How to use the fluent-ffmpeg.getAvailableFilters function in fluent-ffmpeg

async (req, res, next) => {
    try {
      const promisify = (fn) =>
        new Promise((resolve, reject) =>
          fn((err, data) => err ? reject(err) : resolve(data)));

      const [
        formats, codecs, encoders, filters, postcount, boardcount, spaceused
        ] = await Promise.all([
          promisify(ffmpeg.getAvailableFormats),
          promisify(ffmpeg.getAvailableCodecs),
          promisify(ffmpeg.getAvailableEncoders),
          promisify(ffmpeg.getAvailableFilters),
          Post.estimatedDocumentCount(),
          Board.estimatedDocumentCount(),
          new Promise((resolve, reject) => {
            du(config.html_path, (err, size) => {
              if (err) {
                reject(err);
                return;
              }
              resolve(size);
            });
          }),
        ]);

      const ffmpegPath = process.env.FFMPEG_PATH;
      const ffprobePath = process.env.FFPROBE_PATH;
      const ffmpegData = {formats, codecs, encoders, filters, ffmpegPath, ffprobePath};

return new Promise(function(resolve, reject) {

            if (!_self.options.normalizeLevel || _self.options.normalizeLevel < 3) {
                return resolve();
            }

            let availableFilters;

            ffmpeg.getAvailableFilters(function(err, filters) {
                availableFilters = filters;
                normalize();
            });

            function normalize() {

                _self.stages[_self.currentStageNum].command = new ffmpeg(_self.path, {
                        logger: _self.encoder.logger
                    }).inputOptions('-hide_banner').format('null').output('-')
                    .on('start', function(commandLine) {
                        if (_self.paused)
                            _self.pause();
                        _self.encoder.logger.debug('Running Query:', commandLine);
                    })
                    .on('error', function(err, stdout, stderr) {
                        _self.encoder.logger.debug(err.stack);