PHP Curl to form this Post Request

Can someone help me in forming this following POST request in PHP CURL ?

As mentioned in this URL : http://ift.tt/1En8lys

 curl -v -X POST --form
 'metadata={"name":"testVideo1","kind":"FILE"}' --form
 'content=@sample_iTunes.mp4'
 'http://ift.tt/1Nl96lB'
 --header "Authorization: Bearer
 Atza|IQEBLjAsAhQ5zx7pKp9PCgCy6T1JkQjHHOEzpwIUQM"

this is what am trying... i want to form the above mentioned type curl request to the amazon server so i can upload a file into it. as there is no examples available am struck in this... can someone helps on this ?

            $fields = array(
                'multipart' => array(
                    'name' => 'testupload',
                    'content' => array(
                        'kind' => 'FILE',
                        'name' => 'hi.jpg',
                        'parents' => $parents
                        )
                )
            );

        $fields_string = json_encode($fields);

        //open connection
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $contenttype);
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_HEADER, 1);
            curl_setopt($ch, CURLOPT_POST, count($fields));
            curl_setopt($ch, CURLOPT_POSTFIELDS, $fields_string);

        $result = curl_exec($ch);  
        $httpstatus = curl_getinfo($ch, CURLINFO_HTTP_CODE);