CDFreaks Presents: Home PI/PIF scanning article

CDFreaks Presents: Home PI/PIF scanning article - Who to believe?

You can read the article here
Please feel free to comment on this article in this forum thread.

Nice one! Could be really handy! :flower:

Cool! Finally an official article! :slight_smile:
Thanks guys!

I’m reading it now :slight_smile:

Thanks Dee :bow:

Just read the whole Article.

Very well done and informative.

It is quite nice to see an article amassing all the respective burners commonly used for PIE/PIF scanning (BenQ, NEC, Plextor, LiteOn). So far, here’s some observations of my own:

With burning in the 1640, for yuden000t02-00: all burners except the 760 show the 4.0 gb PIF spike; the LiteOn reports the least PIE and PIF (but only 2 less PIF than the 760). The 760 also reports a smoother beta graph for the 1640 burn than the H10 burn

Burning the T02 in the H10 and scanned on the 1640 made the H10 burn look like crap; the PIE spike is reported at the same spot on the 1640 and NEC4570A, but is reflected as a PIF spike on the LiteOn 16H5s; the 4570 and 16H5s report about the same occurences of PIF clumping from 3.7gb to end, whereas it appears not to be reflected in the Plextor 760; interestingly the 760 reports the least PIF here. While the PIE spike above isn’t reflected in the 760, if the scale is accurate and I read it correctly, it is accounted for on the Beta/Jitter graph; the LiteOn 16H5s still reports the lowest PIE, however…

Burning with the LiteOn 16H5s: 1640 reports a PIE mountain, leveling off at ~ 1GB (as do the 16H5s and 760), and also reports PIF clumping up to .5 gb of the burn; no such report from 4570A nor 16H5s. Again, the 16H5s under KProbe shows least PIF total.

With NEC-4570A: The jitter shift downward in the 760 is more or less represented by PIF spike on 1640; only possibly indicated by PIE spike on 760 and 16H5s. The 760 shows highest PIF total, with 16H5s still lowest, but the 4570A and 1640 are within 4 of each other.

With Pioneer DVR-111: 4570A and 1640 PIF totals are within 12 of each other; only the 760 and 16H5s seem to report PIF clump nearly at the end of the burn. The LiteOn again reports lowest PIE/PIF under Kprobe.

760A: PIF reported within 6 on 1640 and 4570A; the only curiosity is the 1640 reports a small PIF clump at the end of the burn, but no other drive shows this. 16h5s again shows lowest PIE/PIF totals.

I really, really like articles like this.

I especially like how you help explain what the graphs mean and what specs folks should look towards when trying to determine what actually constitutes a quality scan.

Thanks very much.

Here is a bit from the front page that I like in particular:

Easier explanation on how to read the test results.

Maybe this has got too technical, and you are wondering what to look for in KProbe reports?

Use this as a guideline for good discs:

PI (Parity Inner): No larger areas on the disc should exceed 280 PI-8 errors, do not worry too much about high single spikes that exceed 280.

PIF (Parity Inner Failures): No larger areas on the disc should exceed 4 PIF-1 errors, do not worry too much about high single spikes that exceed 4.

And as always; lower is better

There is also the matter of scanning drives following the criteria for Disc Quality Scanning according to the ECMA standard. One of the requirements of this standard is for the scan to be done using a CLV reading method. The NEC drive is not able to perform this task at a reasonable scanning speed, (by reasonable we mean 2x – 4x scanning speed).

Your results are clear. Problem is, I can’t really take this as an objective test.

Here you are quoting a requirement from the ECMA but you fail to adhere to this requirement on drives that are clearly capable of doing so.
You also fail to mention that that same standards require 1x CLV as the scanning speed.

Forum standards for scanning speeds should have had no part of this test, this shouldn’t be a popularity contest.

If you want to give an objective comparison, you should scan at the lowest common [B]CLV[/B] speed of the drives, even if that means 1x.

I realize this takes time but none of us are going anywhere… :wink:

The only thing that is special about 1x CLV scanning is that it’s the original reading speed for DVD media and the one mentioned in the ECMA standards.

There’s nothing about 1x scanning that makes it more “correct” than other scanning speeds. Just because CATS scanners scan at 1x doesn’t mean that they somehow see the “true” quality of a disc or that scanners scanning at higher than 1x show a “false” view of the quality of a disc. It only means that CATS scanners are following certain standards defined years ago.

There is no single “true” view of the PIE/PIF on a disc, because the PIE/PIF are not actually “on the disc” but occur only as the result of a drive reading the disc and having trouble reading everything correctly. So PIE/PIF not only reflect what’s on the disc but also how the drive reading the disc is performing. Reading/scanning speed also influences the PIE/PIF occurring.

CATS scanners are of course more consistent than the consumer drives used in this article and on our forums, and they can also measure many characteristics that the consumer drives cannot measure.

Some of our users have found that high-speed PIE/PIF scanning (12x or faster) can sometimes show problems that are not seen in the low-medium scanning speeds. This doesn’t mean that high-speed scanning is somehow more “correct” than low-speed scanning, but performing scans at different speeds may show a more complete picture of how a disc behaves.

Scanning a disc in multiple drives may provide an even more complete understanding of how the disc behaves.

