MPV-射手影音字幕插件

1. put SPlayerSub.py and download_subtitles_using_SPlayer_API.js to ~/.config/mpv/scripts/
2. put mpv.conf to ~/.config/mpv/
3. 打开视频后，按a 开始下载字幕，字幕会下载到视频~/.cache/mpv/目录，并自动加载

refer:

• Scripting language bindings

• 射手影音智能字幕查询API