Files
Model-Optimizer/examples/diffusers/quantization/calibration.py
T
jingyu-ml 2e43c80609 [2/4] Diffusion Quantized ckpt export (#810)
## What does this PR do?

**Type of change:** New feature <!-- Use one of the following: Bug fix,
new feature, new example, new tests, documentation. -->

**Overview:** 

This MR adds HuggingFace checkpoint export support for LTX‑2 by treating
TI2VidTwoStagesPipeline as a diffusion-like pipeline, exporting only the
stage‑1 transformer (with QKV-fusion-enabled dummy inputs) and falling
back to writing model.safetensors when save_pretrained isn’t available.
It also preserves the original forward in DynamicModule patching
(_forward_pre_dm) so downstream callers can still invoke the pre-patched
forward implementation.

**Changes**

1. Added the calibration & quantization support of the LTX2, even with
FP8 precision.
2. Preserve original forward before `DynamicModule` patching: when
patching forward, we now stash the pre-patched implementation in
`self._forward_pre_dm` (once) so downstream code can still call the
original forward, then re-bind forward to the class implementation. This
is needed for the LTX2 FP8 calibration.
3. Added LTX‑2 HF export path: `export_hf_checkpoint()` now also treats
ltx_pipelines.ti2vid_two_stages.TI2VidTwoStagesPipeline as a
“diffusion-like” object and routes it through
_export_diffusers_checkpoint() (import guarded; no hard dependency).
4. Generalized component discovery: introduced
get_diffusion_components() (aliasing the old get_diffusers_components)
to support non-diffusers pipelines; for LTX‑2 it returns only
stage_1_transformer.
5. Enabled QKV fusion for LTX‑2 backbone: added a model-aware dummy
forward generator (generate_diffusion_dummy_forward_fn) that builds
minimal LTX Modality inputs (including correct timesteps broadcasting)
so shared-input hooks can run and fuse QKV when applicable.
6. Export fallback for non-save_pretrained modules: when a component
lacks save_pretrained (LTX‑2 transformer), export now writes
model.safetensors + minimal config.json instead of pytorch_model.bin.

Plans

- [x] [1/4] Add the basic functionalities to support limited image
models with NVFP4 + FP8, with some refactoring on the previous LLM code
and the diffusers example. PIC: @jingyu-ml
- [x] [2/4] Add support to more video gen models. PIC: @jingyu-ml 
- [ ] [3/4] Add test cases, refactor on the doc, and all related README.
PIC: @jingyu-ml
- [ ] [4/4] Add the final support to ComfyUI. PIC @jingyu-ml 

## Usage
<!-- You can potentially add a usage example below. -->
```bash
python quantize.py --model ltx-2 --format fp4 --batch-size 64 --calib-size 1 --n-steps 40 --extra-param checkpoint_path=/home/scratch.omniml_data_2/jingyux/models/LTX-2/ltx-2-19b-dev-fp8.safetensors --extra-param distilled_lora_path=/home/scratch.omniml_data_2/jingyux/models/LTX-2/ltx-2-19b-distilled-lora-384.safetensors --extra-param spatial_upsampler_path=/home/scratch.omniml_data_2/jingyux/models/LTX-2/ltx-2-spatial-upscaler-x2-1.0.safetensors --extra-param gemma_root=/home/scratch.omniml_data_2/jingyux/models/LTX-2/gemma-3-12b-it-qat-q4_0-unquantized --extra-param fp8transformer=true --hf-ckpt-dir ./ltx2-nvfp4
```

## Testing
<!-- Mention how have you tested your change if applicable. -->

## Before your PR is "*Ready for review*"
<!-- If you haven't finished some of the above items you can still open
`Draft` PR. -->

- **Make sure you read and follow [Contributor
guidelines](https://github.com/NVIDIA/Model-Optimizer/blob/main/CONTRIBUTING.md)**
and your commits are signed.
- **Is this change backward compatible?**: Yes <!--- If No, explain why.
-->
- **Did you write any new necessary tests?**:No
- **Did you add or update any necessary documentation?**:No
- **Did you update
[Changelog](https://github.com/NVIDIA/Model-Optimizer/blob/main/CHANGELOG.rst)?**:No
<!--- Only for new features, API changes, critical bug fixes or bw
breaking changes. -->

## Additional Information
<!-- E.g. related issue. -->

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

## Release Notes

* **New Features**
* Added LTX-2 video model support with complete quantization and export
pipeline integration
* Introduced `--extra-param` CLI option for flexible model configuration
and parameter passing
* Enhanced export capabilities with broader diffusion model
compatibility

* **Chores**
* Changed default model data type from Half to BFloat16 for improved
numerical stability

<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Jingyu Xin <jingyux@nvidia.com>
2026-02-04 10:41:33 +00:00

