yolo34py + AlexeyAB的坑

yolo原作者pjreddie不再更新了，yolo v4 是AlexeyAB的fork出品。
曾經用yolo34py API+ official libdarknet.so，但把darknet轉成AlexeyAB版本後會出錯，貌似用AlexeyAB的darknet.py也會出錯。
原因是free_network 的API不同。
解決辨法可以參考https://github.com/AlexeyAB/darknet/issues/3467
2 approachs:

1. modify free_network, compile new so -> the darknet binary might be broken 我改了原用的free_network成_free_network, 然後加free_network給yolo34py用
2. add api_free_network and change API(darknet.py or yolo34py) -> not compatible with pjreddie

object/pointer construction也跟official不同，比較難兼容…今後如果要用yolov4，大概直接拋棄pjreddie和yolo34py了

YOLOv4 vs CenterNet

The CenterNet used in Yolo v4 is NOT CenterNet: Objects as Points, which is the base of TTFNet. darknet implement CenterNet: Triplet So..currently there is not comparison between TTFNet/ CenterNet vs YOLOv4
Looking for TTFNet implement to darknet TTFnet: 10x Training Time Reduction · Issue #4690 · AlexeyAB/darknet