README.md

---
license: apache-2.0
language:
- en
library_name: transformers
pipeline_tag: video-text-to-text
tags:
- moss_vl
- feature-extraction
- Base
- Video-Understanding
- Image-Understanding
- MOSS-VL
- OpenMOSS
- multimodal
- video
- vision-language
- custom_code
---

<p align="center">
  <img src="assets/logo.png" width="300" alt="MOSS-VL"/>
</p>

# MOSS-VL-Base-0708

## Introduction

MOSS-VL-Base-0708 is the foundation checkpoint of the MOSS-VL 0708 release, part of the OpenMOSS ecosystem for open visual understanding.

Built through multimodal pretraining only, this checkpoint serves as a high-capacity offline multimodal base model. It provides strong general-purpose visual-language representations across image and video inputs, and is intended primarily as the base model for supervised fine-tuning, alignment, and domain adaptation.

The 0708 release keeps the MOSS-VL cross-attention design and a 256K text context window while refreshing the data and pretraining recipe for stronger offline multimodal foundations.

Specifically, the pretraining pipeline follows four progressive stages:

- Stage 1: Vision-language alignment
- Stage 2: Large-scale multimodal pretraining
- Stage 3: High-quality multimodal pretraining
- Stage 4: Annealing and long-context extension

## Highlights

- Strong foundation model: provides general visual-language representations for image, video, and text inputs.
- Native dynamic resolution: processes images and video frames at their original aspect ratios and resolutions.
- Native interleaved image and video inputs: supports mixed image/video/text sequences in a unified pipeline.
- Open base checkpoint: designed for continued pretraining, supervised fine-tuning, alignment, and domain adaptation.

## Model Architecture

MOSS-VL-Base-0708 adopts a cross-attention-based vision-language architecture that decouples visual encoding from language reasoning. The model processes images, videos, and text in a unified pipeline and uses cross-attention layers to connect language tokens with visual representations.

<p align="center">
  <img src="assets/architecture.png" alt="MOSS-VL Architecture" width="100%"/>
</p>

Key configuration details:

| Item | Value |
| --- | --- |
| Parameters | 11B |
| Tensor type | BF16 |
| Context length | 256K |
| Vision patch size | 16 |
| Temporal patch size | 1 |
| Default video FPS | 1.0 |
| Default max video frames | 256 |

## Absolute Timestamps

For video inputs, MOSS-VL injects absolute timestamps alongside sampled frames. This helps the base model learn event order, duration, pacing, and temporal localization instead of relying only on frame order.

## Cross-attention RoPE (XRoPE)

MOSS-VL uses Cross-attention Rotary Position Embedding (XRoPE), which maps text tokens and visual patches into a unified three-dimensional coordinate space defined by Time (t), Height (h), and Width (w). This gives the model a consistent positional representation for image and video understanding.

## Model Performance

MOSS-VL-Base-0708 is intended as a pretrained foundation checkpoint for offline multimodal understanding and model adaptation. Detailed benchmark tables for the 0708 release will be maintained in the MOSS-VL project resources.

<p align="center">
  <img src="assets/benchmark-offline.png" alt="MOSS-VL Offline Benchmark" width="100%"/>
</p>

For the previous public base checkpoint, see [MOSS-VL-Base-0408](https://huggingface.co/OpenMOSS-Team/MOSS-VL-Base-0408).

## Quickstart

### Installation

Clone the MOSS-VL repository and install the project requirements:

```bash
git clone https://github.com/OpenMOSS/MOSS-VL.git
cd MOSS-VL
conda create -n moss_vl python=3.12 pip -y
conda activate moss_vl
pip install -i https://pypi.org/simple --no-build-isolation -r requirements.txt
```

### Load Model

```python
import torch
from transformers import AutoModelForCausalLM, AutoProcessor

checkpoint = "OpenMOSS-Team/MOSS-VL-Base-0708"

processor = AutoProcessor.from_pretrained(
    checkpoint,
    trust_remote_code=True,
    frame_extract_num_threads=1,
)
model = AutoModelForCausalLM.from_pretrained(
    checkpoint,
    trust_remote_code=True,
    device_map="auto",
    torch_dtype=torch.bfloat16,
    attn_implementation="flash_attention_2",
)
```

