Automated PR - 2026-01-05
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# LTX-2 Pipelines
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High-level pipeline implementations for generating audio-video content with Lightricks' **LTX-2** model. This package provides ready-to-use pipelines for text-to-video, image-to-video, video-to-video, and keyframe interpolation tasks.
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Pipelines are built using building blocks from [`ltx-core`](../ltx-core/) (schedulers, guiders, noisers, patchifiers) and handle the complete inference flow including model loading, encoding, decoding, and file I/O.
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---
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## 📋 Overview
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LTX-2 Pipelines provides production-ready implementations that abstract away the complexity of the diffusion process, model loading, and memory management. Each pipeline is optimized for specific use cases and offers different trade-offs between speed, quality, and memory usage.
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**Key Features:**
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- 🎬 **Multiple Pipeline Types**: Text-to-video, image-to-video, video-to-video, and keyframe interpolation
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- ⚡ **Optimized Performance**: Support for FP8 transformers, gradient estimation, and memory optimization
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- 🎯 **Production Ready**: Two-stage pipelines for best quality output
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- 🔧 **LoRA Support**: Easy integration with trained LoRA adapters
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- 📦 **Self-Contained**: Handles model loading, encoding, decoding, and file I/O
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- 🚀 **CLI Support**: All pipelines can be run as command-line scripts
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---
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## 🚀 Quick Start
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`ltx-pipelines` provides ready-made inference pipelines for text-to-video, image-to-video, video-to-video, and keyframe interpolation. Built using building blocks from [`ltx-core`](../ltx-core/), these pipelines handle the complete inference flow including model loading, encoding, decoding, and file I/O.
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## 🔧 Installation
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```bash
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# From the repository root
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uv sync --frozen
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# Or install as a package
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pip install -e packages/ltx-pipelines
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```
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### Running Pipelines
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All pipelines can be run directly from the command line. Each pipeline module is executable:
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```bash
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# Run a pipeline (example: two-stage text-to-video)
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python -m ltx_pipelines.ti2vid_two_stages \
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--checkpoint-path path/to/checkpoint.safetensors \
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--distilled-lora-path path/to/distilled_lora.safetensors \
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--spatial-upsampler-path path/to/upsampler.safetensors \
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--gemma-root path/to/gemma \
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--prompt "A beautiful sunset over the ocean" \
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--output-path output.mp4
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# View all available options for any pipeline
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python -m ltx_pipelines.ti2vid_two_stages --help
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```
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Available pipeline modules:
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- `ltx_pipelines.ti2vid_two_stages` - Two-stage text-to-video (recommended)
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- `ltx_pipelines.ti2vid_one_stage` - Single-stage text-to-video
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- `ltx_pipelines.distilled` - Fast distilled pipeline
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- `ltx_pipelines.ic_lora` - Video-to-video with IC-LoRA
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- `ltx_pipelines.keyframe_interpolation` - Keyframe interpolation
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Use `--help` with any pipeline module to see all available options and parameters.
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---
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## 🎯 Pipeline Selection Guide
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### Quick Decision Tree
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```text
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Do you need to condition on existing images/videos?
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├─ YES → Do you have reference videos for video-to-video?
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│ ├─ YES → Use ICLoraPipeline
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│ └─ NO → Do you have keyframe images to interpolate?
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│ ├─ YES → Use KeyframeInterpolationPipeline
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│ └─ NO → Use ICLoraPipeline (image conditioning only)
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│
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└─ NO → Text-to-video only
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├─ Do you need best quality?
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│ └─ YES → Use TI2VidTwoStagesPipeline (recommended for production)
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│
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└─ Do you need fastest inference?
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└─ YES → Use DistilledPipeline (with 8 predefined sigmas)
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```
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> **Note:** [`TI2VidOneStagePipeline`](src/ltx_pipelines/ti2vid_one_stage.py) is primarily for educational purposes. For best quality, use two-stage pipelines ([`TI2VidTwoStagesPipeline`](src/ltx_pipelines/ti2vid_two_stages.py), [`ICLoraPipeline`](src/ltx_pipelines/ic_lora.py), [`KeyframeInterpolationPipeline`](src/ltx_pipelines/keyframe_interpolation.py), or [`DistilledPipeline`](src/ltx_pipelines/distilled.py)).
