December 2020
tl;dr: A bag of tricks to train YOLOv3.
This paper and YOLOv4 both starts from YOLOv3 but adopts different methods. YOLOv4 explores extensively recent advances in backbones and data augmentation, while PP-YOLO adopts more training tricks. Their improvements are orthogonal.
The paper is more like a cookbook/recipe, and the focus is how to stack effective tricks that hardly affect efficiency to get better performance.