Which Drive Do I Trust?

I always knew that for a fact

(Actually i know nothing and that's all i know..... or something)

Not quite, the drive is still an important variable in the equation since its the one doing the reading. A different drive would read differently leading me to believe the quality scan results are a combination of several factors.

No, as "errors" as referred to here are a result of the reading process. That errors would be counted and reported before or after the correction stage doesn't change this fact in the least.

Actually that errors would actually be reported "before" or "after" correction makes no difference whatsoever, what is reported in all cases are the errors before correction (even if they are reported after the correction stage... see my point? - think of PIF...), or all this would make no sense at all: unless they reach their absolute limits (for the drive's ability) leading to a POF, all PIE/PIF errors can be corrected, so there would be nothing in the scans (at least most of the time..) if the errors reported were errors after correction!

And once more to be sure that the point is noticed: PIE/PIF errors reported are a result of the reading process.

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Last edited by Wizzu; 06-05-2006 at 03:30.

Any scan is a combination of several factors. When testing you try to keep the same conditions and compare results. When you have done this many times you may get an idea of how things work. Here we have many ideas bc ppl have different setups but imo if you compare everything in the forums mainpage and other related sites you may be able to see through personal setups and i find it safe to say that some combinations of drive & media is much preferable than others both regarding scanning/testing and writing/reading compatibility.

You can put 1000s of questions to any theory and it's fine but just bc you have qualified doubt it doesn't mean the theory is bad (or good). Experience will let you know. If you don't learn and improve through experience you get pretty much nowhere

Discussion continued from this thread over in the LiteOn forum, with the most relevant posts starting here. The discussion is about comparing jitter scans performed on LiteOn drives (using new beta software) with jitter scans performed on BenQ drives.

My post is in answer to this post by scoobiedoobie:

Agreed so far - we need to have more jitter scan comparisons, but I'm starting to believe BenQ jitter scans more now that I have seen the same on LiteOn drives.

I still think that BenQ drives sometimes reports PIE/PIF values "unfairly" for burns made in some other drives, independently of the jitter level, but I'll return to that when I have made some more scans to confirm what I have seen recently.

The higher the jitter level the more difficult it is to read a disc at high speed.

That's why you can have a disc with high jitter that still scans with low PIE/PIF levels at low speed.

But if you scan the same high-jitter disc at high speed (12x or faster), you will very often see much higher PIE/PIF levels - especially near the outer edge of the disc.

I have seen this behaviour many times on my Plextor drive, and to a lesser degree on my LiteOn, BenQ and NEC drives.

So performing a disc quality scan at 12x or 16x is an indirect way of detecting high jitter; if the PIE/PIF levels don't rise near the end, the jitter is not extremely high, but if the PIE/PIF levels do rise near the end, the explanation could be high jitter (or something else).

At least as likely to be something else IMO, simply because of the higher speeds alone you will usually see more errors reported. I certainly agree that you'll nearly always see an increase in reported error levels as you read at higher speeds, particularly when approaching the limits of the drive. But I would not rely upon an increase in error levels at high speeds to judge jitter levels. Yes it could be from high jitter, but simply trying to read data at high speeds is going to create more difficulty for the drive, regardless of jitter levels, and therefore higher reported errors. As an example, I can scan a disc at 16x that has very low jitter, and the higher speed alone will trigger higher reported errors.

I do have a hypothetical question. if you have a physically good disc (balanced, no physical scratches), I'm going out on a limb and saying then higher errors are probably due to asymmetry, land/pit length and width. However, if data-clock jitter is the standard deviation from the "expected", shouldn't asymmetry affect jitter values? Also shouldn't beta and TA test (not sure what liteon calls it) be related then? I'm hoping that DVDScan's major drive ejecting bugs are fixed soon so I can do some of my own tests. I would like to compare some benq vs plextor vs liteon in beta/jitter scans.

it's getting late and my mind is slow.

Has anyone here tried scanning on the Aopen 1648 AAP? this drive reports Jitter aswell (even though it's only a DVD-ROM drive).

I did say that it was an indirect way of detecting jitter.

My main point being that you can use it to detect the absense of high jitter, if you scan the disc at high speed and there is no rise in PIE/PIF levels near the outer edge!

My first input in this "gurus" thread (woaw, that was a long and enthralling reading! )... please bear with me.. Yes, at least in my 1650 errors are higher near the end @12X scanning and even more @16X scanning. But I noticed that this increase is limited with some discs, and huge with other discs. Intuitively, I got used to consider that discs showing a limited increase in errors @12X and @16X were somewhat "better" discs, due to the physical characteristics of the disc or due to the quality of the burn, this I have no idea.

So now DrageMester's input had me starting to test a handful of discs at higher speeds, to see if I also find this correlation with jitter... I will report my findings.

I have the same opinion - discs that show a graceful degradation (or no degradation) in PIE/PIF quality when scanning at higher speeds are better.

I no longer judge burning quality solely on PIE/PIF scans at low/medium speed, but also on how they scan at high speed (12x) and of course Read Transfer tests.
Looking forward to it!

Sure, it is perfectly logical to believe that a disc that tests better at higher speeds than others is a better burn and/or easier to read disc, even if they test similar at slower speeds. I do run some PI/PIF tests at full speed and some discs test nearly the same at 16x as they do at lower speeds, while naturally others see increases. Keep in mind, once jitter reaches about 12% in Benqs, the errors reported become inaccurate and cannot be a fair way to judge the disc. Below 12% and they work reliably.