Real time video recording

I have successfully being able to record video from angular and sent it back to my back-end java application. let me explain the main goal , we need real time video recording , i mean i dont need need to save the whole video at same time then sent it to the back-end , i need real time analyse , so every like 2-3sec i need to send it until it ends u understand please?
here is my code working recording code:

mediaRecorder.onstop = (ev)=>{    
        let blob = new Blob(chunks, { 'type' : 'video/mp4;' });
        chunks = [];
        let videoURL = window.URL.createObjectURL(blob);
        vidSave.src = videoURL;  
         var file = new File([blob], 'video.mp4', {
             type: 'video/mp4'
        // my attempt to send this blob //
        let req = new XMLHttpRequest();
        let formData = new FormData();
        formData.append("file", blob);                               "POST", 'http://localhost:8081/avi/upload-file');

my back end java :

@RequestMapping(value = "/upload-file", method = RequestMethod.POST)
    public void getUploadFile(@RequestParam("file") MultipartFile file) throws IllegalStateException, IOException {
        Path filepath = Paths.get(file.getOriginalFilename());
        File f = new File(file.getOriginalFilename());
        try (OutputStream os = Files.newOutputStream(filepath)) {

How can i send bit by bit this video while its recording? so i can analyse it in the back every 2-3sec