async function ffmpeg(downloadUrl, version, platform, arch, cacheDir) {

  /**
   * URL to download specific FFmpeg binary from.
   * @type {string}
   */
  const url = [
    downloadUrl,
    version,
    `${version}-${platform}-${arch}.zip`,
  ].join('/');

  /**
   * Absolute path of compressed file which contains FFmpeg binary.
   */
  const ffmpegFileAbs = path.resolve(
    cacheDir,
    `ffmpeg-${version}-${platform}-${arch}.zip`,
  );
  await request(url, ffmpegFileAbs);

  return ffmpegFileAbs;
}
Download community FFmpeg binary from `https://github.com/nwjs-ffmpeg-prebuilt/nwjs-ffmpeg-prebuilt`.
@param  {string}          downloadUrl  - Download server
@param  {string}          version      - Runtime version
@param  {string}          platform     - NW supported platform
@param  {string}          arch         - NW supported architecture
@param  {string}          cacheDir     - Directory to store FFmpeg binary
@returns {Promise<string>}              Path of compressed file which containscommunity FFmpeg binary.