But what do the scans really tell me?

vbimport

#1

I’ve been reading about scans and PI Errors and PI Failures for days and I cannot get any real world appreciation of what these errors and failures mean to me in terms of readability of the burned discs. It escapes me as to how one program can read the disc sufficiently to verify a successful burn and the next program encounters so many errors that it can’t even complete a scan. Follow me here and tell me where my logic is failing.

I burn and verify the disc using ImgBurn. I get no errors, see nothing unusual and get a success message at the end. That seems to tell me that ImgBurn was able to read what it just wrote and the read data still agrees with the original file. True? There’s no indication of how many attempts were made to read the disc and maybe ImgBurn had to try an exhaustive number of times to read it, but eventually, it was successful without outright failing.

I then run a Transfer Rate Test in DiscSpeed and get what looks like a nice relatively smooth curve. DL discs usually show a slight dimple at the layer break, but there are no real spikes of any size anywhere. That tells me that the drive was able to read the disc at a uniform rate. I guess it’s not checking the validity of what it got, but it knows it got something and moved on. Does the TRT have any impact on the quality of the image on the disc? Or is it simplying indicating that the drive recognizes data and can transfer that data, good or bad, at a constant rate?

Then it gets interesting. I move the disc to my (externally connected) BenQ DW1655 and run a Quality Scan. Everything will usually hum along nicely until it gets close to the outer edge of the disc and the fireworks begin.

So how is it that ImgBurn and my Pioneer burner can read the disc and successfully compare its contents with the original image file, yet the BenQ can’t even read whatever data is there without reporting errors galore?

I’m not asking how to avoid the problem (I know, I know, buy Verbatim and use a Sharpie but that’s kinda like painting your BMW with a 3" paint brush and house paint, isn’t it?), but I am trying to understand what it all means.

Thanks for any sense you can bring to this.

Ray


#2

[quote=NOTS3W;2067023]So how is it that ImgBurn and my Pioneer burner can read the disc and successfully compare its contents with the original image file, yet the BenQ can’t even read whatever data is there without reporting errors galore?[/quote] It’s similar to how one car may be able to drive round a race track with no problems at all while another car loses the grip in a corner, driving off the track and ending up as scrap metal.

The drives each have their own view of the readability of the disc, both views are subjective in nature (just like each car has a subjective “opinion” about the drivability of a track), and each view can be considered equally valid.

If one drive says the disc is easily readable while another drive says that it isn’t easily readable, then the conclusion would be that the disc can be problematic in some drives.


#3

I’d buy that, except that until a week ago, I only had one drive, the BenQ, and got similar results. It would burn and verify just fine, but the scans were sometimes good, sometimes not (media dependent more than anything else, I’m sure), just as I’m seeing today.

A week ago, I installed new Samsung and Pioneer drives and moved the BenQ to an external enclosure for scanning only. The results are not much different.

I suppose it could be that the BenQ isn’t doing a good job of scanning anymore and maybe I’d get more consistent results with a new (LiteOn?) drive for that purpose. I’m not trying to fool myself with falsely better scans, but from some of the horrible scans I’ve seen, I’m surprised the disk could be read at all by the Pioneer burner and ImgBurn during the verify. So either I’m getting falsely poor scans or I’m not understanding the process.


#4

You should be able to help determine if it is a false positives by re-scanning some discs you had scanned when the BenQ was internal.

I have used my BenQ as an external scanner before and didn’t have any issues.

Also with a registry edit you can scan with the Samsung.

[QUOTE=NOTS3W;2067055]I’d buy that, except that until a week ago, I only had one drive, the BenQ, and got similar results. It would burn and verify just fine, but the scans were sometimes good, sometimes not (media dependent more than anything else, I’m sure), just as I’m seeing today.

A week ago, I installed new Samsung and Pioneer drives and moved the BenQ to an external enclosure for scanning only. The results are not much different.

I suppose it could be that the BenQ isn’t doing a good job of scanning anymore and maybe I’d get more consistent results with a new (LiteOn?) drive for that purpose. I’m not trying to fool myself with falsely better scans, but from some of the horrible scans I’ve seen, I’m surprised the disk could be read at all by the Pioneer burner and ImgBurn during the verify. So either I’m getting falsely poor scans or I’m not understanding the process.[/QUOTE]


#5

Please post screenshots to go with your explanation, NOTS3W, so we can see what’s going on there. I get the impression you’re confusing scanning errors with reading/verification errors. A disc can have millions of scan errors and still be perfectly readable.


