{
  pkgs,
  lib,
  mkAliases,
  ...
}:

let
  ffmpegExe = lib.getExe pkgs.ffmpeg;

  aliases = {
    opus = ''
      INPUT_FILE_NAME="$1"
      TEMPORARY_FILE_NAME="/tmp/''${1%.*}.opus"
      TARGET_FILE_NAME="''${1%.*}.m4a"

      BITRATE="''${2:-128k}"

      ${ffmpegExe} -i $INPUT_FILE_NAME \
        -b:a $BITRATE \
        -c:a libopus \
        $TEMPORARY_FILE_NAME

      ${ffmpegExe} -i $TEMPORARY_FILE_NAME \
        -map_metadata -1 \
        -fflags +bitexact \
        -flags:v +bitexact \
        -flags:a +bitexact \
        -c:a copy \
        -f mp4 \
        $TARGET_FILE_NAME

      rm $TEMPORARY_FILE_NAME
    '';
  };
in
pkgs.mkShell {
  packages =
    with pkgs;
    [
      ffmpeg
      rsgain
    ]
    ++ (mkAliases aliases);
}