Are DVD-/+R drive speeds real or "max"?

[B S D]

HI,

I checked:
http://www.dvddemystified.com/dvdfaq.html

... but was unable to find a clear answer.

Are drives rated at their full speed for the whole disc, or just at the outer edges?

Thanks,

David

 

[otispunkmeyer]

i am wondering this too...........ive watched nero burn roughly 4000mb to a dvd-r disc and my NEC2510A can burn at 8x on this media, the idsic i used was also 8x

it starts off real slow....but when it gets around 50% it seems to take off!! it completes the 2nd half od the burm much faster than the first....but iam still skeptical as to wether my drive is actually doin what it says it is.

my old liteon 4 speed dvd writer drive which is running on one leg (all CD functionalllity simply packed up) seemd to write 4 speed all the way across the disc, and seems to write faster!


any more info on this would be good

 

[ViRGE]

If you look up CAV, CLV, and Z-CLV, you'll understand what's going on. Basically, if the drive wanted to burn at the same constant speed, it would have to consistently change the rotational speed, since the drive "sweeps" through more data on the outside than the inside due to how the disc is designed(the bits are packed at the same density everywhere, so there are more bits in a sweep the farther out you go). But if we did it this way, we would run in to issues with the physical disc, where it would blow apart if spun too fast; so we either would have to slow down the whole drive so it writes at around 4x consistently(since the outside would match the inside, and 4x is about as fast as you can go inside), or run the drive at the same rotational speed consistently, and live with the fact that more data can be written in a sweep on the outside than the inside, and we hit our maximum speeds on the outside as a result.

In short: the max speed is just the outer edges

PS otispunkmeyer, your 8x drive is probably CAV(constant rotational speed), so it would be really slow on the inside of the disc, as the older CLV drive would run that part at a higher speed

 

[otispunkmeyer]

thanks virge........i assume CAV = constant angular velocity
and CLV = constant Linear velocity?

 

[B S D]

So, is it safe to say that current DVD writters are Zoned-CLV?

 

[ViRGE]

Originally posted by: B S D
So, is it safe to say that current DVD writters are Zoned-CLV?

Most seem to be, but Sony's DRU-540A is PCAV for DVD+R's and CD's.

 

[Arcanedeath]

Depends on the drive but most are Z CLV for DVD burning and CD burning but it totaly depends on your model drive as various drives support all the methods except stright CAV

 

[Belzer]

You can check Videphelp's list to see what a specific DVD writer uses of CAV, CLV, PCAV or ZCLV for its max speed in the different formats.