• Cross-platform: Windows, Mac and Linux
• Multi-language support
• Subtitle provider login support
• No hotkeys required: opening a video will automatically trigger subtitles to download
  (Only when the right subtitles are not yet present)

This Lua script uses the Python program subliminal to download subtitles. Make sure you have both installed:  

pip install subliminal

1. Copy autosub.lua into:

   OS	Path
   Windows	[Drive]:\Users\[User]\AppData\Roaming\mpv\scripts
   Mac/Linux	~/.config/mpv/scripts/

   mkdir ~/.config/mpv/scripts
   cat > ~/.config/mpv/scripts/autosub.lua
   [Paste script contents and CTRL+D]

2. Specify the correct subliminal location for your system:

   • To determine the correct path, use:

     OS	App	Command
     Windows	Command Prompt	where subliminal
     Mac/Linux	Terminal	which subliminal

   • Copy this path to the subliminal variable at the start of the script:

     local subliminal = '/path/to/your/subliminal'

     On Windows, the backslashes in the path need to be escaped, e.g.:
     C:\\Users\\Administrator\\AppData\\Local\\Programs\\Python\\Python37\\Scripts\\subliminal.exe

• Optionally change the subtitle languages / ISO codes.

This script is under the MIT License, so you are free to modify and adapt this script to your needs:
check out the MPV Lua API for more information.

If you find yourself unable to find the correct subtitles for some niche movies/series, you might be interested in the submod command line tool I've written to manually correct subtitle timing.

Inspired by selsta's and fullmetalsheep's autosub scripts.