196 lines
7.9 KiB
Python

# SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from pathlib import Path
from typing import Any
from models_utils import MODEL_DEFAULTS, ModelType
from pipeline_manager import PipelineManager
from quantize_config import CalibrationConfig
from tqdm import tqdm
from utils import load_calib_prompts
class Calibrator:
"""Handles model calibration for quantization."""
def __init__(
self,
pipeline_manager: PipelineManager,
config: CalibrationConfig,
model_type: ModelType,
logger: logging.Logger,
):
"""
Initialize calibrator.
Args:
pipeline_manager: Pipeline manager with main and upsampler pipelines
config: Calibration configuration
model_type: Type of model being calibrated
logger: Logger instance
"""
self.pipeline_manager = pipeline_manager
self.pipe = pipeline_manager.pipe
self.pipe_upsample = pipeline_manager.pipe_upsample
self.config = config
self.model_type = model_type
self.logger = logger
def load_and_batch_prompts(self) -> list[list[str]]:
"""
Load calibration prompts from file.
Returns:
List of batched calibration prompts
"""
self.logger.info(f"Loading calibration prompts from {self.config.prompts_dataset}")
if isinstance(self.config.prompts_dataset, Path):
return load_calib_prompts(
self.config.batch_size,
self.config.prompts_dataset,
)
return load_calib_prompts(
self.config.batch_size,
self.config.prompts_dataset["name"],
self.config.prompts_dataset["split"],
self.config.prompts_dataset["column"],
)
def run_calibration(self, batched_prompts: list[list[str]]) -> None:
"""
Run calibration steps on the pipeline.
Args:
batched_prompts: List of batched calibration prompts
"""
self.logger.info(f"Starting calibration with {self.config.num_batches} batches")
extra_args = MODEL_DEFAULTS.get(self.model_type, {}).get("inference_extra_args", {})
with tqdm(total=self.config.num_batches, desc="Calibration", unit="batch") as pbar:
for i, prompt_batch in enumerate(batched_prompts):
if i >= self.config.num_batches:
break
if self.model_type == ModelType.LTX2:
self._run_ltx2_calibration(prompt_batch, extra_args)
elif self.model_type == ModelType.LTX_VIDEO_DEV:
# Special handling for LTX-Video
self._run_ltx_video_calibration(prompt_batch, extra_args)
elif self.model_type in [ModelType.WAN22_T2V_14b, ModelType.WAN22_T2V_5b]:
# Special handling for WAN video models
self._run_wan_video_calibration(prompt_batch, extra_args)
else:
common_args = {
"prompt": prompt_batch,
"num_inference_steps": self.config.n_steps,
}
self.pipe(**common_args, **extra_args).images
pbar.update(1)
self.logger.debug(f"Completed calibration batch {i + 1}/{self.config.num_batches}")
self.logger.info("Calibration completed successfully")
def _run_wan_video_calibration(
self, prompt_batch: list[str], extra_args: dict[str, Any]
) -> None:
kwargs = {}
kwargs["negative_prompt"] = extra_args["negative_prompt"]
kwargs["height"] = extra_args["height"]
kwargs["width"] = extra_args["width"]
kwargs["num_frames"] = extra_args["num_frames"]
kwargs["guidance_scale"] = extra_args["guidance_scale"]
if "guidance_scale_2" in extra_args:
kwargs["guidance_scale_2"] = extra_args["guidance_scale_2"]
kwargs["num_inference_steps"] = self.config.n_steps
self.pipe(prompt=prompt_batch, **kwargs).frames
def _run_ltx2_calibration(self, prompt_batch: list[str], extra_args: dict[str, Any]) -> None:
from ltx_core.model.video_vae import TilingConfig
prompt = prompt_batch[0]
extra_params = self.pipeline_manager.config.extra_params
kwargs = {
"negative_prompt": extra_args.get(
"negative_prompt", "worst quality, inconsistent motion, blurry, jittery, distorted"
),
"seed": extra_params.get("seed", 0),
"height": extra_params.get("height", extra_args.get("height", 1024)),
"width": extra_params.get("width", extra_args.get("width", 1536)),
"num_frames": extra_params.get("num_frames", extra_args.get("num_frames", 121)),
"frame_rate": extra_params.get("frame_rate", extra_args.get("frame_rate", 24.0)),
"num_inference_steps": self.config.n_steps,
"cfg_guidance_scale": extra_params.get(
"cfg_guidance_scale", extra_args.get("cfg_guidance_scale", 4.0)
),
"images": extra_params.get("images", []),
"tiling_config": extra_params.get("tiling_config", TilingConfig.default()),
}
self.pipe(prompt=prompt, **kwargs)
def _run_ltx_video_calibration(
self, prompt_batch: list[str], extra_args: dict[str, Any]
) -> None:
"""
Run calibration for LTX-Video model using the full multi-stage pipeline.
Args:
prompt_batch: Batch of prompts
extra_args: Model-specific arguments
"""
# Extract specific args for LTX-Video
expected_height = extra_args.get("height", 512)
expected_width = extra_args.get("width", 704)
num_frames = extra_args.get("num_frames", 121)
negative_prompt = extra_args.get(
"negative_prompt", "worst quality, inconsistent motion, blurry, jittery, distorted"
)
def round_to_nearest_resolution_acceptable_by_vae(height, width):
height = height - (height % self.pipe.vae_spatial_compression_ratio)
width = width - (width % self.pipe.vae_spatial_compression_ratio)
return height, width
downscale_factor = 2 / 3
# Part 1: Generate video at smaller resolution
downscaled_height, downscaled_width = (
int(expected_height * downscale_factor),
int(expected_width * downscale_factor),
)
downscaled_height, downscaled_width = round_to_nearest_resolution_acceptable_by_vae(
downscaled_height, downscaled_width
)
# Generate initial latents at lower resolution
latents = self.pipe(
conditions=None,
prompt=prompt_batch,
negative_prompt=negative_prompt,
width=downscaled_width,
height=downscaled_height,
num_frames=num_frames,
num_inference_steps=self.config.n_steps,
output_type="latent",
).frames
# Part 2: Upscale generated video using latent upsampler (if available)
if self.pipe_upsample is not None:
_ = self.pipe_upsample(latents=latents, output_type="latent").frames
# Part 3: Denoise the upscaled video with few steps to improve texture
# However, in this example code, we will omit the upscale step since its optional.