#6

If you’re going to use the BenQ as an external scanner, then connect it only via Firewire. USB2 is usually insufficient for external scanning (NEC chipset enclosures being the exception).


#7

[QUOTE=negritude;2067163]If you’re going to use the BenQ as an external scanner, then connect it only via Firewire. USB2 is usually insufficient for external scanning (NEC chipset enclosures being the exception).[/QUOTE]

My BenQ DW1650 is connected via USB2.
I’ve made comparision scans with internal and USB2 connection and there was almost zero difference.


#8

Even USB 1.1 is fast enough for DQ scanning. TRT is another matter, but I believe the OP is aware of that.


#9

I’d also like some pictures just to see a good example of what you mean.


#10

[QUOTE=Cressida;2067153]I get the impression you’re confusing scanning errors with reading/verification errors. A disc can have millions of scan errors and still be perfectly readable.[/QUOTE]:iagree: I was thinking along the same lines.

I guess it’s not checking the validity of what it got, but it knows it got something and moved on. Does the TRT have any impact on the quality of the image on the disc?
Would you be so kind to rephrase that question? I’m not sure what you’re really asking. I can already say that if you’re referring to the video image quality, there is not relation whatsoever between any of these tests and the video image quality.


#11

Thanks for all of the responses. Hopefully, I’ll learn something from this exercise. I spent the evening collecting some scans. See my next posts.

I need to try that. I did move the drive back inside the PC case for awhile and it didn’t improve things much. But I don’t know that I tried the same discs with it internal and external.

I’ve done that and you are correct, it will work. But I’ve been told to not trust scans done on the Samsung or the Pioneer, only BenQ, LiteOn, and Plextor, so I’ve been hoping to use the BenQ for that exclusively.

I truly wish I’d known more about external enclosures a couple of weeks ago. I thought that a sturdy enclosure was all that mattered. Mine is a $25 aluminum USB enclosure that, I’ve since learned, doesn’t have the best of chipsets. In fact, I don’t know what chips are in the thing, but I do know that TRT scans at speeds approaching 12x on SL discs will produce unattractive results and DL scans often flat out fail. The DQ scans look about the same as when the drive was internal, though.

Mine is connected via USB2.

Yes, I am. :slight_smile:

Coming shortly.

Perhaps that’s hitting on my confusion. My thinking is that when running a Transfer Rate Test, the drive is reading data and reporting how fast it can do so. How fast it can transfer data. If it has to read the same data numerous times in order to get valid data, that should slow down the rate at which it could transfer data. Or is that not logical? If that’s true, then wouldn’t I see a drop in the TRT graph? And without a drop, wouldn’t it suggest that the data is being read sufficiently so as to not impact the graph?


#12

Okay, so I started with a fresh burn and did some scans. I hope this helps illustrate my questions.

First, I burned a large DL Image. ImgBurn reported a successful verify and nothing the stats or logs indicates (to me, anyway) that there were any errors or anomolies. I take that to mean that the data ImgBurn wrote to the disc it was able to read back and successfully compare to the original.

The image was burned on the Pioneer drive. With the disc still in that drive, I did a TRT scan with DiscSpeed. Looks pretty good, I think, but you tell me.

I thought that meant that the disc was readable and didn’t have any significant points where it slowed down to re-read too many blocks. Is that not a valid understanding of the test?

Then I moved the disc to the BenQ and did the DQ scan also in DiscSpeed. Not pretty. To see if it mattered, I re-scanned it using CD-DVD Speed but that only got worse.

So my perhaps faulty assumption is that the disc that appeared to be successfully burned and verified and that “passed” the TRT, was not a very good disc when all was said and done.

DL BenQ DQ Stats (CD-DVD Speed).txt (433 Bytes)

DL BenQ DQ Stats (DiscSpeed).txt (433 Bytes)

DL ImgBurn Log.txt (3.06 KB)

DL ImgBurn Stats.txt (1.38 KB)






#13

Finally, I put the disc in the Samsung and tried a DQ scan using DiscSpeed. For some reason, even with the registry edits in place, DiscSpeed does not give me the option of running a DQ scan, but CD-DVD Speed does. The results were different but not “better”.

