Fluctuating Writing Speed

For some reason, with Herbies 1.07 beta 5 for my NEC 2510a I can only write DVDs at an average of 6x. They start off at 4x, then about a third into the disc go to 6x, then the last third burns at 8x. I want it to burn in 8 minutes as it should, this way takes at least 10.

Anyone else have this problem? I am using Datasafe Ritek G05 DVD-R media with CopyToDVD version 3.

Thats because your DVD-Writer uses the Z-CLV write strategy so it writes in zones ie a certain amount is recorded at 4x, then 6x then finally 8x.

Do you get any buffer underuns while burning?

You should also take into account the Lead-in and Lead-out times.

explain this Z-CLV write strategy please as im not familar with it and the alternatives, can i change it?

also, how can i check if there are any underruns?

You can’t change the write strategy, its how your burner works.

Z-CLV: Zone-Constant Linear Velocity
The disc is divided into zones. After each zone the write speed is increased (note that the Z-CLV mode is not used when reading a disc).

As for buffer-underuns, when burning something see if the green light of your burner goes on and off, if it stays on during the whole burn then you didn’t get a buffer-underun.

I’m not familiar with Copy-To-DVD but it should show whether the write buffer is full or emtpy in %.

4x -> 6x -> 8x change is fine. It is supposed to do so.
I remember 8x(in fact 4x->6x->8x) burning takes a little bit less than 10 min.
If your burning really takes more than 10 min, check the burning speed information
if there’s anything weird happening.

It should start at very low speed, like 0.5x, and then in a few second you have to observe 4x, then it goes to 6x (at the transition you may see something like 3x or 5x, but don’t worry, it should disappear in a few second), then 8x transition happens. At the last stage, there’s an additional step of leadout(or whatever the right term) that takes about 10 sec. Then the burning is over. So, unless you see some weird behavior (for example burning speed drops to 4x permanently at the end of a disc) apart from this, everything is fine.

As jk736 said, a burning time of 10 minutes is OK @8x with NEC drives.

My burns on the NEC take anywhere between 9min15sec and 9min35sec at 8x Z-CLV. And for those who don’t know, NEC uses a very conservative Z-CLV write strategy, changing to 6x and 8x very late in the burn compared to most other drives. This is presumably to keep the drive’s rotation speed down and therefore keep the drive as quiet and as vibration-free as possible.


Nec Z-clv. 0-09gb 4x / 0.9gb-2.2gb 6x / 2.2gb-4.38 8x.

might want to peak at the review and you will see everything about the drive… except the wonderfull herrie firmwares :wink: