addCoverImage({ video, output, cover }) {
    return new Promise((resolve, reject) => {
      const command = this.createCommand();
      command.addInput(video);
      command.addInput(cover);
      command.output(output);
      command.outputOptions(
        '-map 0 -map 1 -c copy -c:v:1 png -disposition:v:1 attached_pic'.split(' '),
      );
      //command.on('start', commandLine => console.log(commandLine));
      command.on('end', () => {
        resolve();
        this.destroy(command);
      });
      command.on('error', (error, stdout, stderr) => {
        reject([error, stdout, stderr]);
        this.destroy(command);
      });
      command.run();
    });
  }
Set a cover thumbnail for the video
@public