### Run Inference

<details>
<summary><b>Single-image Inference</b></summary>

```python
image_path = "data/example_image.jpg"

text = model.offline_image_generate(
    processor,
    prompt="",
    image=image_path,
    shortest_edge=4096,
    longest_edge=16777216,
    multi_image_max_pixels=201326592,
    patch_size=16,
    temporal_patch_size=1,
    merge_size=2,
    image_mean=[0.5, 0.5, 0.5],
    image_std=[0.5, 0.5, 0.5],
    max_new_tokens=256,
    temperature=1.0,
    top_k=50,
    top_p=1.0,
    repetition_penalty=1.0,
    do_sample=False,
    vision_chunked_length=64,
)

print(text)
```

</details>

<details>
<summary><b>Single-video Inference</b></summary>

```python
video_path = "data/example_video.mp4"

text = model.offline_video_generate(
    processor,
    prompt="",
    video=video_path,
    shortest_edge=4096,
    longest_edge=16777216,
    video_max_pixels=201326592,
    patch_size=16,
    temporal_patch_size=1,
    merge_size=2,
    video_fps=1.0,
    min_frames=1,
    max_frames=256,
    num_extract_threads=4,
    image_mean=[0.5, 0.5, 0.5],
    image_std=[0.5, 0.5, 0.5],
    max_new_tokens=256,
    temperature=1.0,
    top_k=50,
    top_p=1.0,
    repetition_penalty=1.0,
    do_sample=False,
    vision_chunked_length=64,
)

print(text)
```

</details>

<details>
<summary><b>Batched Offline Inference</b></summary>

`offline_batch_generate` accepts independent image/video/text queries. Queries in the same batch should share the same `media_kwargs` and `generate_kwargs`.

```python
queries = [
    {
        "images": ["data/sample_a.jpg"],
        "videos": [],
        "generate_kwargs": {
            "temperature": 1.0,
            "top_k": 50,
            "top_p": 1.0,
            "max_new_tokens": 256,
            "repetition_penalty": 1.0,
            "do_sample": False,
        },
    },
    {
        "images": [],
        "videos": ["data/sample_b.mp4"],
        "media_kwargs": {
            "video_fps": 1.0,
            "min_frames": 8,
            "max_frames": 256,
        },
        "generate_kwargs": {
            "temperature": 1.0,
            "top_k": 50,
            "top_p": 1.0,
            "max_new_tokens": 256,
            "repetition_penalty": 1.0,
            "do_sample": False,
        },
    },
]

with torch.no_grad():
    result = model.offline_batch_generate(
        processor,
        queries,
        vision_chunked_length=64,
    )

texts = [item["text"] for item in result["results"]]
print(texts)
```

</details>

## Related Checkpoints

| Model | Parameters | Context | Usage | Hugging Face |
| --- | ---: | ---: | --- | --- |
| MOSS-VL-Realtime | 11B | 256K | Realtime streaming video interaction | https://huggingface.co/OpenMOSS-Team/MOSS-VL-Realtime |
| MOSS-VL-Instruct | 11B | 256K | Offline multimodal instruction following | https://huggingface.co/OpenMOSS-Team/MOSS-VL-Instruct-0708 |
| MOSS-VL-Base | 11B | 256K | Continued pretraining and fine-tuning | https://huggingface.co/OpenMOSS-Team/MOSS-VL-Base-0708 |
| MOSS-VL-Instruct-0408 | 11B | 256K | Previous instruction-tuned checkpoint | https://huggingface.co/OpenMOSS-Team/MOSS-VL-Instruct-0408 |
| MOSS-VL-Base-0408 | 11B | 256K | Previous base checkpoint | https://huggingface.co/OpenMOSS-Team/MOSS-VL-Base-0408 |

## Limitations and Future Work

MOSS-VL-Base-0708 is a pretrained base checkpoint. It is not instruction-tuned, so applied use cases should generally fine-tune or align it before using it as an assistant-style model.

We are continuing to improve OCR and document understanding, extremely long video understanding, mathematical reasoning, code reasoning, RL post-training, and broader task-specific evaluations for future MOSS-VL releases.

## Citation

```bibtex
@misc{moss_vl_2026,
  title         = {{MOSS-VL Technical Report}},
  author        = {OpenMOSS Team},
  year          = {2026},
  howpublished  = {\url{https://github.com/OpenMOSS/MOSS-VL}},
  note          = {GitHub repository}
}
```