How to add the files content from $FILES to CURL in PHP?

Question

I would like to send file using CURL but so far my attempt has no luck , here is how I create the CURL , it can connect but sent without File

function create_video() {
        $api = "http://api.brightcove.com/services/post";

        try {
            $ch = curl_init();

            if (FALSE === $ch) {
                throw new Exception('failed to initialize');
            }

            $request = 'json={"params":{"video":{"name":"test","shortDescription":"test","startDate":1432282741000,"endDate":null},"encode_to":"MP4","create_multiple_renditions":"True","token":"' . WRITE_TOKEN . '"},"method":"create_video"}';

            curl_setopt($ch, CURLOPT_URL, $api);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
            curl_setopt($ch, CURLOPT_POST, true);
            curl_setopt($ch, CURLOPT_POSTFIELDS, $request);

            $content = curl_exec($ch);

            if (FALSE === $content) {
                throw new Exception(curl_error($ch), curl_errno($ch));
            }

            die(var_dump(json_decode($content)));

            return json_decode($content);
        } catch (Exception $e) {
            trigger_error(sprintf('Curl failed with error #%d: %s', $e->getCode(), $e->getMessage()), E_USER_ERROR);
        }
    }

It return the error code create_video requires a filestream or remote asset references from the server. The problem is how to modify the code to add file to the CURL, assuming I have several files in the $FILES already.

Expected Request Payload (From Chrome Console)

------WebKitFormBoundaryCAB6WEANBJxoB3Op
Content-Disposition: form-data; name="JSONRPC"

{"params":{"video":{"name":"test","shortDescription":"test","startDate":1432282741000,"endDate":null},"encode_to":"MP4","create_multiple_renditions":"True","token":"VyocgALDnxU8HPvmnSnckgmXjoPlYWomc2La5Tn-evuAfsnSPJJoow.."},"method":"create_video"}
------WebKitFormBoundaryCAB6WEANBJxoB3Op
Content-Disposition: form-data; name="filePath"; filename="big_buck_bunny.mp4"
Content-Type: video/mp4


------WebKitFormBoundaryCAB6WEANBJxoB3Op
Content-Disposition: form-data; name="JSONView"

{"params":{"video":{"name":"test","shortDescription":"test","startDate":1432282741000,"endDate":null},"encode_to":"MP4","create_multiple_renditions":"True","token":"VyocgALDnxU8HPvmnSnckgmXjoPlYWomc2La5Tn-evuAfsnSPJJoow.."},"method":"create_video"}
------WebKitFormBoundaryCAB6WEANBJxoB3Op--

Thanks a lot.