mpv-auto-sub-sync

Automatically synchronizes the active subtitle track to the selected audio track when mpv opens a local file. Synchronization runs in the background using ffsubsync so no key press or menu is required.

It supports external and embedded SRT, ASS, and SSA subtitles. The original subtitle remains unchanged, and temporary files are removed when playback ends.

Nix

Add the flake:

inputs.mpv-auto-sub-sync.url = "github:greyxp1/mpv-auto-sub-sync";

With Home Manager, include the package in mpv's scripts:

programs.mpv = {
  enable = true;
  scripts = [
    inputs.mpv-auto-sub-sync.packages.${pkgs.stdenv.hostPlatform.system}.default
  ];
  config.watch-later-options-remove = "sid";
};

The Nix package supports x86-64 and ARM64 Linux and includes the compact official ffsubsync binary and FFmpeg runtime integration.

Without Home Manager, pass the script package when wrapping mpv:

pkgs.mpv.override {
  scripts = [
    inputs.mpv-auto-sub-sync.packages.${pkgs.stdenv.hostPlatform.system}.default
  ];
}

Other Linux distributions

Install ffmpeg and ffsubsync, then copy auto-sub-sync.lua into ~/.config/mpv/scripts/.