Need to use HTTPService rather than URLRequest to send data. content type is messing with the data?

I need to send a byte 开发者_JAVA技巧array of data (its an image source) along with a bunch of other vars to a service. If I send the byte array using something like the following

var request:URLRequest = new URLRequest ( 'http://www.mydomain.com/upload.php' );
            var loader: URLLoader = new URLLoader();
            request.contentType = 'application/octet-stream';
            request.method = URLRequestMethod.POST;
            request.data = byteArrayOfImage;
            loader.load( request );

and in the php

$fp = fopen( 'myImage.jpg', 'wb' );
fwrite( $fp, $GLOBALS[ 'HTTP_RAW_POST_DATA' ] );
fclose( $fp );

then this saves the image fine. But I need to send extra vars down so I'm trying to use the following.

var service : HTTPService = new HTTPService();
service.method = "POST";
service.contentType = 'application/x-www-form-urlencoded';  
service.url = 'http://www.mydomain.com/upload.php';         
var variables : URLVariables = new URLVariables();      
variables.imageArray = myImageByteArray;
variables.variable2 = "some text string";
variables.variable3 = "some more text";             
service.send( variables );

Then in the php

$byteArray= $_REQUEST["imageArray"];
$fp = fopen( 'myImage.jpg', 'wb' );
fwrite( $fp, $byteArray );
fclose( $fp );

But this isn't working. The file sizes of the saved files are different and the later doesn't save it as an image. What am I missing. Is it that the working content type is application/octet-stream and the content type of the one that doesn't work is application/x-www-form-urlencoded?

I've found a similar question which gives a workaround. Not ideal, but it works.

http://www.google.es/search?sourceid=chrome&ie=UTF-8&q=as3+base64+encoder

http://code.google.com/p/jpauclair-blog/source/browse/trunk/Experiment/Base64/src/Base64.as

So what I've done is the following using the Base64 code.

var encodedString : String = Base64.encode( imageByteArray );
var service : HTTPService = new HTTPService();
service.method = "POST";
service.contentType = 'application/x-www-form-urlencoded';  
service.url = 'http://www.mydomain.com/upload.php';         
var variables : URLVariables = new URLVariables();      
variables.imageArray = encodedString;
variables.variable2 = "some text string";
variables.variable3 = "some more text";             
service.send( variables );

then in the php side

$byteArray= $_REQUEST["imageArray"];
$byteArray= base64_decode($byteArray);
$fp = fopen( 'myImage.jpg', 'wb' );
fwrite( $fp, $byteArray);
fclose( $fp );

This saves a valid jpg image. Not ideal but it works, I'd still like a solution that doesn't involve encoding the byte array. So feel free to answer even though I've found this workaround.