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### Features Comparison
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| Pipeline | Stages | CFG | Upsampling | Conditioning | Best For |
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| -------- | ------ | --- | ---------- | ------------- | -------- |
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| **TI2VidTwoStagesPipeline** | 2 | ✅ | ✅ | Image | **Production quality** (recommended) |
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| **TI2VidOneStagePipeline** | 1 | ✅ | ❌ | Image | Educational, prototyping |
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| **DistilledPipeline** | 2 | ❌ | ✅ | Image | Fastest inference (8 sigmas) |
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| **ICLoraPipeline** | 2 | ✅ | ✅ | Image + Video | Video-to-video transformations |
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| **KeyframeInterpolationPipeline** | 2 | ✅ | ✅ | Keyframes | Animation, interpolation |
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---
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## 📦 Available Pipelines
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### 1. TI2VidTwoStagesPipeline
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**Best for:** High-quality text-to-video generation with upsampling. **Recommended for production use.**
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**Source**: [`src/ltx_pipelines/ti2vid_two_stages.py`](src/ltx_pipelines/ti2vid_two_stages.py)
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Two-stage generation: Stage 1 generates low-resolution video with CFG guidance, Stage 2 upsamples to 2x resolution with distilled LoRA refinement. Supports image conditioning. Highest quality output, slower than one-stage but significantly better quality.
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**Use when:** Production-quality video generation, higher resolution needed, quality over speed, text-to-video with image conditioning.
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---
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### 2. TI2VidOneStagePipeline
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**Best for:** Educational purposes and quick prototyping.
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**Source**: [`src/ltx_pipelines/ti2vid_one_stage.py`](src/ltx_pipelines/ti2vid_one_stage.py)
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> **⚠️ Important:** This pipeline is primarily for educational purposes. For production-quality results, use `TI2VidTwoStagesPipeline` or other two-stage pipelines.
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Single-stage generation (no upsampling) with CFG guidance and image conditioning support. Faster inference but lower resolution output (typically 512x768).
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**Use when:** Learning how the pipeline works, quick prototyping, testing, or when high resolution is not needed.
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---
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### 3. DistilledPipeline
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**Best for:** Fastest inference with good quality using a distilled model with predefined sigma schedule.
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**Source**: [`src/ltx_pipelines/distilled.py`](src/ltx_pipelines/distilled.py)
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Two-stage generation with 8 predefined sigmas (8 steps in stage 1, 4 steps in stage 2). No CFG guidance required. Fastest inference among all pipelines. Supports image conditioning. Requires spatial upsampler.
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**Use when:** Fastest inference is critical, batch processing many videos, or when you have a distilled model checkpoint.
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---
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### 4. ICLoraPipeline
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**Best for:** Video-to-video and image-to-video transformations using IC-LoRA.
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**Source**: [`src/ltx_pipelines/ic_lora.py`](src/ltx_pipelines/ic_lora.py)
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Two-stage generation with IC-LoRA support. Can condition on reference videos (video-to-video) or images at specific frames. CFG guidance in stage 1, upsampling in stage 2. Requires IC-LoRA trained model.
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**Use when:** Video-to-video transformations, image-to-video with strong control, or when you have reference videos to guide generation.
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---
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### 5. KeyframeInterpolationPipeline
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**Best for:** Generating videos by interpolating between keyframe images.
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**Source**: [`src/ltx_pipelines/keyframe_interpolation.py`](src/ltx_pipelines/keyframe_interpolation.py)
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Two-stage generation with keyframe interpolation. Uses guiding latents (additive conditioning) instead of replacing latents for smoother transitions. CFG guidance in stage 1, upsampling in stage 2.
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**Use when:** You have keyframe images and want to interpolate between them, creating smooth transitions, or animation/motion interpolation tasks.
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---
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## 🎨 Conditioning Types
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Pipelines use different conditioning methods from [`ltx-core`](../ltx-core/) for controlling generation. See the [ltx-core conditioning documentation](../ltx-core/README.md#conditioning--control) for details.
