llm-semantic-router / multi-modal-embed-large

multi-modal-embed-large

multi-modal-embed-large is the large production multimodal embedding model from the llm-semantic-router project.

It is designed for routing, retrieval, and cross-modal matching across text, image, and audio rather than for generative chat. The model uses a tri-encoder architecture with separate text, image, and audio towers projected into one shared embedding space.

Purpose

This release exists to provide a large multimodal embedding model for production systems where inputs may arrive as text, screenshots or images, and audio. It is built for semantic routing, multimodal retrieval, and cross-modal similarity.

What Is In This Repository

This repository contains the minimum artifacts needed to load and run the exported model:

• model.pt : trained weights for the final exported model
• config.json : model configuration and encoder names
• src/hf_st_mm/... : the Python source package used to construct and run the tri-encoder
• README.md : this model card, including usage examples and validation summary

This is not a generic Hugging Face Transformers checkpoint with a built-in auto-class loader. It is a packaged custom PyTorch model export.

Advantages And Innovation

Most multimodal models are optimized for generation, captioning, or chat. This model is optimized for embeddings and operational use.

What is different here:

• map text, image, and audio into one shared semantic space
• support routing and retrieval instead of text generation
• preserve a strong multilingual text backbone
• use stronger modality-specific encoders instead of forcing every modality into one monolithic checkpoint
• support production training and evaluation on cached shard datasets

Model Overview

This release packages the large routing-grade tri-encoder trained in PyTorch with the server training stack from this project.

Architecture:

• text encoder: llm-semantic-router/mmbert-embed-32k-2d-matryoshka
• image encoder: google/siglip2-so400m-patch14-384
• audio encoder: openai/whisper-medium
• shared embedding dimension: 768
• max text length: 32768

Training characteristics:

• objective: cached multiple negatives ranking loss
• training stack: PyTorch + Accelerate
• target hardware: AMD MI300X
• data pipeline: cached tensor shards with sequential shard loading and worker-local prefetch

How To Use It

Installation

pip install torch sentence-transformers transformers accelerate safetensors pillow librosa soundfile huggingface_hub

Python Usage

The simplest way to use the model is to download the repository snapshot, load the packaged source code, and then encode one or more modality-tagged items.

import json
import os
import sys

import torch
from huggingface_hub import snapshot_download

repo_id = "llm-semantic-router/multi-modal-embed-large"
local_dir = snapshot_download(repo_id=repo_id)

sys.path.insert(0, os.path.join(local_dir, "src"))

from hf_st_mm.data import PairItem
from hf_st_mm.model import MultiModalSentenceEmbedder

with open(os.path.join(local_dir, "config.json"), "r", encoding="utf-8") as handle:
    cfg = json.load(handle)

model = MultiModalSentenceEmbedder(
    text_encoder_name=cfg["model"]["text_encoder_name"],
    image_encoder_name=cfg["model"]["image_encoder_name"],
    audio_encoder_name=cfg["model"]["audio_encoder_name"],
    embedding_dim=int(cfg["model"]["embedding_dim"]),
    max_text_length=int(cfg["model"]["max_text_length"]),
)
state_dict = torch.load(os.path.join(local_dir, "model.pt"), map_location="cpu")
model.load_state_dict(state_dict)
model.eval()

items = [
  PairItem(modality="text", value="route this request to the billing team"),
    PairItem(modality="image", value="/path/to/screenshot.png"),
    PairItem(modality="audio", value="/path/to/call.wav"),
]

with torch.no_grad():
    embeddings = model.encode_items(items)

print(embeddings.shape)  # [3, 768]

import torch.nn.functional as F

query = PairItem(modality="text", value="refund request for wrong charge")
candidate = PairItem(modality="audio", value="/path/to/refund_call.wav")

with torch.no_grad():
    embs = model.encode_items([query, candidate])

similarity = F.cosine_similarity(embs[0:1], embs[1:2]).item()
print(f"similarity={similarity:.4f}")

Validation Snapshot

At upload time, the final export was evaluated with the repository's tri-encoder evaluator.

• eval_loss : 0.389702
• eval_top1 : 0.861707

Practical Notes

• Text inputs can be provided as raw strings or tokenized features.
• Image and audio inputs can be provided as file paths.
• Cached tensor payloads are supported by the training stack, but the simplest inference path is to use file paths or raw text.
• This release is intended for production retrieval and routing use cases rather than for instruction-following or caption generation.

Limitations

• This is a custom tri-encoder export, not a standard Transformers auto-class package.
• Inference currently relies on the packaged hf_st_mm source code.
• The validation metrics reported here come from the repository's cached retrieval validation path, not from a public benchmark leaderboard.

Training Code

Training and evaluation code live in the server training project that produced this checkpoint.

• trainer: scripts/train_st_multimodal.py
• evaluator: scripts/evaluate_tri_encoder.py
• model: src/hf_st_mm/model.py