Cloud functions for Firebase: killing long processes without touching maximum timeout

I need to transcode videos from webm to mp4 when they are uploaded to firebase storage. I have a demo of the code that works , but if the uploaded video is too large, the firebase functions will disconnect me until the conversion is complete.I know it is possible to increase the timeout limit for the function, but it seems like a mess as I cannot confirm. that the process will take less time than the timeout limit.

Is there a way to stop firebase from timed out without increasing the maximum timeout limit?

If not, is there a way to complete time-consuming processes (like converting video), but still triggering each process using firebase function triggers?

Even if doing time consuming processes using firebase functions is not something that really exists, is there a way to speed up the fluent-ffmpeg conversion without touching its quality? (I understand this part is a lot to ask. I plan on lowering the quality if absolutely necessary, as the reason webpages are converted to mp4 is related to IOS devices)

For reference, here's the bulk of the demo I mentioned. As I said, the complete code can be here , but this section of code, copied over, is the part that creates the Promise, making sure the transcoding is complete. The complete code is only 70 lines, so it should be relatively easy to go through if needed.

const functions = require('firebase-functions');
const mkdirp = require('mkdirp-promise');
const gcs = require('@google-cloud/storage')();
const Promise = require('bluebird');
const ffmpeg = require('fluent-ffmpeg');
const ffmpeg_static = require('ffmpeg-static');

      

        
        
        
      

    

(There is a bunch of text parsing code here and then the next piece of code inside the onChange event)

function promisifyCommand (command) {
    return new Promise( (cb) => {
        command
        .on( 'end',   ()      => { cb(null)  } )
        .on( 'error', (error) => { cb(error) } )
        .run();
    })
}
return mkdirp(tempLocalDir).then(() => {
    console.log('Directory Created')
    //Download item from bucket
    const bucket = gcs.bucket(object.bucket);
    return bucket.file(filePath).download({destination: tempLocalFile}).then(() => {
      console.log('file downloaded to convert. Location:', tempLocalFile)
      cmd = ffmpeg({source:tempLocalFile})
               .setFfmpegPath(ffmpeg_static.path)
               .inputFormat(fileExtension)
               .output(tempLocalMP4File)
      cmd = promisifyCommand(cmd)
      return cmd.then(() => {
        //Getting here takes forever, because video transcoding takes forever!
        console.log('mp4 created at ', tempLocalMP4File)
        return bucket.upload(tempLocalMP4File, {
            destination: MP4FilePath
        }).then(() => {
          console.log('mp4 uploaded at', filePath);
        });
      })
    });
  });