Node JS/azure functions passing video information back from api call - node.js

Question

So essentially, what my api call does is it 1) takes in video data using parse multipart, 2) converts that video data to a real mp4 file using ffmpeg, and then 3) is supposed to send back the video data to the client in the response body.
Steps 1 and 2 work perfectly - it's that third step that I am stuck on.
The api call creates the Out.mp4 file, but when I try and read its info using createReadStream, the chunks array doesn't populate, and a null context.res body is returned.
Please let me know what I am doing wrong and how I can pass back the video info properly so as to be able to convert the video info back to a playable mp4 file on the client's side.
Also, lmk if you have any questions or things I can clarify.
Here is the api call index.js file
const fs = require("fs");
module.exports=async function(context, req){
try{
//Get the input file setup
context.log("Javascript HTTP trigger function processed a request.");
var bodyBuffer=Buffer.from(req.body);
var boundary=multipart.getBoundary(req.headers['content-type']);
var parts=multipart.Parse(bodyBuffer, boundary);
var temp = "C:/home/site/wwwroot/In.mp4";
fs.writeFileSync(temp, Buffer(parts[0].data));
//Actually execute the ffmpeg script
var execLineBuilder= "C:/home/site/wwwroot/ffmpeg-5.1.2-essentials_build/bin/ffmpeg.exe -i C:/home/site/wwwroot/In.mp4 C:/home/site/wwwroot/Out.mp4"
var execSync = require('child_process').execSync;
//Executing the script
execSync(execLineBuilder)
//EVERYTHING WORKS UP UNTIL HERE (chunks array seems to be empty, even though outputting chunk to a file populates
//That file with data)
//Storing the chunks of the output mp4 into chunks array
execSync.on('exit', ()=>{
chunks = [];
const myPromise = new Promise((resolve, reject) => {
var readStream = fs.createReadStream("C:/home/site/wwwroot/Out.mp4");
readStream.on('data', (chunk)=> {
chunks.push(chunk);
resolve("foo");
});
})
})
myPromise.then(()=>{
context.res={
status:200,
body:chunks
}
})
}catch (e){
context.res={
status:500,
body:e
}
}
}```

Answer 1

you can use an npm package called azure-function-express this package will basically convert your azure function to an express
This way you can directly read the mp3 file you saved and send it directly.
const createHandler = require("azure-function-express").createHandler;
const express = require("express");
const fs = require('fs');
const app = express();
app.get("/api/HttpTrigger1", (req, res) => {
res.writeHead(200, {'Content-Type': 'video/mp4'});
let open = fs.createReadStream('./test.mp3');
res.send(open);
});
This way you will be able to share the video also running the ffmpeg might also be simple