Download widerface and put it in data/, the directory tree should look like the following:
data
└── widerface
├── wider_face_split
├── WIDER_train
│ └── images
│ ├── 0--Parade
│ └── ...
└── WIDER_val
└── images
├── 0--Parade
├── ...convert the annotations:
python scripts/convert_widerface_to_coco.py --datadir data/widerface --subset all --outdir ./