Fluent-ffmpeg won't create video file sometime it will create? - node.js

Question

anyone know the reason of this problem? what is the issue?
in this code, i am trying to convert a blob into video format. but sometime it is working and sometime not. can anyone help me in this?
const recordVideo = require('../model/recordVideo_model')
const { join, dirname } = require('path');
const { fileURLToPath } = require('url')
const { mkdir, open, unlink, writeFile } = require('fs/promises');
const {Blob, Buffer} = require('buffer');
const { path } = require('#ffmpeg-installer/ffmpeg');
const ffmpeg = require('fluent-ffmpeg');
ffmpeg.setFfmpegPath(path)
// const __dirname = dirname(fileURLToPath(import.meta.url));
const saveData = async(data, roomid, course_id)=>{
//console.log(data);
const videoPath = join(__dirname, '../video');
//final folder name
//const dirName = new Date().toLocaleDateString().replace(/\./g, '_');
const dirName = roomid;
// console.log(`dirName: ${dirName}`);
//const dirPath = `${videoPath}/${dirName}`;
const dirPath = `./public/video/canvideo/${dirName}`;
const fileName= `${Date.now()}-${roomid}.webm`;
//const fileName= `${roomid}.webm`;
const tempFilePath = `${dirPath}/temp-${fileName}`;
const finalFilePath = `${dirPath}/${fileName}`;
let fileHandle;
try {
fileHandle = await open(dirPath);
console.log(`open the file${fileHandle}`)
}
catch {
await mkdir(dirPath);
console.log(`making directory${fileHandle}`)
}
finally {
if (fileHandle) {
fileHandle.close();
console.log(`closing ${fileHandle}`)
}
}
try {
const videoBlob = new Blob(data, {
type: 'video/webm'
})
const videoBuffer = Buffer.from(await videoBlob.arrayBuffer())
const res = await recordVideo.findOne({roomid:roomid, recordType:'canvas'})
if(!res){
await writeFile(tempFilePath, videoBuffer)
await ffmpeg(tempFilePath)
.outputOptions([
'-c:v libvpx-vp9',
'-c:a copy',
'-crf 35',
'-b:v 0',
'-vf scale=1280:720','-max_muxing_queue_size 1024'
])
.on('end', async () => {
await unlink(tempFilePath)
console.log(`*** File ${fileName} created`)
//insert database entry (recorded video entry with same details roomid, finename, finalfilepath, created at)
await recordVideo.create({roomid:roomid,filename:fileName,filePath:finalFilePath,recordType:'canvas', courseid:course_id});
}).on('error', function(err) {
console.log('An error occurred: ' + err.message);
})
.save(finalFilePath, dirPath);
}
}
catch (e) {
console.log('*** Erro in code ', e)
}
}
module.exports = {saveData,};
if any help me in this. it would be great for me.
in this code, i am trying to convert a blob into video format. but sometime it is working and sometime not. can anyone help me in this?