Convert a file using FFMPEG and upload to AWS S3 Nodejs - node.js

Question

Hey everyone so quick question I want to allow a user to upload a WebM file and convert it using FFmpeg to mp4. I am using Nodejs for the backend and already have a route that uploads files to Amazon S3 file storage. But let's say I wanted to send that file and not store it anywhere but convert it to mp4 from the request itself is that possible? If not is it possible to take an s3 file URL and convert it to mp4? Can anybody point me in the right direction as to what is possible and the best way to do this?
basically all I want to do is
const objectUrl = createObjectURL(Blob);
ffmpeg -i objectURL S3OutputLocation
or
ffmpeg -i myS3InputLocation myS3OutputLocation

Answer 1

Okay so there is a couple of things you have to do in order to make this work.
1. you need to set up a local instance of multer as you need to upload the file locally before going to s3. I tried to do it with s3 directly but it seemed to use a lot of costly and time-consuming read operations that took much longer than writing the file to the server first. I found this to be the best solution.
You do this like so:
const localStorage = multer.diskStorage({
destination: function(req, file, cb) {
const destination = __dirname + "\\canvas-uploads";
console.log("destination", destination);
cb(null, destination);
},
filename: function(req, file, cb) {
const filename = req.body.id + "." + file.mimetype.toString().slice(file.mimetype.toString().lastIndexOf("/") + 1);
console.log("filename", filename);
cb(null, filename);
}
});
const uploadLocal = multer({
storage: localStorage
});
You need to set up ffmpeg-fluent and wrap it in a promise so you can be sure it's finished with all your processing (uploading to s3 and etc in the same route.) for convenience.
you do this like so:
router.post('/upload-temp', uploadLocal.array("upload"), async(req, res, next) =>{
res.json({id: req.body.id});
});
router.post('/ffmpeg', async(req, res, next) => {
try {
const reqPath = path.join(__dirname, '../upload/canvas-uploads/');
const {id, type} = req.body;
const localFileInput = `${reqPath}${id}.webm`;
const localFileOutput = `${reqPath}${id}.${type}`;
console.log("localInput", localFileInput);
console.log("localOutput", localFileOutput);
const key = `canvas/${id}.${type}`;
await new Promise((resolve, reject) => {
ffmpeg().input(localFileInput)
.withOutputFormat(type)
.output(localFileOutput)
.on('end',async ()=> {
const fileContent = await fs.readFileSync(localFileOutput);
await fs.unlinkSync(localFileInput);
await fs.unlinkSync(localFileOutput);
const params = {
Bucket: process.env.BUCKET_NAME,
Key: key,
Body: fileContent
}
await s3.putObject(params).promise();
resolve();
}).run();
})
res.send("success")
} catch(error){
console.log(error);
res.send(error);
}
});