---
license: other
license_name: sam-license
license_link: https://huggingface.co/facebook/sam3.1/blob/main/LICENSE
library_name: sam3
tags:
  - segmentation
  - sam3
  - sam3.1
  - video
  - multiplex
  - facebookresearch
base_model: facebook/sam3.1
---

# SAM 3.1 — AEmotionStudio Mirror

This is an open mirror of [`facebook/sam3.1`](https://huggingface.co/facebook/sam3.1)
hosted by [Æmotion Studio](https://huggingface.co/AEmotionStudio) so that
`ComfyUI-FFMPEGA` and other downstream tools can auto-download the SAM 3.1
multiplex tracker without users having to accept the gated terms one-by-one.

> ⚠️ **License:** Use of these weights is governed by the upstream SAM License
> (Meta). See [`LICENSE`](LICENSE) — you accept those terms by downloading
> or using the model. This mirror exists solely to make installation
> ergonomic; it is not a relicensing of the model.

## What's here

| File | Size | Notes |
|---|---|---|
| `sam3.1_multiplex.safetensors` | ~3.5 GB | Preferred. Safer, mmap-friendly format. |
| `sam3.1_multiplex.pt` | ~3.5 GB | Upstream `.pt` format — kept for byte-for-byte parity with `facebook/sam3.1`. |
| `tokenizer.json`, `vocab.json`, `merges.txt`, `*config*.json` | small | BPE / processor files SAM 3.1 needs at load time. |

## SAM 3.1 highlights vs SAM 3

- New **multiplex tracker** — joint multi-object tracking via shared memory.
- ~7× faster on multi-object video (~32 FPS vs. ~16 FPS for 128 objects).
- ~½ the VRAM (8 GB → 4 GB in FP16) on the same scenes.
- Unchanged image-detection model — the gains are entirely in the video path.

## Direct use

```python
from sam3.model_builder import build_sam3_multiplex_video_model

model = build_sam3_multiplex_video_model(
    checkpoint_path="/path/to/sam3.1_multiplex.pt",
    load_from_HF=False,
    device="cuda",
)
```

Requires `sam3` from `git+https://github.com/facebookresearch/sam3.git` (a
revision new enough to include `build_sam3_multiplex_video_model`).

## ComfyUI-FFMPEGA

`ComfyUI-FFMPEGA` auto-downloads from this mirror first and falls back to
`facebook/sam3.1` if the mirror is unreachable. Pick `sam_version="sam3.1"`
on the Effects Builder or Load Video Path node to use it.

## Upstream

- Code: <https://github.com/facebookresearch/sam3>
- Original weights: <https://huggingface.co/facebook/sam3.1>
- Paper / blog: see the upstream repo.