MR. Video: "MapReduce" is the Principle for Long Video Understanding [NeurIPS 2025]

June 18, 2026 · View on GitHub

[arXiv] [Dataset]

MR. Video is an agentic long-video understanding framework built around a MapReduce pattern: dense short-clip perception followed by global aggregation and reasoning. This repository contains the released code for running the question-answering agent pipeline from precomputed MR. Video captions.

Code Layout

configs/                 Model/provider configuration.
scripts/                 Dataset runners for LVBench, EgoSchema, and VideoMME.
eval/                    Evaluation scripts for saved predictions.
videoagent/              Core MR. Video agent, prompts, model clients, and video reader.
assets/                  Figures used in this README.
misc/API_KEYS.example.json

Setup

git clone https://github.com/ziqipang/MR-Video.git
cd MR-Video

python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

Create an API-key file:

cp misc/API_KEYS.example.json misc/API_KEYS.json

Then edit misc/API_KEYS.json:

{
  "openai": "your-openai-api-key",
  "gemini": "your-gemini-api-key"
}

You can also skip the JSON file and use environment variables:

export OPENAI_API_KEY=your-openai-api-key
export GEMINI_API_KEY=your-gemini-api-key

Data Layout

By default, the scripts look for data under datasets/. You can either place files there or pass custom paths through command-line arguments or environment variables.

Recommended local layout:

datasets/
  lvbench/
    video_info.meta.jsonl
    videos/
      <lvbench_video>.mp4
      <lvbench_video>.json
    captions/
      <video_id>.json
  egoschema/
    egoschema_val_data.jsonl
    videos/
      <video_id>.mp4
    captions/
      <video_id>.json
  videomme/
    video_mme_long.jsonl
    videos/
      <video_id>.mp4
    captions/
      <video_id>.json

Caption files are available from Hugging Face:

For custom locations, either pass arguments:

python -m scripts.run_lvbench \
  --lvbench_path /path/to/lvbench/videos \
  --lvbench_meta /path/to/video_info.meta.jsonl \
  --caption_dir /path/to/lvbench_captions

or set environment variables:

export LVBENCH_PATH=/path/to/lvbench/videos
export LVBENCH_META=/path/to/video_info.meta.jsonl
export LVBENCH_CAPTION_DIR=/path/to/lvbench_captions

Path overrides used by the runners:

Benchmark	CLI arguments	Environment variables
LVBench	`--lvbench_path`, `--lvbench_meta`, `--caption_dir`	`LVBENCH_PATH`, `LVBENCH_META`, `LVBENCH_CAPTION_DIR`
EgoSchema	`--egoschema_path`, `--egoschema_meta`, `--caption_dir`	`EGOSCHEMA_PATH`, `EGOSCHEMA_META`, `EGOSCHEMA_CAPTION_DIR`
VideoMME	`--videomme_path`, `--videomme_meta`, `--caption_dir`	`VIDEOMME_PATH`, `VIDEOMME_META`, `VIDEOMME_CAPTION_DIR`

Shared overrides include MRVIDEO_CONFIG, MRVIDEO_API_KEYS, MRVIDEO_OUTPUT_DIR, MRVIDEO_EXP_NAME, and MRVIDEO_LOG_DIR.

Smoke Test

Start with one video before launching a full benchmark run:

python -m scripts.run_lvbench --limit 1 --exp_name smoke_lvbench

If you already know a valid video ID, target it directly:

python -m scripts.run_lvbench --video_ids VIDEO_ID --exp_name smoke_lvbench

The same smoke-test flags are available for the other runners:

python -m scripts.run_egoschema --limit 1 --exp_name smoke_egoschema
python -m scripts.run_videomme --limit 1 --exp_name smoke_videomme

Run Benchmarks

LVBench:

python -m scripts.run_lvbench --exp_name mrvideo_lvbench

EgoSchema:

python -m scripts.run_egoschema --exp_name mrvideo_egoschema

VideoMME:

python -m scripts.run_videomme --exp_name mrvideo_videomme

Useful shared options:

--config configs/gpt4o_gemini.yaml
--api_key misc/API_KEYS.json
--output_dir data/<benchmark>
--num_processes 4 --process_index 0

Outputs are saved as reusable intermediate files:

data/<benchmark>/<exp_name>/<video_id>/
  1_1_user_intention/
  1_2_user_intention/
  2_1_1_goal_proposal/
  2_1_2_perception_results/
  2_2_answer_generation/

Re-running the same command resumes from existing intermediate JSON files.

Evaluate

python -m eval.lvbench --exp_name mrvideo_lvbench
python -m eval.egoschema --exp_name mrvideo_egoschema
python -m eval.videomme --exp_name mrvideo_videomme

If your predictions are outside the default data/<benchmark> folder, pass --output_dir or set MRVIDEO_OUTPUT_DIR.

Citation

If you find this work useful in your research, please cite:

@article{pang2025mrvideo,
  title={MR. Video: "MapReduce" is the Principle for Long Video Understanding},
  author={Pang, Ziqi and Wang, Yu-Xiong},
  journal={arXiv preprint arXiv:2504.16082},
  year={2025}
}