flash.media.Sound not sending HTTP request headers

I am using Flex 3 (ActionScript 3.0). I use the HTTP progressive download to play sound files. I want to secure the sound files, by only serving them when the request comes from my flex app. I chose the simplest solution of adding a HTTP header to each request send from the app. But flash.media.Sound object ignores the he开发者_StackOverflow中文版aders set in flash.net.URLRequest. Here's an example,

URLRequest sndFile = new URLRequest("http://blah.com/media/load_sound.php");
sndFile.requestHeaders = new Array(new URLRequestHeader("req-orgin", "myflexapp"));
Sound snd = new Sound(sndFile);
snd.play();

The value of req-origin comes as null in load_sound.php. When i inspect the request using Firebug, the request headers to http://blah.com/media/load_sound.php doesn't contain the header.

Does anybody know why the header is ignored? Is there any other way to identify that the request came from my flex app?

Thanks

The Flash player has really restricted header support for security reasons. I believe custom headers are only support on POST requests. There are all kinds of restrictions.

You can see additional info here: http://kb2.adobe.com/cps/403/kb403030.html

And here: http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/flash/net/URLRequestHeader.html

A cross domain policy file should solve any issues though, look here:

http://kb2.adobe.com/cps/403/kb403184.html

Goodluck! (You might need it)