Upload large file with Flash/PHP

I 开发者_如何学Goam uploading from desktop big files (up to 200M) to a server using flash's File- which extends FileReference. I'm using PHP on the bakcend.

I have it working, thou the problem I'm facing is that the flash UI freezes during the process and it's hard to think that the users wont freak out and quit the app thinking that it is not working when it is.

I guess the issue is that the whole file goes into memory for the upload. Is there a progressive alternative to using FileReference.upload() and URLRequest?

Ideally, something like URLStream, which I don't think it provides an upload method...