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Writing quality issues...and big surpizes - 5/11/2004 8:37:32 PM   
emperor


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Many people are wondering about KProbe/CDSpeed scans, how accurate are compared with Professional CD/DVD Testing equipement. The answer is not a simple one but rather complicated...We decide to begin a deep search and today we present our first results. We are waiting for your comments and remember not to make any quick assumptions.

a) Test parameters

We measured a disc with SA300 system @ 1X and with LiteOn LDW-811S at various reading speeds (1X, 2X, 4X, 6X, 8X, MAX). We used patched firmware(s) that allows 811S series reading DVD recordable media up to 8X ( for comparison levels with the newest 812S LiteOn series).

* DVD Limits: PI Sum8 error rate DVD+-R limit is 280, while PIF 4.
* Note: KProbe reported PO errors are actually PIF errors, keep that in mind...

Reference measurements
* PISum8



* PIF



Attachment (2)

< Message edited by emperor -- 5/12/2004 4:43:35 AM >
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RE: Writing quality issues...and big surpizes - 5/11/2004 8:54:42 PM   
emperor


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b) LiteOn LDW-811S results

* Read Speed MAX (3~8 CAV) - no removal of high spikes



* Read Speed 6X (2~6 CAV) - no removal of high spikes



* Read Speed 4X (CLV) - no removal of high spikes



* Read Speed 1X (CLV) - no removal of high spikes



- Comparing Results

Someone can clearly notice that when scanning the specific media at 1X, 4X we simply lost the raisen trend of PISum8 at the outer area of the disc. In terms of absolute values, the LDW-811S reported around 4X less PI Sum8 errors, when reads the specific area. At 6X (CAV) the raisen trend its still there, when at 4X/1X we got a perfect scan. Troubled? Good, let's continue...


Attachment (4)

< Message edited by emperor -- 5/12/2004 4:04:09 AM >

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RE: Writing quality issues...and big surpizes - 5/11/2004 9:05:23 PM   
emperor


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c) LiteOn LDW-811S results PO vs. PIF

* Read Speed MAX (3~8 CAV) - no removal of high spikes



* Read Speed 8X (3~8 CAV) - Removal of high spikes



* Read Speed 4X (CLV) - no removal of high spikes



* Read Speed 1X (CLV) - no removal of high spikes



- Comparing Results

Looking the reference graph, we can notice that at MAX speed, the trend is there, however with the regular high spikes (due to mediatek chipset bug). After removing the high spikes (8X reading speed), the two graphs, not only look like the same but also reached the same error rate level. At 4X/1X speeds, again the rasien trend at the end is not present.

Totally lost? The party continues...


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< Message edited by emperor -- 5/12/2004 4:15:16 AM >

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RE: Writing quality issues...and big surpizes - 5/11/2004 9:19:13 PM   
emperor


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d) LiteOn SOHW-812S results PI Sum8 vs. PI, PIF vs. PO

The newest LiteOn DVD recorder comes to give another interesting side-effect...How the error rate changes (increases/decreases) between the previous and next (drive) generation.

* Read Speed MAX (3~8 CAV) - no removal of high spikes



* Read Speed 8X (3~8 CAV) - no removal of high spikes



- Comparing results
The LiteOn SOHW-812 reports low PI error rate that comes in direct conflict with its older brother (LDW-811S) and SA300. There is no indication that the PI error rate will rise at the end of the disc

* Read Speed MAX (3~8 CAV) - no removal of high spikes



* Read Speed 8X (3~8 CAV) - no removal of high spikes



- Comparing results
Again, the LiteOn SOHW-812 reports low PO (PIF) error rate that comes (again) in direct conflict with its older brother (LDW-811S) and SA300. There is no indication that the PO (PIF) error rate will rise at the end of the disc

....to be continued!


Attachment (4)

< Message edited by emperor -- 5/12/2004 4:47:05 AM >

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RE: Writing quality issues...and big surpizes - 5/12/2004 4:11:05 AM   
eldritch


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One thing that we all must have in mind is that the professional equipment like CATS or Expert is based on reference reading or recording pickups. This means that the reading mechanism is not designed to allow for defects in the recording or medium. On the other hand consumer drives and players are designed to playback as many discs as possible bypassing small defects in the recording. If this was not the case playing back and recording would be a very frustrating experience.

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[Deleted] - 5/12/2004 5:08:05 AM   
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RE: Writing quality issues...and big surpizes - 5/14/2004 6:07:18 AM   
Halc

 

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Thanks for the great scans!

As usual, CDR-Info is pushing the limits and finding out new stuff, instead of just trusting blindly the kProbe results. I really applaud you for doing this. I couldn't afford it myself (my cd-r testing cost me enough as it was).

Now, I've been thinking about this issue as well and your test seem to correlate with my hypothesis.

KNOWN FACTS
- Causal reasings (PI/PO/PIF/POF) error rates are caused by mismatch between low level values of the disc (jitter, reflectivity, etc.) and the tolerance margins for those levels by the reader.
- LiteOn dvd-drives have relatively high jitter tolerance margin (sometimes twice that of lesser drives)
- Many dvds burned with Lite-On dvd burners measure/read quite well on LiteOn drives, but are utterly and totally unusable in almost any other drive (i.e. disc not recognized, video image becomes erroneous, etc.)
- CATS scanners measure the disc in accordance to published (and sometimes in-house determined) specifications and limits. These limits or guideline values are imposed on the low level disc performance values. Error rates are just a result of these. Most CATS operators look at the low level results and based on those, adjust their production line. PI/PIF values are an overall error level check, not the be-all-end-all of testing.

