converting using ffmpeg in background [duplicate]

Possible Duplicate:

Asynchronous shell exec in PHP

i'm witing a php script which convert video into FLV.when the converting is in progress the user has to wait for completion of converting but What I want to do is when the converting is in process开发者_高级运维 the script continue the next lines after shell_exec .How should I do that?

Thanks

As Jared said, try looking at Asynchronous shell exec in PHP