命令：

pip install --extra-index-url https://rospypi.github.io/simple/ rosbag

安装结果截图：

现在启动python导入rosbag库会看到：

Failed to load Python extension for LZ4 support. LZ4 compression will not be available.

 安装roslz4

pip install roslz4 --extra-index-url https://rospypi.github.io/simple/

参考文献：

1.https://stackoverflow.com/questions/58754968/failed-to-load-python-extension-for-lz4-support-lz4-compression-will-not-be-ava