HYPOTHESIS

1. At lower rotational speeds LiteOn drives can easily compensate for bad low level values on the burned disc. For instance, jitter, which usually rises towards the end of the recording (outer rim of the disc) is more easily to keep under check at 1x

2. CATS scanners mark DC jitter values over 9,5% (? at least this was done on the C't tests). On a general level DC jitter should remain below 15% average. Lite-On drives can tolerate jitter up to 20% average.

3. At higher speeds both servo control accuracy and jitter tolerance margins come into play much more, especially at the end of the disc (were jitter values often rise). This results in rising causal error rates when higher rotational speeds are used and the average jitter tolerance of the drive is diminished. The end result is a significant rise in error rates towards the end of the disc at higher scanning speeds.


Now, jitter is also not be-all-end-all low level measure. I'm postulating that other low level measures in consumer dvd-rw drives have somewhat similar correlation: the drives themselves are able to tolerate much bigger low level deviations as readers than what the specifications really need.

I'd suspect it's easier (at the time of this writing) to produce a dvd-rw writer that reads the disc burned on itself properly (i.e. high reader tolerances) than actually make a good burner that produces so small low level deviations on the burned disc that the resulting disc can be read in any drive.

This is one of the reasons I don't recommend LiteOn for a beginner (on dvd-burners): it can burn crap discs, but it can still read them back faultlessly and even produce misleadingly good measurement results. Or to be more honest, the readings are not necessarily misleading, it's just that the people take them for what they are not. They are not an universal measure of disc readability or burn quality, like many people in many forums tend to think.

I'd rather recommend a drive that is an average reader, but an excellent burner: it will catch its' own crap burns much faster and provide much better compatibility over a larger number of drives. Two such drives IMHO are LG GSA-4081/4082 and BenQ DW800A/DW822A (based on low level measurement data on various discs, as published by Pc Professional and C't Magazine).

I think it is great that CDR-Info has again pushed the mark and shown us how to do things right.

Please provide more scans, if you can.

What I learned with my CD-R test (kProbe/PlextoolsPro/CATS correlation) was that:

1) Plextor Premium, LiteOn 48327S/52327s can still read error free disc that CATS even refuses to recognize

2) Sometimes Plex Premium vs LiteOn 52327s scans were totally different. More often CATS scan would reflect the values that the Plextor got.

3) Not all badly burned discs were always most readable on LiteOn. Some discs were more readable on Plextor Premium and horribly useless on a LiteOn. CATS scan would then correlate more with LiteOn. This seems to indicate that the drives in question had different low level tolerance margins for various low level measures. Plextor may excell on some values, while LiteOn on others.

If you can, please also test on Optorite, because apparently it has much lower jitter tolerance margin than what LiteOn burners have. It should (hopefully) provide PI/PIF scan more in line with CATS scans.

Also, I'm sure you know this, but CDSpeed 3.0 beta can provide some sort of jitter measures from Nexperia chipset drives (NuTech, Philips, BenQ). However, nobody knows if these jitter values are anywhere useful/accurate or just "pretty graphs" that tell us pretty much nothing :)

So, if you can do it in the future, consider doing low level scans and comparing those as well.

Thank you again for a great discussion opener on the issue!

PS My status went to "new member, 1 post"? Was this because I had to reset my password?


< Message edited by Halc -- 5/14/2004 6:12:34 AM >

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RE: Writing quality issues...and big surpizes - 5/14/2004 10:14:11 AM   
Dolphinius_Rex


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Hey Halc! And welcome to our new forum Your old post number *should* have carried over, if you give SP a shout, he might be able to do something about it for you.

If you take a quick look around some of the other topics, Emperor has also posted comparison scans of the Nutech w/CD Speed 3.0 against the CATS Analyzer, which I think you'll find interesting.

At this point, I've pretty much lost any faith in the scans produced by K-Probe with any LiteOn drive! I'm hoping, *HOPING* that the Plextor 712a is going to be better, but I'm not holding my breath either. Both the Plextor 712a and the Optorite will also be compared against the CATS in the next little while though, so we shall see

Stick around, it'll be worth it!


_____________________________

Canada; Leading the world in being just north of the U.S.A.

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RE: Writing quality issues...and big surpizes - 5/16/2004 2:56:45 AM   
JeanLuc

 

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Thanks Halc(yon) for clearing up things a bit ...

I always stated that K-Probe has one purpose only ... to count error levels being reported by a LiteOn drive. No more, no less. The fact that PI failures and PO errors were being confused from the start has no positive influence on my trust in this program either ...

The fact that nearly any LiteOn DVD writer failed to produce in-spec DVD's (I had a 411S and really wasn't satisfied with it) when these were being scanned with a properly aligned/calibrated CATS system shows me that LiteOn must put some hard effort in DVD/RW drive improvements before even the LiteOn zealots start to "see the light". From my personal experience with LiteOn CDRW drives (their writing quality is undeniable), I am sure their engineers could handle this, but my skepcticism towards this topic points at (what I call) the "speed" race ... instead of producing a high-quality 8x model as a basis for future drive developments (like NEC or BenQ), LiteOn releases a Dual Layer writer ... not too smart, if you ask me.

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