video – ffmpeg get frame as a buffer

Used fluent-ffmpeg library

const ffmpeg = require(‘fluent-ffmpeg’);
const ffmCmd = ffmpeg();

ffmCmd.input(videoStream).outputOptions([
    "-vf select="gt(scene\,0.4)"",
    "-vsync vfr"
]).saveToFile('frame-%06d.png');

Instead of saving as image file how can I get as a array of buffer or base64 of frame ? Please help not so good with this library.

Instead of saving as image file how can I get as a array of buffer or base64 of frame ? Please help not so good with this library.