Question about CD/DVD Speed and Benq Drives

vbimport

#1

I have two questions about the CD/DVD Speed Quality test that I’ve been wondering about since I got my new 1640 the other day.

I have noticed with my 1640 that no matter what read speed I specifiy for the quality test, the drive starts out slow and ramps up, like from 4x at start to 8x at finish. When I checked many of the posted resutls for media tested with other folks drives I see the same trend, even if they have maximum set as the speed. My Lite-On 1693 will stay at whatever speed I specify, so if it starts at 4x, it’s 4x all the way thru.

Is this normal? Does having a fixed vs variable speed affect the results in any adverse ways? Or give some advantage?

I have also noticed that scanning the same disc in the Lite-On 1693 will give a different quality result than in the Benq 1640, even if the number of errors is roughly the same. Lets say you are 10% of the way through a scan, and there have been 20 PIFs, and the PIEs are very close to the same, the Lite-On will always be a lower score. Is this because it does not report Jitter?

What affect does Jitter (or the lack of it reporting) play in the assessment of quality with this program?

Thanks,
Chuck


#2

I can’t recall the exact technical specifics but Lite-On and BenQ use different methods to scan discs and are not directly comparable, maybe someone else can fill in the details.

4x is normal for Lite-On but 8x is normal for BenQ’s method, in Nero CD/DVD Speed when set to maximum the read speed is by default 8x, it is not recommended to scan at a higher speed.

As for jitter I think with BenQ drives it should generally not exceed 12% for the best result so obviously lower is better, how this affects other drives I cannot say as I do not know but the DVD spec says a jitter of 9% is the standard though many drives can reads discs that are not in line with certain standards.


#3

Thanks, I assumed it was some mechanical difference in the drives, but wasn’t sure. I had seen that folks tended to use different scan speeds for the various brands, 4x for Lite-On and 8x for Benq. I just found it interesting that no matter what speed is set on the Benq it reads at a variable rate, starting slow and ramping up. Is the Benq not able to maintain a set speed?And I was interested in why a disc with the same number of errors, regardless of how it was scanned, would show a lower quality score on one, presumably because it couldn’t determine the Jitter. I guess maybe I could turn off Jitter on the Benq and see how it reports quality then.

In any case, I’m way happy with my 1640. Nice burns. But then I was also way happy with the Lite-On 1693. Now I just have way too many options for having fun burning.

:slight_smile: