codeigniter + ajax + progressbar

[eluser]codeplay[/eluser]
hello there!

i have this upload form which uploads a video to the server, encodes it (using FFMPEG), and puts it onto Amazon S3.

i have a jquery progressbar which shows the progress of the uploading+encoding process, by using ajax to do a GET request and to update it every 1/2 a second.

im setting the progress variable after each stage of the process.

the problem is it doesnt work as the data that is returned is always 'nothing'.

i just cant see what im doing wrong and whether the technique im using would work.

heres some of my code:

header.php (view)

Code:

function beginUpload() {
    var i = setInterval(function() {
        
        $.get('<?php echo base_url(); ?>upload/progress', function(data) {    
          $( "#uploadprogressbar" ).progressbar( "option", "value", parseInt(data) );
        });

    
     }, 500);
  }

$(document).ready(function(){

    $("#uploadform").submit(function () {
        beginUpload();
    });

     $("#uploadprogressbar").progressbar({value:0});
....

upload.php (controller)

Code:

class Upload extends Controller {

    public $progress;
    
    function Upload()
    {
        parent::Controller();
        $this->load->helper('url');
        $this->load->helper('form');
        $this->load->library('form_validation');
    
        $this->load->model('Video');
    }
    
    function index()
    {    
        $this->processupload();
    }
    

    function processupload()
    {    
                
        $data['page_title'] = "Upload";
        //validation stuff omitted
        
        $this->form_validation->set_error_delimiters('<div class="form_error">', '</div>');
        
        
        if ($this->form_validation->run() == FALSE)
        {
    
            $this->load->view('header', $data);
            $this->load->view('upload');
            $this->load->view('footer');
            
        } else {
            
            $uniq_id = time();
            
            $this->setprogress(10);
            $error = $this->do_upload($uniq_id);
            
            
            if($error == "")
            {
                $this->setprogress(90);
                $video_data = array(
                    'user_id'    => $user_id,
                    'sport_cat' => $this->input->post('sport_cat'),
                    'competition_cat' => $this->input->post('competition_cat'),
                    'title' => $this->input->post('title'),
                    'description' => $this->input->post('description'),
                    'tags' => $this->input->post('tags'),
                    'uniq_id' => $uniq_id
                );
            
            
                $this->Video->add($video_data);  
                
                $this->setprogress(100);
                redirect(base_url());
            } else {
            
                $data['uploaderror'] = '<div class="form_error">'.$error.'</div>';
                
                $this->load->view('header', $data);
                $this->load->view('upload', $data);
                $this->load->view('footer');
                
            }
        }
    }    
    
    function do_upload($uniq_id)
    {
        $config['upload_path'] = 'assets/videos/temp/';
        $config['allowed_types'] = 'wmv';
        $config['max_size']    = '50000';
        $config['file_name'] = $uniq_id.".wmv";
        
        $this->load->library('upload', $config);
    
        
        $error = "";
        $this->setprogress(20);
        if ( ! $this->upload->do_upload('upload_video'))
        {
            $error = $this->upload->display_errors();
            //print_r($config);
        }
        else
        {
            $this->setprogress(30);
            $data = $this->upload->data();
            $this->setprogress(40);
            echo exec("ffmpeg -i "."assets/videos/temp/".$data['file_name']." -ar 22050 -ab 32 -f flv -s 480x360 "."assets/videos/temp/".$data['raw_name'].".flv");
            $this->setprogress(60);
            //include the S3 class
            if (!class_exists('S3'))require_once('S3.php');

            //AWS access info
            if (!defined('awsAccessKey')) define('awsAccessKey', 'xxx');
            if (!defined('awsSecretKey')) define('awsSecretKey', 'xxx');

            //instantiate the class
            $s3 = new S3(awsAccessKey, awsSecretKey);

            
            //move the file
            if (!$s3->putObjectFile("assets/videos/temp/".$data['raw_name'].".flv", "xxx", $data['raw_name'].".flv", S3::ACL_PUBLIC_READ)) {
                $error ="Something went wrong while uploading your file...";
            }
            $this->setprogress(80);
            
        }
        
        return $error;
    }    
    

    
    function setprogress($value)
    {
        $this->progress = $value;
    }
    
    function progress()
    {
        echo $this->progress;
    }

.........

all help and advice will be greately appreciated! thank you