blocks.0.conv_out",
    "down_blocks.3": "down_blocks.1",
    "down_blocks.4": "down_blocks.1.downsamplers.0",
    "down_blocks.5": "down_blocks.1.conv_out",
    "down_blocks.6": "down_blocks.2",
    "down_blocks.7": "down_blocks.2.downsamplers.0",
    "down_blocks.8": "down_blocks.3",
    "down_blocks.9": "mid_block",
    # common
    "conv_shortcut": "conv_shortcut.conv",
    "res_blocks": "resnets",
    "norm3.norm": "norm3",
    "per_channel_statistics.mean-of-means": "latents_mean",
    "per_channel_statistics.std-of-means": "latents_std",
}

VAE_SPECIAL_KEYS_REMAP = {
    "per_channel_statistics.channel": remove_keys_,
    "per_channel_statistics.mean-of-means": remove_keys_,
    "per_channel_statistics.mean-of-stds": remove_keys_,
}


def get_state_dict(saved_dict: Dict[str, Any]) -> Dict[str, Any]:
    state_dict = saved_dict
    if "model" in saved_dict.keys():
        state_dict = state_dict["model"]
    if "module" in saved_dict.keys():
        state_dict = state_dict["module"]
    if "state_dict" in saved_dict.keys():
        state_dict = state_dict["state_dict"]
    return state_dict


def update_state_dict_inplace(state_dict: Dict[str, Any], old_key: str, new_key: str) -> Dict[str, Any]:
    state_dict[new_key] = state_dict.pop(old_key)


def convert_transformer(
    ckpt_path: str,
    dtype: torch.dtype,
):
    PREFIX_KEY = ""

    original_state_dict = get_state_dict(load_file(ckpt_path))
    transformer = LTXVideoTransformer3DModel().to(dtype=dtype)

    for key in list(original_state_dict.keys()):
        new_key = key[len(PREFIX_KEY) :]
        for replace_key, rename_key in TRANSFORMER_KEYS_RENAME_DICT.items():
            new_key = new_key.replace(replace_key, rename_key)
        update_state_dict_inplace(original_state_dict, key, new_key)

    for key in list(original_state_dict.keys()):
        for special_key, handler_fn_inplace in TRANSFORMER_SPECIAL_KEYS_REMAP.items():
            if special_key not in key:
                continue
            handler_fn_inplace(key, original_state_dict)

    transformer.load_state_dict(original_state_dict, strict=True)
    return transformer


def convert_vae(ckpt_path: str, dtype: torch.dtype):
    original_state_dict = get_state_dict(load_file(ckpt_path))
    vae = AutoencoderKLLTXVideo().to(dtype=dtype)

    for key in list(original_state_dict.keys()):
        new_key = key[:]
        for replace_key, rename_key in VAE_KEYS_RENAME_DICT.items():
            new_key = new_key.replace(replace_key, rename_key)
        update_state_dict_inplace(original_state_dict, key, new_key)

    for key in list(original_state_dict.keys()):
        for special_key, handler_fn_inplace in VAE_SPECIAL_KEYS_REMAP.items():
            if special_key not in key:
                continue
            handler_fn_inplace(key, original_state_dict)

    vae.load_state_dict(original_state_dict, strict=True)
    return vae


def get_args():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--transformer_ckpt_path", type=str, default=None, help="Path to original transformer checkpoint"
    )
    parser.add_argument("--vae_ckpt_path", type=str, default=None, help="Path to original vae checkpoint")
    parser.add_argument(
        "--text_encoder_cache_dir", type=str, default=None, help="Path to text encoder cache directory"
    )
    parser.add_argument(
        "--typecast_text_encoder",
        action="store_true",
        default=False,
        help="Whether or not to apply fp16/bf16 precision to text_encoder",
    )
    parser.add_argument("--save_pipeline", action="store_true")
    parser.add_argument("--output_path", type=str, required=True, help="Path where converted model should be saved")
    parser.add_argument("--dtype", default="fp32", help="Torch dtype to save the model in.")
    return parser.parse_args()


DTYPE_MAPPING = {
    "fp32": torch.float32,
    "fp16": torch.float16,
    "bf16": torch.bfloat16,
}

VARIANT_MAPPING = {
    "fp32": None,
    "fp16": "fp16",
    "bf16": "bf16",
}


if __name__ == "__main__":
    args = get_args()

    transformer = None
    dtype = DTYPE_MAPPING[args.dtype]
    variant = VARIANT_MAPPING[args.dtype]

    if args.save_pipeline:
        assert args.transformer_ckpt_path is not None and args.vae_ckpt_path is not None

    if args.transformer_ckpt_path is not None:
        transformer: LTXVideoTransformer3DModel = convert_transformer(args.transformer_ckpt_path, dtype)
        if not args.save_pipeline:
            transformer.save_pretrained(
                args.output_path, safe_serialization=True, max_shard_size="5GB", variant=variant
            )

    if args.vae_ckpt_path is not None:
        vae: AutoencoderKLLTXVideo = convert_vae(args.vae_ckpt_path, dtype)
        if not args.save_pipeline:
            vae.save_pretrained(args.output_path, safe_serialization=True, max_shard_size="5GB", variant=variant)

    if args.save_pipeline:
        text_encoder_id = "google/t5-v1_1-xxl"
        tokenizer = T5Tokenizer.from_pretrained(text_encoder_id, model_max_length=TOKENIZER_MAX_LENGTH)
        text_encoder = T5EncoderModel.from_pretrained(text_encoder_id, cache_dir=args.text_encoder_cache_dir)

        if args.typecast_text_encoder:
            text_encoder = text_encoder.to(dtype=dtype)

        # Apparently, the conversion does not work anymore without this :shrug:
        for param in text_encoder.parameters():
            param.data = param.data.contiguous()

        scheduler = FlowMatchEulerDiscreteScheduler(
            use_dynamic_shifting=True,
            base_shift=0.95,
            max_shift=2.05,
            base_image_seq_len=1024,
            max_image_seq_len=4096,
            shift_terminal=0.1,
        )

        pipe = LTXPipeline(
            scheduler=scheduler,
            vae=vae,
            text_encoder=text_encoder,
            tokenizer=tokenizer,
            transformer=transformer,
        )

        pipe.save_pretrained(args.output_path, safe_serialization=True, variant=variant, max_shard_size="5GB")