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+# Preparing Something-Something V2
+
+## Introduction
+
+<!-- [DATASET] -->
+
+```BibTeX
+@misc{goyal2017something,
+      title={The "something something" video database for learning and evaluating visual common sense},
+      author={Raghav Goyal and Samira Ebrahimi Kahou and Vincent Michalski and Joanna Materzyńska and Susanne Westphal and Heuna Kim and Valentin Haenel and Ingo Fruend and Peter Yianilos and Moritz Mueller-Freitag and Florian Hoppe and Christian Thurau and Ingo Bax and Roland Memisevic},
+      year={2017},
+      eprint={1706.04261},
+      archivePrefix={arXiv},
+      primaryClass={cs.CV}
+}
+```
+
+For basic dataset information, you can refer to the dataset [website](https://20bn.com/datasets/something-something/v2).
+Before we start, please make sure that the directory is located at `$MMACTION2/tools/data/sthv2/`.
+
+## Step 1. Prepare Annotations
+
+First of all, you have to sign in and download annotations to `$MMACTION2/data/sthv2/annotations` on the official [website](https://20bn.com/datasets/something-something/v2).
+
+## Step 2. Prepare Videos
+
+Then, you can download all data parts to `$MMACTION2/data/sthv2/` and use the following command to uncompress.
+
+```shell
+cd $MMACTION2/data/sthv2/
+cat 20bn-something-something-v2-?? | tar zx
+cd $MMACTION2/tools/data/sthv2/
+```
+
+## Step 3. Extract RGB and Flow
+
+This part is **optional** if you only want to use the video loader.
+
+Before extracting, please refer to [install.md](/docs/install.md) for installing [denseflow](https://github.com/open-mmlab/denseflow).
+
+If you have plenty of SSD space, then we recommend extracting frames there for better I/O performance.
+
+You can run the following script to soft link SSD.
+
+```shell
+# execute these two line (Assume the SSD is mounted at "/mnt/SSD/")
+mkdir /mnt/SSD/sthv2_extracted/
+ln -s /mnt/SSD/sthv2_extracted/ ../../../data/sthv2/rawframes
+```
+
+If you only want to play with RGB frames (since extracting optical flow can be time-consuming), consider running the following script to extract **RGB-only** frames using denseflow.
+
+```shell
+cd $MMACTION2/tools/data/sthv2/
+bash extract_rgb_frames.sh
+```
+
+If you didn't install denseflow, you can still extract RGB frames using OpenCV by the following script, but it will keep the original size of the images.
+
+```shell
+cd $MMACTION2/tools/data/sthv2/
+bash extract_rgb_frames_opencv.sh
+```
+
+If both are required, run the following script to extract frames.
+
+```shell
+cd $MMACTION2/tools/data/sthv2/
+bash extract_frames.sh
+```
+
+## Step 4. Generate File List
+
+you can run the follow script to generate file list in the format of rawframes and videos.
+
+```shell
+cd $MMACTION2/tools/data/sthv2/
+bash generate_{rawframes, videos}_filelist.sh
+```
+
+## Step 5. Check Directory Structure
+
+After the whole data process for Something-Something V2 preparation,
+you will get the rawframes (RGB + Flow), videos and annotation files for Something-Something V2.
+
+In the context of the whole project (for Something-Something V2 only), the folder structure will look like:
+
+```
+mmaction2
+├── mmaction
+├── tools
+├── configs
+├── data
+│   ├── sthv2
+│   │   ├── sthv2_{train,val}_list_rawframes.txt
+│   │   ├── sthv2_{train,val}_list_videos.txt
+│   │   ├── annotations
+│   |   ├── videos
+│   |   |   ├── 1.mp4
+│   |   |   ├── 2.mp4
+│   |   |   ├──...
+│   |   ├── rawframes
+│   |   |   ├── 1
+│   |   |   |   ├── img_00001.jpg
+│   |   |   |   ├── img_00002.jpg
+│   |   |   |   ├── ...
+│   |   |   |   ├── flow_x_00001.jpg
+│   |   |   |   ├── flow_x_00002.jpg
+│   |   |   |   ├── ...
+│   |   |   |   ├── flow_y_00001.jpg
+│   |   |   |   ├── flow_y_00002.jpg
+│   |   |   |   ├── ...
+│   |   |   ├── 2
+│   |   |   ├── ...
+
+```
+
+For training and evaluating on Something-Something V2, please refer to [getting_started.md](/docs/getting_started.md).