If it’s only a matter of being poor media (which I agree it may well be), would I see better ImgBurn results or a better TRT with better discs?

I want to try the same series of tests with some SL Taiyo Yuden TYG03 discs next.

If I’m misunderstanding the purpose of the scanning process or if I’m doing something wrong, please enlighten me.

DL Samsung DQ Stats (CD-DVD Speed).txt (402 Bytes)




#14

Ok, your scans are not the best but not extremely horrid either. Please know that ALL discs will have errors, thousands of them. It’s just how many that matter. Generally, PIE errors are much much less important than PIF, I cannot stress that enough. ’

If PIF errors are too high or too clumped up in one small area, you can have reading problems. As you can see with your Pioneer, it does have a blip in speed, just around where you get the PIF errors rising in the BenQ. But this may not always happen. Some drives can read through massive errors without hiccup. The amount of errors you have is not pretty, but I’m not surprised that multiple drives can read them without massive slowdowns or errors in TRT.

Here’s a DL scan for reference on a Verbatim. There are thousands of errors but this is considered low and very good overall.



#15

Dont even bother with scanning non-MKM DL media.
Ive created a thread a while ago about that topic.

I have DL discs that are TRT perfectly and are readable by any standalone I tried with 1000 PIE and 100 PIF at the layerbreak, others arent readable at all with 100 PIE and 10 PIF.

Just TRT your burned DL discs and if the TRT is fine, keep it :wink:


#16

[QUOTE=Womi;2067630]Dont even bother with scanning non-MKM DL media.
Ive created a thread a while ago about that topic.

I have DL discs that are TRT perfectly and are readable by any standalone I tried with 1000 PIE and 100 PIF at the layerbreak, others arent readable at all with 100 PIE and 10 PIF.

Just TRT your burned DL discs and if the TRT is fine, keep it ;)[/QUOTE]

Exactly, look at the scans of almost all non MKM DL media and you while see that while PI PO scans are terrible, media are in most cases readable with no problems. :eek:


#17

This is all good advice that may help me sleep better. :wink: Thank you all.

I had wondered if maybe I was just being too critical. It simply can’t be that every one of these discs is “bad” or the manufacturers wouldn’t be able to keep selling them. Obviously, as long as it can be played on a set top box, then the quality of the scan is of less importance. Still, with the emphasis on high quality media, I thought it best to strive for the best possible scores I could obtain. I don’t even want to think about how many discs I’ve discarded because of that. I’ll relax and see how the discs actually play before worrying so much about how they score.

Slightly off topic, I’d be happy to buy Verbatim which I acknowledge is a far superior media to the Moser Baers I’ve been using, if only they made a good printable surface. From what I’ve been told, their glossy hub printables remain tacky (can’t be stacked or stored in a sleeve) and I don’t recall if they’re water resistent. The printable side of the Moser Baers (The RICOHJPNs in my scans) is beautiful, glossy, waterproof, hub printable and they’re DL +R media. They don’t record so well, but they sure look good. LOL I hate to think of labeling even backups with a marker. If Verbatim would apply the Moser Baer surface to their discs, I’d be first in line to buy them. So it’s not that I have anything against high quality media, I just don’t want to consider media that doesn’t perform well on the label side, too. I’ve been convinced that paper labels are bad, but a compromise might be polyester gloss full face labels that could be applied to Verbatim discs and printed as a pintable disc in an inkjet printer. I just haven’t found any to try yet.


#18

[QUOTE=NOTS3W;2067489]For some reason, even with the registry edits in place, DiscSpeed does not give me the option of running a DQ scan, but CD-DVD Speed does.[/QUOTE]
DiscSpeed stores its settings under

HKEY_CURRENT_USER\Software\Nero\Nero8\Nero Toolkit\DiscSpeed

instead of

HKEY_CURRENT_USER\Software\ahead\Nero Toolkit\CD Speed

like CD-Speed does, so you’ll have to apply the patch again at the appropriate location there.

G


#19

I made the change under HKCU and under HKLM but always in the Ahead keys, not Nero. I’ll fix that tonight. Thanks for the tip.