Optimal scanning speed on benQ 1625

vbimport

#1

the optimal scanning speed on the 1625 is 8x; is this for both cd and dvd? i’m using cd-dvd speed and now i also have the 8x CLV option, what exactly does it do?


#2

For CDs, I don’t know that there’s really any ‘standard’, though I’d suggest either maximum or something like 32x. 8x CLV is, 8x CLV. Constant Linear Velocity, CLV maintains the same speed throughout the entire read/write. Normally it’d be CAV, Constant Angular Velocity, which means it starts out at a slower speed and gradually increases to 8x at the edge of the disc. Therefore CLV is going to be quicker since it maintains the same speed throughout. Is it actually 8x CLV, or 8x P-CAV, as none of my Benqs actually have the option of 8x CLV? In any event, 8x CAV (or just ‘8x’) is the most commonly used scanning speed for Benqs, it’s considered the ‘standard’ for the CDFreaks forum. Other speeds aren’t any less valid or useful though, so for your own personal uses trying out other speeds is fine, though posting 8x CAV makes for the most useful comparisons with scans from other users since it’s the ‘standard’.


#3

its pretty crazy, i went from a drive with no scanning capability at all (tests stopped a few seconds in with any media on the hp640c), to a drive with seemingly perfect scanning (benQ1625). i dont think my NEC even knows what jitter is…

anyway my options seem sort of random, and no there isn’t a 8x p-cav…

8x
8x CLV
12x
12x CLV
16x CLV
24x
24x P-CAV
32x
32x P-CAV
40x
48x
Max

strange mix of options… anyhow im still trying to find a batch of CMC’s that aren’t crap, so far HP are the only ones. TDK is doing OK, still testing tho. im finding it really hard to correlate scanning results with actual playback… running this stuff on my 10 year old APEX dvd player and an equally old dell laptop drive that has never been upgraded i find that even the worst staples brand cmc’s burned at max and showed a 0 QS typically played all the way through without any pauses or skipping while Sony DVD+R’s with near perfect scanned quality (~96) sometimes stop playing halfway.
bah, i dont know whats going on.


#4

Ok, so those are the speeds listed when you have a CD inserted, not a DVD. I’ve always had good results with CMC, though their 16x +R discs are quite variable in quality - for 16x CMC I would suggest buying their -R discs as they’re much more consistent. 8x and slower both +R and -R are fine. And for the 16x discs I’d suggest that you burn at 8x or 12x, not 16x. I burn almost all of my 16x media at 8x, occasionally 12x. I’ve had decent results with Sony, nothing spectacular but I’ve had no problems with them. And again, for scanning DVDs I’d suggest 8x as a good starting point.


#5

For CD scanning, use advanced disc test & set scan speed to 16x CLV. This will give you acceptable scan time with speed which will not adversely affect Jitter reading.


#6

what IS a good range for jitter? i know the flatter the better, and variations of ~2% are ok, but what is an acceptable average jitter? i get about 8~9%…


#7

How long is a piece of string? That’s a difficult question to answer.

12% jitter (except random peaks) is not acceptable IMO.

7% is pretty much the lowest you can possibly get.

So the right answer is somewhere in there, and it depends on the scanning drive because drives can show different jitter levels for the same disc, it depends on scanning speed because reported jitter tends to be higher at higher scanning speeds (but not always), and it can even vary 1-1½% from scan to scan in the same drive at the same speed.