But it all takes time of course.

It is my current opinion that 1x scanning is not only too slow to be practical for everyday use, it may also be the least useful scanning speed for some drives because it shows a “best case” scenario for many drives - not all drives however, because some modern drives may actually perform worse at the lowest speed compared to when reading at medium or high speeds.

The article shows different drives scanning at different speeds, and those speeds are in common use on our forums which makes the comparison both valid and useful. Using a 1x scanning speed would have been counter-productive in the sense that almost no home user would bother using such a slow scanning speed.

This subject is much more complex than just scanning a disc at 1x in one drive and then knowing “everything” about the quality of that disc! :slight_smile:

I think you missed my point. I’m not saying it should have been 1x but if that is the only speed in common then so be it.

Analogy would be in Government automotive crash tests, some cars are run into the wall at 80 mph while others are run into the wall at 10 mph and then trying to give an objective review of their crash worthiness…

Good review overall. One question though, why not use 4x or 6x CLV with the Benq? As you even say in the conclusion of the Liteon, you say that you consider CLV as a must for reliable scanning, only to use 8x CAV anyway with the Benq. 6x CLV is all I use since it was introduced, as not only does it give the consistency advantage of using a constant linear velocity across the entire disc, it is also faster than 8x CAV (the faster test time is from memory and was compared awhile ago but I believe it to be correct). For the same reason of consistency, I usually use 4x (CLV) on my Liteon 160P6S, and additionally my 4x Liteon scans are in closer agreement to my Benq drives and their scans vs. 8x Liteon scans, which further supports the logic in using CLV when available.

It could also be pointed out that Benq and NEC drives have a greater sensitivity to high jitter levels and that is often the source of their occasionally erratic error reporting, whether the jitter levels are accurate or only perceived is somewhat debatable though and opens up a whole new discussion that would not be entirely fit to the article. For some, the ‘why’s’ of a drive’s scanning performance and why the results can become skewed are not of their interest, only how accurate they ultimately are. The main reason for the article is to simply test and compare results between drives, not necessarily to go into what causes differences. High jitter levels can sometimes effect a disc’s readback performance even with low reported error levels though so it’s something worth considering when testing your own discs.

And that explanation is in every one of our burner review articles! :wink:

Why did you only use ‘good accuracy’ in Plextools instead of ‘high accuracy’ ?

Great article Dee! Maybe I should buy me a LiteOn 16H5s drive also.

To save scanning time probably.

Using Good Accuracy instead of High Accuracy saves 1/4 hour per scan x 2 scans per DVD x 4 media x 6 burners = 12 hours of scanning time saved.

any difference in the result using good instead of high?

High Accuracy scanning has uh… higher accuracy?! :stuck_out_tongue:

Good Accuracy samples only half the ECC blocks on the disc, so in theory you can miss some very brief PIE/PIF spikes or POF.

If you’re going to use a Plextor drive for scanning I would recommend that you run at least the Sum1 (PIF and POF) test at High Accuracy, and then you can run the Sum8 test at Good or even Medium Accuracy to save time. That way every ECC block will be sampled and checked for POF, you won’t miss any single PIF spikes, and you still get a PIE graph that is very close to the High Accuracy graph.

BTW when PlexTools performs sampling in e.g. Good or Medium Accuracy, and thus checks only half or one-quarter of the ECC blocks, you might think that it reports too few PIE/PIF. But fortunately PlexTools compensates by scaling the total PIE/PIF by a factor of 2 or 4 etc. so that total scores are comparable even if you don’t use the same accuracy setting.

Personally I use PxScan/PxView instead on my PX-712A because the tests are more automated, and the tests data is saved in such a way that the graph can be scaled and manipulated at will afterwards.

Here’s an example of such a scan:

Hi :slight_smile:
An intersting “spin” of this topic.
As such excellent for forum members. A “definitive” guide, probably.
Well done Dee. :clap: :iagree: :bow: :bigsmile:
However, as a truly definitive guide. It merely scratches the surface. (Not surprising as this is a monumentual task to take on comprehensively. The results of which would probably go over my head).
pchilson’s post is one of the only to (possibly the only one thus far) offer a constructive criticism & should been seen as such. So as to encourage enlightening/informative debate & not tit for tat posting.
Once again many thanks to Dee in even attempting such a topic. To present it in a clear well thought out manner. Making for an excellent reference point for this forum’s (no doubt other’s too) use. :clap:

Thanks everyone for the comments. I will do my best to answer the questions asked so far.

Regarding using 1x scan speed for all drives.
This was a no win, no win situation. Had i used 1x for all drives, members would have asked why the tests weren’t conducted using the scanning speed standards on the forum. And i would never ask members to conduct 1x scans so they could compare their own results with the ones in the article.

Regarding “good accuracy” with the Plextor tests.
As DrageMester has already stated. It was simply a matter of saving time. As a working mother with a family to look after, time is a very precious commodity. I also wanted to make sure that when a disc was burned, i had time to scan the disc on all the drives within a reasonable amount of time. I feel this was important to make the test fair for all the scanning drives.

Lastly i want to state.
This article is not a bible and the last word on Disc Quality Scanning. It’s only meant to be a guide. Each member will take what they want from the article and use which information they feel is relevant to their own needs.