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### Image Conditioning
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All pipelines support image conditioning, but with different methods:
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- **Replacing Latents** ([`image_conditionings_by_replacing_latent`](src/ltx_pipelines/utils/helpers.py)):
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- Used by: `TI2VidOneStagePipeline`, `TI2VidTwoStagesPipeline`, `DistilledPipeline`, `ICLoraPipeline`
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- Replaces the latent at a specific frame with the encoded image
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- Strong control over specific frames
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- **Guiding Latents** ([`image_conditionings_by_adding_guiding_latent`](src/ltx_pipelines/utils/helpers.py)):
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- Used by: `KeyframeInterpolationPipeline`
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- Adds the image as a guiding signal rather than replacing
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- Better for smooth interpolation between keyframes
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### Video Conditioning
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- **Video Conditioning** (ICLoraPipeline only):
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- Conditions on entire reference videos
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- Useful for video-to-video transformations
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- Uses `VideoConditionByKeyframeIndex` from [`ltx-core`](../ltx-core/)
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---
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## ⚡ Optimization Tips
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### Memory Optimization
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**FP8 Transformer (Lower Memory Footprint):**
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For smaller GPU memory footprint, use the `enable-fp8` flag and use the `PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True` environment variable.
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**CLI:**
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```bash
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PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True python -m ltx_pipelines.ti2vid_one_stage --enable-fp8 --checkpoint-path=...
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```
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**Programmatically:**
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When authoring custom scripts, pass the `fp8transformer` flag to pipeline classes or construct your own by analogy:
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```python
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pipeline = TI2VidTwoStagesPipeline(
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checkpoint_path=ltx_model_path,
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distilled_lora_path=distilled_lora_path,
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distilled_lora_strength=0.6,
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spatial_upsampler_path=upsampler_path,
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gemma_root=gemma_root_path,
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loras=[],
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fp8transformer=True,
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)
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pipeline(...)
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```
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You still need to use `PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True` when launching:
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```bash
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PYTORCH_CUDA_ALLOC_CONF=expandable_segments:True python my_denoising_pipeline.py
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```
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**Memory Cleanup Between Stages:**
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By default, pipelines clean GPU memory (especially transformer weights) between stages. If you have enough memory, you can skip this cleanup to reduce running time:
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```python
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# In pipeline implementations, memory cleanup happens automatically
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# between stages. For custom pipelines, you can skip:
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# utils.cleanup_memory() # Comment out if you have enough VRAM
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```
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### Denoising Loop Optimization
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**Gradient Estimation Denoising Loop:**
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Instead of the standard Euler denoising loop, you can use gradient estimation for fewer steps (~20-30 instead of 40):
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```python
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from ltx_pipelines.utils.helpers import gradient_estimating_euler_denoising_loop
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# Use gradient estimation denoising loop
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def denoising_loop(sigmas, video_state, audio_state, stepper):
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return gradient_estimating_euler_denoising_loop(
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sigmas=sigmas,
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video_state=video_state,
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audio_state=audio_state,
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stepper=stepper,
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denoise_fn=your_denoise_function,
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ge_gamma=2.0, # Gradient estimation coefficient
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)
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```
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This allows you to use **20-30 steps instead of 40** while maintaining quality. The gradient estimation function is available in [`pipeline_utils.py`](src/ltx_pipelines/utils/helpers.py).
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---
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## 🔧 Requirements
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- **LTX-2 Model Checkpoint** - Local `.safetensors` file
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- **Gemma Text Encoder** - Local Gemma model directory
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- **Spatial Upscaler** - Required for two-stage pipelines (except one-stage)
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- **Distilled LoRA** - Required for two-stage pipelines (except one-stage and distilled)
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---
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## 📖 Example: Image-to-Video
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```python
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from ltx_pipelines.ti2vid_two_stages import TI2VidTwoStagesPipeline
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pipeline = TI2VidTwoStagesPipeline(
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checkpoint_path="/path/to/checkpoint.safetensors",
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distilled_lora_path="/path/to/distilled_lora.safetensors",
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spatial_upsampler_path="/path/to/upsampler.safetensors",
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gemma_root="/path/to/gemma",
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loras=[],
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)
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# Generate video from image
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pipeline(
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prompt="A serene landscape with mountains in the background",
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output_path="output.mp4",
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seed=42,
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height=512,
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width=768,
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num_frames=121,
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frame_rate=25.0,
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num_inference_steps=40,
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cfg_guidance_scale=3.0,
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images=[("input_image.jpg", 0, 1.0)], # Image at frame 0, strength 1.0
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)
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```
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---
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## 🔗 Related Projects
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- **[LTX-Core](../ltx-core/)** - Core model implementation and inference components (schedulers, guiders, noisers, patchifiers)
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- **[LTX-Trainer](../ltx-trainer/)** - Training and fine-tuning tools
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