when i burn dvd-r/rw with my dvdr16k (dvdr1640p) philips velocity is 0.5x.
in windows there aren't problems.
i have installed debian sid
kernel 2.6.11.8-vanilla (compiled by me);
the problem appears also if i burn dvd with k3b/growisofs.
with dvd+r/rw i don't have problem.
i try with dvd-rw (verbatim 2x) and dvd+rw (verbatim 4x).

in windows to burn a 1,3 GB file i spend 7,30 minutes in linux with nero (k3b) 40 minutes.

i have dma enabled and, i repeat, with dvd+rw i haven't problem.

someone can help me???????????

ciao
Luigi

If the problem does not occur with Windows, but only under Linux, with both NeroLINUX and k3b, then I would suspect a kernel problem.
Have you anther kernel that is installed on your machine ?

I encountered a velocity problem myself about two weeks ago. After upgrading to KDE 3.4 on my Gentoo PC burning speed was always around 1x-speed.

The problem was a removable-media-daemon in KDE. This little "bastard" caused the burn process to interrupt about every 2-3 seconds (polling of drives I suppose). Turning in off through kcontrol -> KDE Components -> Service Manager -> KDED Media Manager solved my personal burn speed problem.

Nice to know ! I will check and maybe add it inside the "bad process" list...