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+# Preparing HVU
+
+## Introduction
+
+<!-- [DATASET] -->
+
+```BibTeX
+@article{Diba2019LargeSH,
+  title={Large Scale Holistic Video Understanding},
+  author={Ali Diba and M. Fayyaz and Vivek Sharma and Manohar Paluri and Jurgen Gall and R. Stiefelhagen and L. Gool},
+  journal={arXiv: Computer Vision and Pattern Recognition},
+  year={2019}
+}
+```
+
+For basic dataset information, please refer to the official [project](https://github.com/holistic-video-understanding/HVU-Dataset/) and the [paper](https://arxiv.org/abs/1904.11451).
+Before we start, please make sure that the directory is located at `$MMACTION2/tools/data/hvu/`.
+
+## Step 1. Prepare Annotations
+
+First of all, you can run the following script to prepare annotations.
+
+```shell
+bash download_annotations.sh
+```
+
+Besides, you need to run the following command to parse the tag list of HVU.
+
+```shell
+python parse_tag_list.py
+```
+
+## Step 2. Prepare Videos
+
+Then, you can run the following script to prepare videos.
+The codes are adapted from the [official crawler](https://github.com/activitynet/ActivityNet/tree/master/Crawler/Kinetics). Note that this might take a long time.
+
+```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/install.md) for installing [denseflow](https://github.com/open-mmlab/denseflow).
+
+You can use the following script to extract both RGB and Flow frames.
+
+```shell
+bash extract_frames.sh
+```
+
+By default, we generate frames with short edge resized to 256.
+More details can be found in [data_preparation](/docs/data_preparation.md)
+
+## Step 4. Generate File List
+
+You can run the follow scripts to generate file list in the format of videos and rawframes, respectively.
+
+```shell
+bash generate_videos_filelist.sh
+# execute the command below when rawframes are ready
+bash generate_rawframes_filelist.sh
+```
+
+## Step 5. Generate File List for Each Individual Tag Categories
+
+This part is **optional** if you don't want to train models on HVU for a specific tag category.
+
+The file list generated in step 4 contains labels of different categories. These file lists can only be
+handled with HVUDataset and used for multi-task learning of different tag categories. The component
+`LoadHVULabel` is needed to load the multi-category tags, and the `HVULoss` should be used to train
+the model.
+
+If you only want to train video recognition models for a specific tag category, i.e. you want to train
+a recognition model on HVU which only handles tags in the category `action`, we recommend you to use
+the following command to generate file lists for the specific tag category. The new list, which only
+contains tags of a specific category, can be handled with `VideoDataset` or `RawframeDataset`. The
+recognition models can be trained with `BCELossWithLogits`.
+
+The following command generates file list for the tag category ${category}, note that the tag category you
+specified should be in the 6 tag categories available in HVU: ['action', 'attribute', 'concept', 'event',
+'object', 'scene'].
+
+```shell
+python generate_sub_file_list.py path/to/filelist.json ${category}
+```
+
+The filename of the generated file list for ${category} is generated by replacing `hvu` in the original
+filename with `hvu_${category}`. For example, if the original filename is `hvu_train.json`, the filename
+of the file list for action is `hvu_action_train.json`.
+
+## Step 6. Folder Structure
+
+After the whole data pipeline for HVU preparation.
+you can get the rawframes (RGB + Flow), videos and annotation files for HVU.
+
+In the context of the whole project (for HVU only), the full folder structure will look like:
+
+```
+mmaction2
+├── mmaction
+├── tools
+├── configs
+├── data
+│   ├── hvu
+│   │   ├── hvu_train_video.json
+│   │   ├── hvu_val_video.json
+│   │   ├── hvu_train.json
+│   │   ├── hvu_val.json
+│   │   ├── annotations
+│   │   ├── videos_train
+│   │   │   ├── OLpWTpTC4P8_000570_000670.mp4
+│   │   │   ├── xsPKW4tZZBc_002330_002430.mp4
+│   │   │   ├── ...
+│   │   ├── videos_val
+│   │   ├── rawframes_train
+│   │   ├── rawframes_val
+
+```
+
+For training and evaluating on HVU, please refer to [getting_started](/docs/getting_started.md).