HERMES

[ACL 2026] KV Cache as Hierarchical Memory for Efficient Streaming Video Understanding

🔥 News

• [2026.04.06] HERMES is accepted to ACL 2026 Main 🎉
• [2026.03.23] Full code released!
• [2025.01.23] HERMES reached #3 Paper of the day on Hugging Face Daily Papers!
• [2025.01.21] HERMES is available on arXiv.

🛠️ Installation

For LLaVA model inference:

conda create -n hermes-llava python=3.12 -y
conda activate hermes-llava
pip install -r requirements_llava.txt
pip install flash-attn --no-build-isolation

For Qwen2.5-VL model inference:

conda create -n hermes-qwen python=3.12 -y
conda activate hermes-qwen
pip install -r requirements_qwen.txt
pip install flash-attn --no-build-isolation

📦 Preparation

Model Preparation

Create a models directory and download the model weights from HuggingFace:

mkdir models

We support the following models (choose one or more):

Model Family	Model	HuggingFace Link
LLaVA-OneVision	llava-onevision-qwen2-0.5b-ov-hf	llava-hf/llava-onevision-qwen2-0.5b-ov-hf
LLaVA-OneVision	llava-onevision-qwen2-7b-ov-hf	llava-hf/llava-onevision-qwen2-7b-ov-hf
LLaVA-OneVision	llava-onevision-qwen2-72b-ov-hf	llava-hf/llava-onevision-qwen2-72b-ov-hf
Qwen2.5-VL	Qwen2.5-VL-3B-Instruct	Qwen/Qwen2.5-VL-3B-Instruct
Qwen2.5-VL	Qwen2.5-VL-7B-Instruct	Qwen/Qwen2.5-VL-7B-Instruct
Qwen2.5-VL	Qwen2.5-VL-32B-Instruct	Qwen/Qwen2.5-VL-32B-Instruct

Data Preparation

Download the benchmark videos from their official sources and place them according to the paths specified in the annotation files:

Streaming Benchmarks:

Benchmark	Video Path	Official Source
StreamingBench	/data/streamingbench/videos/	🤗 StreamingBench
OVO-Bench	/data/ovobench/videos/	🤗 OVO-Bench
RVS-Ego	/data/rvs/ego/videos/	🤗 RVS
RVS-Movie	/data/rvs/movie/videos/	🤗 RVS

Offline Benchmarks:

Benchmark	Video Path	Official Source
VideoMME	/data/videomme/videos/	🤗 VideoMME
MVBench	/data/mvbench/videos/	🤗 MVBench
EgoSchema	/data/egoschema/videos/	🤗 EgoSchema

The annotation JSON files contain the same information as officially provided, with formatting adjustments to adapt to our codebase.

After preparation, the project structure should look like this:

HERMES/
├── asset/
│   └── logo.png
├── data/
│   ├── egoschema/
│   │   ├── videos/
│   │   └── egoschema.json
│   ├── mvbench/
│   │   ├── videos/
│   │   └── mvbench.json
│   ├── ovobench/
│   │   ├── videos/
│   │   └── ovobench_realtime_backeward.json
│   ├── rvs/
│   │   ├── ego/
│   │   │   ├── videos/
│   │   │   └── ego4d_oe.json
│   │   └── movie/
│   │       ├── videos/
│   │       └── movienet_oe.json
│   ├── streamingbench/
│   │   ├── videos/
│   │   └── streamingbench_realtime.json
│   └── videomme/
│       ├── videos/
│       └── videomme.json
├── eval/
│   ├── eval_multiple_choice.py
│   └── eval_open_ended.py
├── inference/
│   ├── abstract_hermes.py
│   ├── llavaov_hermes.py
│   ├── qwenvl_hermes.py
│   ├── reindex_1d.py
│   └── reindex_3d.py
├── models/
│   ├── llava-onevision-qwen2-0.5b-ov-hf/
│   ├── llava-onevision-qwen2-7b-ov-hf/
│   ├── llava-onevision-qwen2-72b-ov-hf/
│   ├── Qwen2.5-VL-3B-Instruct/
│   ├── Qwen2.5-VL-7B-Instruct/
│   └── Qwen2.5-VL-32B-Instruct/
├── scripts/
│   └── run_infer.sh
├── video_qa/
│   ├── base.py
│   ├── hermes_vqa.py
│   └── run_infer.py
├── LICENSE
├── README.md
├── requirements_llava.txt
└── requirements_qwen.txt

🚀 Inference

Simply run the inference script:

bash scripts/run_infer.sh

Here is the content of scripts/run_infer.sh:

export PYTHONPATH=$(cd "$(dirname "$0")/.." && pwd):$PYTHONPATH

num_chunks=8
model=llava_ov_7b
dataset=streamingbench

python video_qa/run_infer.py \
    --num_chunks $num_chunks \
    --model ${model} \
    --dataset ${dataset} \
    --sample_fps 0.5 \
    --kv_size 6000

Arguments:

Argument	Description
model	Model to use. Options: llava_ov_0.5b, llava_ov_7b, llava_ov_72b, qwen2.5_vl_3b, qwen2.5_vl_7b, qwen2.5_vl_32b
dataset	Benchmark dataset. Options: videomme, mvbench, egoschema, rvs_ego, rvs_movie, ovobench, streamingbench
num_chunks	Number of parallel processes for evaluation, typically set to the number of GPUs
sample_fps	Frame sampling rate (frames per second) from the video
kv_size	Maximum KV cache size for HERMES hierarchical memory management
only_eval	If set, skip inference and only run evaluation on existing results

📊 Evaluation

The evaluation scripts compute metrics on the inference results:

• Multiple-choice benchmarks (VideoMME, MVBench, EgoSchema, OVBench, StreamingBench) are evaluated by eval/eval_multiple_choice.py, which takes a subcommand as its first argument:

Subcommand	Description	Used by
general	Compute overall accuracy, task-specific breakdown (auto-detects OVBench / StreamingBench), and prediction error analysis	MVBench, OVBench, StreamingBench, VideoMME
videomme	Report accuracy broken down by video duration (short / medium / long)	VideoMME
egoschema	Generate EgoSchema submission CSV file	EgoSchema

python eval/eval_multiple_choice.py general --results_path results/llava_ov_7b/streamingbench/fps0.5-kv6000/results.csv

• Open-ended benchmarks (RVS-Ego, RVS-Movie) are evaluated by eval/eval_open_ended.py, which uses GPT for answer scoring:

python eval/eval_open_ended.py \
    --pred_path results/llava_ov_7b/rvs_ego/fps0.5-kv6000/results.csv \
    --output_dir results/llava_ov_7b/rvs_ego/fps0.5-kv6000/tmp \
    --output_json results/llava_ov_7b/rvs_ego/fps0.5-kv6000/results.json

📧 Contact

For any questions regarding the paper or the technical implementation, please feel free to contact haowei.zhang123@gmail.com

🙏 Acknowledgements

Our codebase is built upon ReKV. We gratefully acknowledge their contributions to the community.

📝 Citation

If you find our work useful for research, please cite our paper and give us a precious star 😄:

@misc{zhang2026hermeskvcachehierarchical,
      title={HERMES: KV Cache as Hierarchical Memory for Efficient Streaming Video Understanding}, 
      author={Haowei Zhang and Shudong Yang and Jinlan Fu and See-Kiong Ng and Xipeng Qiu},
      year={2026},
      eprint={2601.14724},
      archivePrefix={arXiv},
      primaryClass={cs.CV},
      url={https://arxiv.org/abs/2601.14724}, 
}