anchor.diff:            bucfile:remove_recursive(SpritesPath),
             {error, In, OutName, output_vtt_error}
         end;
  -    {{ok, _}, Error} ->
  -      error_logger:error_msg("Failed to retrieve video duration when generating thumbnails: ~p", [Error]),
  -      bucfile:remove_recursive(SpritesPath),
  -      {error, In, OutName, source_duration_unavailable};
  -    {Error, _} ->
  +    Error ->
         error_logger:error_msg("Failed to retrieve sprite infos when generating thumbnails: ~p", [Error]),
         bucfile:remove_recursive(SpritesPath),
         {error, In, OutName, sprite_creation_error}
  
positive.code: get_stages_number(_) -> 1.
  
  % @hidden
  thumbnails_finalize({ok, In, _Out}, {Movie, OutName, Options, FunOrPid, CmdOptions}) ->
    Every = buclists:keyfind(every, 1, Options, 1),
    OutPath = buclists:keyfind(out_path, 1, Options, "."),
    AssetsPath = buclists:keyfind(assets_path, 1, Options, ""),
  
negative.code:   SpritesPath = filename:join(OutPath, OutName),
    AllSprites = filename:join(SpritesPath, "*.png"),
    [F|_] = Sprites = filelib:wildcard(bucs:to_string(AllSprites)),
    Response = case vice:infos(F) of
      {ok, #{page_width := Width,
              page_height := Height,
              page_x_offset := X,
              page_y_offset := Y}} ->
        {Lines, Columns} = vice_utils:tile(length(Sprites)),
        case generate_vtt(OutName, OutPath, Sprites, AssetsPath, Every, Duration, Lines, Columns, Width, Height, X, Y, Sprite, CmdOptions) of
          {ok, VttFile} ->
  