# Preparing HMDB51

## Introduction

<!-- [DATASET] -->

```BibTeX
@article{Kuehne2011HMDBAL,
  title={HMDB: A large video database for human motion recognition},
  author={Hilde Kuehne and Hueihan Jhuang and E. Garrote and T. Poggio and Thomas Serre},
  journal={2011 International Conference on Computer Vision},
  year={2011},
  pages={2556-2563}
}
```

For basic dataset information, you can refer to the dataset [website](https://serre-lab.clps.brown.edu/resource/hmdb-a-large-human-motion-database/).
Before we start, please make sure that the directory is located at `$MMACTION2/tools/data/hmdb51/`.

To run the bash scripts below, you need to install `unrar`. you can install it by `sudo apt-get install unrar`,
or refer to [this repo](https://github.com/innerlee/setup) by following the usage and taking [`zzunrar.sh`](https://github.com/innerlee/setup/blob/master/zzunrar.sh)
script for easy installation without sudo.

## Step 1. Prepare Annotations

First of all, you can run the following script to prepare annotations.

```shell
bash download_annotations.sh
```

## Step 2. Prepare Videos

Then, you can run the following script to prepare videos.

```shell
bash download_videos.sh
```

## 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/en/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/hmdb51_extracted/
ln -s /mnt/SSD/hmdb51_extracted/ ../../../data/hmdb51/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
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
bash extract_rgb_frames_opencv.sh
```

If both are required, run the following script to extract frames using "tvl1" algorithm.

```shell
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
bash generate_rawframes_filelist.sh
bash generate_videos_filelist.sh
```

## Step 5. Check Directory Structure

After the whole data process for HMDB51 preparation,
you will get the rawframes (RGB + Flow), videos and annotation files for HMDB51.

In the context of the whole project (for HMDB51 only), the folder structure will look like:

```
mmaction2
├── mmaction
├── tools
├── configs
├── data
│   ├── hmdb51
│   │   ├── hmdb51_{train,val}_split_{1,2,3}_rawframes.txt
│   │   ├── hmdb51_{train,val}_split_{1,2,3}_videos.txt
│   │   ├── annotations
│   │   ├── videos
│   │   │   ├── brush_hair
│   │   │   │   ├── April_09_brush_hair_u_nm_np1_ba_goo_0.avi

│   │   │   ├── wave
│   │   │   │   ├── 20060723sfjffbartsinger_wave_f_cm_np1_ba_med_0.avi
│   │   ├── rawframes
│   │   │   ├── brush_hair
│   │   │   │   ├── April_09_brush_hair_u_nm_np1_ba_goo_0
│   │   │   │   │   ├── img_00001.jpg
│   │   │   │   │   ├── img_00002.jpg
│   │   │   │   │   ├── ...
│   │   │   │   │   ├── flow_x_00001.jpg
│   │   │   │   │   ├── flow_x_00002.jpg
│   │   │   │   │   ├── ...
│   │   │   │   │   ├── flow_y_00001.jpg
│   │   │   │   │   ├── flow_y_00002.jpg
│   │   │   ├── ...
│   │   │   ├── wave
│   │   │   │   ├── 20060723sfjffbartsinger_wave_f_cm_np1_ba_med_0
│   │   │   │   ├── ...
│   │   │   │   ├── winKen_wave_u_cm_np1_ri_bad_1

```

For training and evaluating on HMDB51, please refer to \[getting_started.md\](/docs/en/getting_started.md).