Automatically renicing a process

[SL]

Hello

I didn't get any match on monit+renice, neither on the mailing list nor 
on the web. And yet, I think I have a pretty basic use case, so I might 
be missing something totally obvious.

I would like to automatically renice a process after it starts.

I have a NAS in charge of transcoding a webradio in realtime and 
streaming it to my LAN. Whenever another CPU-intensive is launched, the 
streaming starts skipping. Increasing the priority of the transcoding by 
hand prevents the skipping.

The transcoding server starts with a /etc/init.d script that uses 
start-stop-daemon. start-stop-daemon lets you define the nice level, but 
it would require editing the Debian packaged script, which I would like 
to avoid.

How would you do that?

Thanks
--
Sylvain