Output Buffering/Register Shutdown Function

[matthewjumpsoffbuildings]

Hi, Im using PHP 4.4 in a CMS. I have an ob_start() and a function

function endBuffer(){

	$buffer = ob_get_contents();
	ob_end_clean();

	$buffer = displayBuffer($buffer);

	echo $buffer;

}

Initially I was just doing ob_start('displayBuffer'); but i learnt i cant use output buffers in the ob_start callback (displayBuffer).

 

So, I put everything in endBuffer and tried to call that using register_shutdown_function(endBuffer) but it looks like, on shutdown, the buffer is already flushed?

 

How can I set this up so that the endBuffer function gets called at the end of the script, but before it automatically gets flushed?