Question about CD/DVD Speed and Benq Drives



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?



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.


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.