--- license: other license_name: ltx-2.x-community-license license_link: LICENSE.md base_model: Lightricks/LTX-2.5 base_model_relation: quantized library_name: comfyui pipeline_tag: text-to-video tags: - ltx-2.5 - comfyui - quantization - int8 - convrot - nvfp4 - text-to-video - image-to-video - audio-video --- # LTX-2.5 ComfyUI Quants by DDB Community quantizations of the official split-weight [`Lightricks/LTX-2.5`](https://huggingface.co/Lightricks/LTX-2.5) release for ComfyUI. The repository contains matching Dev and Distilled diffusion transformers, the LTX-specific Gemma-4 12B text encoder with projection, and an experimental quantized Distilled LoRA. These are community conversions, not official Lightricks or ComfyOrg releases. > **Pre-release validation boundary:** all 10 current artifacts passed structural and > deep DDB-qanalyse validation. The four final transformer files were recognized > by ComfyUI on a physical RTX 4090, the NVFP4 Gemma-4/LTX text encoder passed > a real tokenize + forward + dual-projection smoke, and the quantized-LoRA > runtime passed a real GPU tensor-dequantization smoke. Equal-seed > prompt-to-decoded-video and audio quality A/B tests are still pending, so no > perceptual-quality ranking is claimed yet. ## Naming - `dev` is the regular configurable LTX-2.5 route. - `distilled` is the official fixed **8-step / CFG 1** route. - Transformer `int8-convrot` is the quality-retaining INT8 profile: 1,435 searched INT8 matrices, ConvRot/Hadamard group size 256, and five BF16 sensitivity islands selected by DDB-qanalyse. - Transformer `nvfp4` is the compact profile: 1,425 searched NVFP4 matrices and fifteen BF16 sensitivity islands. Ada uses the supported fallback path; native NVFP4 acceleration is a Blackwell path. - The transformer lineup now has only these two profiles. Existing text-encoder and LoRA profile names are unchanged. - Quantized LoRAs use a DDB descriptor/runtime; stock ComfyUI LoRA loading is **not** claimed for them. ## Choose a profile Choose one transformer row. Dev and Distilled use the same two-profile layout; download only the route you intend to use. | Profile | Dev transformer | Distilled transformer | Matching existing TE | Optional existing Distilled LoRA | Intended route | |---|---:|---:|---:|---:|---| | **int8-convrot** | [20.152 GiB](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/diffusion_models/ltx-2.5-22b-dev-transformer-int8-convrot.safetensors?download=true) | [20.152 GiB](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/diffusion_models/ltx-2.5-22b-distilled-transformer-int8-convrot.safetensors?download=true) | [`int8`](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/text_encoders/gemma4-12b-with-proj-ltx-2.5-int8.safetensors?download=true) | [`int8`](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/loras/ltx-2.5-22b-distilled-lora-450-int8.safetensors?download=true) | Highest retained transformer precision; use ComfyUI offload on a 24 GiB GPU. | | **nvfp4** | [12.641 GiB](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/diffusion_models/ltx-2.5-22b-dev-transformer-nvfp4.safetensors?download=true) | [12.641 GiB](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/diffusion_models/ltx-2.5-22b-distilled-transformer-nvfp4.safetensors?download=true) | [`nvfp4`](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/text_encoders/gemma4-12b-with-proj-ltx-2.5-nvfp4.safetensors?download=true) | [`nvfp4`](https://huggingface.co/DmitryDB/LTX-2.5-ComfyUI-Quants/resolve/main/loras/ltx-2.5-22b-distilled-lora-450-nvfp4.safetensors?download=true) | Smallest transformer route; supported fallback on RTX 4090 and native acceleration on supported Blackwell hardware. | The retired transformer Lean profile saved only about 127.9 MiB by quantizing five matrices which the source analysis marked as sensitivity islands, so it was removed. File size is not complete-workflow peak VRAM; resolution, frame count, audio, attention, TE, VAEs, upscalers, and offload also matter. ## Dev v2 searched rebuild Both **Dev and Distilled** transformers were rebuilt from their exact official BF16 bytes. The v2 rebuild preserves separate Q/K/V and replaces the old fixed/simple scale path with exhaustive FP32 MSE scale selection: - `int8-convrot`: 101 scale candidates from 1.00 to 0.80 per selected matrix, then stock-compatible INT8 ConvRot g256 storage; - `nvfp4`: 101 scale candidates from 1.00 to 0.50 per 16-value block, stored in the stock Comfy NVFP4 wire format. Every final transformer is bound to its source SHA-256, tensor-schema digest, policy digest, kernel digest, Qfabrik build lock, output SHA-256, and a real stock-ComfyUI load plus quantized-projection smoke on an RTX 4090. ## Quantization layout | Transformer profile | Quantized matrices | BF16 retained matrices | Output tensors | |---|---:|---:|---:| | `int8-convrot` | 1,435 | 5 | 7,219 | | `nvfp4` | 1,425 | 15 | 8,624 | The five INT8 BF16 islands and fifteen NVFP4 islands are identical policy shapes for Dev and Distilled but are independently source-bound. This is a measured quantization/runtime statement, not a perceptual quality ranking. ## Measured runtime checks All four final physical transformer files passed: | Check | Hardware/runtime | Result | |---|---|---| | Dev `int8-convrot` / `nvfp4` stock load and projection | RTX 4090, ComfyUI embedded Python | PASS | | Distilled `int8-convrot` / `nvfp4` stock load and projection | RTX 4090, ComfyUI embedded Python | PASS | These are exact loader/kernel checks. Complete equal-seed decoded-video/audio quality and end-to-end peak-VRAM comparisons remain pending. ## Installation and required upstream components Place the selected files in: ```text ComfyUI/models/diffusion_models/.safetensors ComfyUI/models/text_encoders/.safetensors ComfyUI/models/loras/.safetensors ``` A complete workflow still needs the official BF16 auxiliary files. They are deliberately not requantized or duplicated here: - `vae/ltx-2.5-audio-vae-bf16.safetensors` - `vae/ltx-2.5-video-vae-bf16.safetensors` - `vae/ltx-2.5-video-vae-conv-bf16.safetensors` - the official `latent_upscale_models/` files used by the chosen workflow; - the official duration model/head when required by the workflow. Use a current ComfyUI installation and start from the official [`LTX-2.5 example workflows`](https://github.com/Lightricks/ComfyUI-LTXVideo/tree/master/example_workflows/2.5). The quantized transformers and text encoders are ComfyUI-format weights; use in `ltx-pipelines` is not claimed. ## Which route should I download? - **Normal configurable generation:** Dev transformer. - **Fast official 8-step / CFG 1 route:** Distilled transformer. - **Best retained transformer precision:** `int8-convrot`. - **Smallest transformer route:** `nvfp4`. Text encoder and optional experimental LoRA selection remains a separate choice; their existing profile filenames were not renamed by this transformer cleanup. ## Validation and reproducibility Every released artifact has exact tensor/header, DDB-qanalyse, build-report, byte-size, and SHA-256 evidence. The four v2 transformers additionally include exact source and tensor-schema locks, deterministic policy and kernel digests, effective Qfabrik build locks, and stock-Comfy runtime-smoke reports. - Transformer converters: DDB searched v2 converters in `recipes/v2/tools/`. - Transformer INT8 search: FP32 per-matrix MSE grid, 101 candidates, ConvRot g256. - Transformer NVFP4 search: FP32 per-block MSE grid, 101 candidates, block 16. - Existing TE/LoRA conversion evidence remains under its original recipe paths. - Official quantized files were comparison inputs only, never policy authority. ## Known limits - A prompt-to-decoded-video/audio perceptual A/B has not yet been completed. - Full workflow VRAM and speed numbers for 16 GiB, 24 GiB, and Blackwell systems are not yet published. - Quantized LoRAs require the matching DDB runtime and are not stock-ComfyUI compatibility claims. - The removed transformer paths remain recoverable from repository history. ## License and attribution Use is subject to the included **LTX-2.x Community License Agreement**. Read [`LICENSE.md`](LICENSE.md) before using or redistributing the files. The base model is by Lightricks. This community conversion is not affiliated with or endorsed by Lightricks or ComfyOrg. Original copyright and notices remain with their owners.