I'm setting up an Express.js endpoint that would support decoding a base64 string that came from the client (camera record), which is basically an encoded webm video. The problem is that to validate this, I am trying to create a .webm video file from the encoded base64 string on the server. Unfortunately this results in a video file that cannot be played due to an error of "No video with supported format and MIME type found" (Ubuntu 18.04). I did not have any issue with any other .webm files but also the base64 URL is sure to be correct as I am using it on the cliet as the source of a element to replay what was recorded and works fine. The issue I suspect is something wrong with the code that generates the file on the server route.

import express from "express";
import multer from "multer";
import fs from "fs";
const router = express.Router();
// ...

router.post("/upload", multer().fields([]), (req, res) => {
  const formData = req.body;
  // formData.vid_string is the base64 encoded string
    Buffer.from(formData.vid_string.split(",")[1], "base64")


I have also tried to change fs.writeFileSync code and add "base64" as a third argument but it has the same result. Any input would be appreciated! Thanks!

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