Error: Input format lavfi is not available

import { default as ffmpeg, default as ffprobe } from "fluent-ffmpeg";
const command = ffmpeg();
command.input("anullsrc=channel_layout=mono:sample_rate=44100");
command.inputFormat("lavfi");
command.addOption("-t", "20");
command.output("test.mp4")
command.run();

Error: Input format lavfi is not available

// TypeScript
const bypass = (command: ffmpeg.FfmpegCommand) => {
    const bk = command.availableFormats;
    command.availableFormats = (cb: (err: any, data: any) => void) => {
      bk.bind(command)((err, data) => {
        const lavfi = {
          canDemux: true,
          canMux: true,
          description: "Lavfi",
        };
        cb(err, { ...data, lavfi });
      });
    };
  }