Model-Optimizer/examples/diffusers/distillation

LTX-2 Distillation Training with ModelOpt

Warning

Third-Party License Notice — LTX-2

LTX-2 is a third-party model and set of packages developed and provided by Lightricks. LTX-2 is not covered by the Apache 2.0 license that governs NVIDIA Model Optimizer.

By installing and using LTX-2 packages (ltx-core, ltx-pipelines, ltx-trainer) with NVIDIA Model Optimizer, you must comply with the LTX Community License Agreement.

Any derivative models or fine-tuned weights produced from LTX-2 using NVIDIA Model Optimizer (including quantized or distilled checkpoints) remain subject to the LTX Community License Agreement and are not covered by Apache 2.0.

Knowledge distillation for LTX-2 DiT models using NVIDIA ModelOpt. A frozen teacher guides a trainable student through a combined loss:

L_total = α × L_task + (1-α) × L_distill

Currently supported:

• Quantization-Aware Distillation (QAD) — student uses ModelOpt fake quantization

Planned:

• Sparsity-Aware Distillation (SAD) — student uses ModelOpt sparsity

Installation

# From the distillation example directory
cd examples/diffusers/distillation

# Install Model-Optimizer (from repo root)
pip install -e ../../..

# Install all dependencies (ltx-trainer, ltx-core, ltx-pipelines, omegaconf)
pip install -r requirements.txt

Quick Start

1. Prepare Your Dataset

Use the ltx-trainer preprocessing to extract latents and text embeddings:

python -m ltx_trainer.preprocess \
    --input_dir /path/to/videos \
    --output_dir /path/to/preprocessed \
    --model_path /path/to/ltx2/checkpoint.safetensors

2. Configure

Copy and edit the example config:

cp configs/distillation_example.yaml configs/my_experiment.yaml

Key settings to update:

model:
  model_path: "/path/to/ltx2/checkpoint.safetensors"
  text_encoder_path: "/path/to/gemma/model"

data:
  preprocessed_data_root: "/path/to/preprocessed/data"

distillation:
  distillation_alpha: 0.5       # 1.0 = pure task loss, 0.0 = pure distillation
  quant_cfg: "FP8_DEFAULT_CFG"  # or INT8_DEFAULT_CFG, NVFP4_DEFAULT_CFG, null

# IMPORTANT: disable ltx-trainer's built-in quantization
acceleration:
  quantization: null

3. Run Training

Single GPU

python distillation_trainer.py --config configs/my_experiment.yaml

Multi-GPU (Single Node) with Accelerate

accelerate launch \
    --config_file configs/accelerate/fsdp.yaml \
    --num_processes 8 \
    distillation_trainer.py --config configs/my_experiment.yaml

Multi-node Training with Accelerate

To launch on multiple nodes, make sure to set the following environment variables on each node:

• NUM_NODES: Total number of nodes
• GPUS_PER_NODE: Number of GPUs per node
• NODE_RANK: Unique rank/index of this node (0-based)
• MASTER_ADDR: IP address of the master node (rank 0)
• MASTER_PORT: Communication port (e.g., 29500)

Then run this (on every node):

accelerate launch \
    --config_file configs/accelerate/fsdp.yaml \
    --num_machines $NUM_NODES \
    --num_processes $((NUM_NODES * GPUS_PER_NODE)) \
    --machine_rank $NODE_RANK \
    --main_process_ip $MASTER_ADDR \
    --main_process_port $MASTER_PORT \
    distillation_trainer.py --config configs/my_experiment.yaml

Config overrides can be passed via CLI using dotted notation:

accelerate launch ... distillation_trainer.py \
    --config configs/my_experiment.yaml \
    ++distillation.distillation_alpha=0.6 \
    ++distillation.quant_cfg=INT8_DEFAULT_CFG \
    ++optimization.learning_rate=1e-5

Configuration Reference

Calibration

Before training begins, calibration runs full denoising inference to collect activation statistics for accurate quantizer scales. This is cached as a step-0 checkpoint and reused on subsequent runs.

Parameter	Default	Description
calibration_prompts_file	null	Text file with one prompt per line. Use the HuggingFace dataset 'Gustavosta/Stable-Diffusion-Prompts' if null.
calibration_size	128	Number of prompts (each runs a full denoising loop)
calibration_n_steps	30	Denoising steps per prompt
calibration_guidance_scale	4.0	CFG scale (should match inference-time)

Checkpoint Resume

Parameter	Default	Description
resume_from_checkpoint	null	"latest" to auto-detect, or explicit path
must_save_by	null	Minutes after which to save and exit (for Slurm time limits)
restore_quantized_checkpoint	null	Restore a pre-quantized model (skips calibration)
save_quantized_checkpoint	null	Path to save the final quantized model

Custom Quantization Configs

To define custom quantization configs, add entries to CUSTOM_QUANT_CONFIGS in distillation_trainer.py:

CUSTOM_QUANT_CONFIGS["MY_FP8_CFG"] = {
    "quant_cfg": mtq.FP8_DEFAULT_CFG["quant_cfg"],
    "algorithm": "max",
}

Then reference it in your YAML: quant_cfg: MY_FP8_CFG.