What a good scan doesn't tell you:

vbimport

#1

Someone recently posted he had never seen a good scan of a bad disc. Well, here it is!

Suddenly started getting lots of errors with my CUSA Infome-R20. The following is a DVD ISO burned at 4x.

The Good

The bad: shows no files or directory structure.

The Really, Really, Ugly


#2

How is it possible to have 2899 PO Failures and still have a score of 97?

You sure you didn’t doctor that image up with paint?


#3

Well, aren’t you the cynical one. If I was going to play doctor, I’d give it a score of 98 or 99 and I certainly wouldn’t leave any POF’s on it.

FYI: Quality score is only based on the highest PIF spike as far as I know.


#4

No not cynical or sarcastic or meaning any disrespect. Just had no Idea that was even possible.


#5

I don’t think that the scan can be considered “good” since there are PO Failures.


#6

Quality score is not the most or only important thing. Any POF in DW1620 scanning is fatal enough. You posted a very bad disk scan, not a good scan. Your ScanDisc results actually look far better.


#7

I’ve pretty much given up on Quality scans
The “Quality” rating seems to be meaningless (Especially when scanned with a BenQ 1620)
I too can scan coasters on a BenQ and get a 93% quality score (you beat me with your 97%)
I just do the nero speed test now (on a nec3500 as it’s the fastest reader I own), no dips and straight line from 6.5x to 16x I assume dvdr OK.


#8

I scan on my Plex for TA quality. A 98% scoring disc can be judged as not good sometimes.


#9

The point of this post was just to re-emphasize that quality scans are no substitute for actually verifying your data.

I wish Nero let you verify a burn of an iso like DVDDecryptor does. I also do a surface/file scan in CD/DVD Speed of every disc. It takes longer but then I’m not burning hundreds of discs either. :slight_smile:

It had been awhile since I last used these discs and forgotten they burn great at 8x. The CUSA label says 4x, which is what I did and got 4 out of 5 coasters. So I guess safety message #2 is slower doesn’t necessarily mean better/safer. It all depends on the write strategies your system uses.


#10

Hmmm… anyone have scans with low PIE, low PIF, no POF and still have errors in ScanDisc?


#11

The latest versions of Nero do verify images. I prefer DVDDecrypter because it burns every image format I throw at it, unlike Nero. But I never use verify, I just buy quality media.


#12

I think if the disc quality test shows POF>0 the quality should automatically go to ZERO…I believe that POF are UNCORRECTABLE errors, right?


#13

Cannot repair PO F…bad disc.


#14

I think the author of CD Speed wanted the quality score to distinguish between bad burns, good burns and excellent burns, not use it to detect coasters.


#15

I think you are right on this. I regularly get “0” on quality with very nice scans that have a single high spike at the 0.25gig mark. These discs play beautifully, and the scan disk tests are all green. I’m told that it’s is an anomally when scanning an NEC burned disc with a litey drive. But, as I said the disc quality drops to “0” as soon as the spike appears. :iagree:
By the way, are those scans both from the same disk?


#16

I thin kthe key here is this not a good scan and the data is there on the screen…POF>0

maybe the author can set so a POF>0 gives a zero score


#17

Maybe the author made a choice here, in stead of a mistake. People who forget to open and close the tray before a scan, can get lots of POF’s when the drive tries to read unwritten sectors. They are usually inexperienced in reading scan results, so they might just throw away perfectly burned discs if the quality score is 0.
On the other hand, if you think you have made a good backup of your data and overlook the fact that there are (real) POF’s, you are also in trouble. Then again, you should always verify a backup.


#18

Hi free4all,

I too have experienced a similar problem, although not recently. But my situation showed 0 PO Failures. It’s the main reason that I always set Nero to verify my burns.

I notice you’re running a rather old firmware, B7P9. Does this problem reproduce with one of the later firmwares - say B7T9 or B7U9? I suspect that it might be the result of a firmware bug that could have been fixed in a later rev.


#19

Very Good Point


#20

I usually black out the quality score because it seems totally meaningless, as it only takes into account PI fails, and also ignores the fact that high PI spikes may be disregarded under the DvD book specs. Unfortunately, those people with little knowledge of disk testing tend to view the Quality score as significant in some way. (test disk written in NEC3500 at 12x)

Here, I demonstrate the pointlessness of the Quality Score, 3 scans of the same disc. BenQ 1620 quality scan, Liteon 811s quality scan & NEC3500 speed scan

BenQ 1620

Liteon 811s

NEC3500A

Same disk, Liteon says Quality 0, BenQ says Quality 93, NEC reads disk at top speed, so what is the significance of the Quality Score … NONE

Also according to the 3 scans
The Liteon 811s says disk perfect at start, failing at end
The BenQ 1620 says disk failing at start, perfect at end
The NEC3500 says disk perfect all the way through

But if you use your eyes and look at the PI errors graphs, you can see they are both very similar, with only the Liteon going a bit funny at the end.
By the way, this disk is perfectly good and reads well in evey player I own.

I am beginning to doubt the PI fails and Quality score are significent in any way, but do like the way the Jitter graph shows me the write speed of my NEC in steps starting 6x, 8x, 12x