Download speed limit

Hello! For my application I need to limit the speed that my application sends data, in my case a binary file. I need to send the speed as a parameter, like: sendfile.php?speed=20000 Would send the file at 20kb/s (forgetting about real byte counts for this example). To send the file, I am doing: $fp=fopen($this->contentfile,"rb"); while(!feof($fp)){ print(fread($fp,1024*8)); flush(); ob_flush(); } fclose($fp); If after ob_flush I do a sleep(), I can limit the speed, but I would like to limit at the speed of the parameter. Is there a way to do this? Thanks, Rangel