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Reading speeds for PI/PIF scans... - 6/8/2004 6:38:44 PM   
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I have seen that in many reviews, people still haven't realized the differences between reading speeds/models variations and give viewers a rather "false" image about the writing quality of burned discs.

What I mostly refear too, is the "famous" 4X CLV reading speed.

Myths:

- Some claimed that scanning at 1X will give them similar results to the CATS, since CATS scan at 1X CLV speed.
- Since 1X is time consuming, suggested to scan at 4X, since would save time and give more "reliable" results...
- LiteON drives report PI/PO errors.

What we have proven is:

1) Scanning at 1X/2X CLV with commercial drives won't give you the error levels that CATS reports.
2) Scanning at 4X CLV with commercial drives, also won't give you the error levels that CATS reports.
3) LiteON drives are not reporting PO errors, only PI/PIF errors.

The above reading speeds (not to mention that even 6X CAV) will "devaluate" the "true" error rates upon a disc. I am placing quotes, since there isn't any true or correct error rates, since are the result of the pickup/reading speed combination. Someone could say "correct", only the values are reported as from CATS, others won't.

From our reaseach and comparison we decided to use the 8X CAV reading speed with "selected" LiteON LDW-811S drives. Maybe not the best, but for sure are tested what exactly report. Also we are using Plextor's PX-712A that also gives interesting results. Most times when something "weird" shown at a KProbe scan, will also appear at the Plextools scan also.

Other facts:

- SOHW-832S showed that this drive, its not a good choice for scan discs, it shows extremely low error rates, especially at 4X...

As someone could easily understand, using the "correct" combination of reading speed and reader, can make a drive looking perfect (in terms of writing quality), when in reality doesn't...The disc that read perfectly at the specific drive, won't be read at others...

The research to find a "perfect" commercial reader for testing writing quality continues...

Your comments are most welcomed


< Message edited by emperor -- 6/9/2004 2:25:58 AM >
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RE: Reading speeds for PI/PIF scans... - 6/8/2004 7:11:12 PM   
Dolphinius_Rex


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Well said Emperor! Now let's see if people listen....


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RE: Reading speeds for PI/PIF scans... - 6/8/2004 7:28:24 PM   
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Dolphy our reasearch showed a "partial" reality, we are still searching this subject, but for sure, we are on the right track

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RE: Reading speeds for PI/PIF scans... - 6/9/2004 12:09:54 AM   
JeanLuc

 

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just a quick and dirty statement from me ...

You (and anybody else) won't be able to find a universal truth regarding the thing called "writing quality". "Pure" disc quality (in terms of "real" physical disc errors or low-level errors like mechanical, physical or geometrical anomalies may be measureable on calibrated test equipment but casual error counts (call it PI-Sum 8,PI/PIE/PIF/PO) at any reading speed do have only limited impact upon what is most interesting to anyone: disc readability and playability/comaptibility (although the PIPO tendencies are often quite interesting over the disc surface).

I have seen "horrible" K-Probe scans of CMC +R media with PI-Sum 8 levelling at some 1200-1400 (and PIF at 100-200) over the whole disc surface whild the disc was still readable in either my Plextor PX116A DVD-ROM (a rebadged Pioneer DVD-120), the LiteOn 411S or two standalone DVD players and I have also encountered Taiyo Yuden +R with extremely low error counts and skipping disc playback.

So, as a result of my experiences, the most interesting graph for me is still the good ole' Nero CD Speed transfer rate scan with a high sampling rate ... if this scan is smooth without speeddowns, I'm fine with it (and I know that the disc should be played back on my computer without problems at least).

CATS scans do show one interesting aspect for me ... due to the fact that calibrated readers are used for each scanned combination of write device/media, one can easily spot which media should be avoided for the specific device.

The other quality issue that is of high interest (at least, to me) is disc longetivity - but as we have seen with CDR media (where no universal truth exists either), only time will tell.

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RE: Reading speeds for PI/PIF scans... - 6/9/2004 4:59:52 AM   
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JeanLuc, thanks for your post. For sure there isn't a universal "truth" but there is something we learned from our tests, someone can easily mislead the writing quality results, in favor of one manufacturer than other...That is what have noticed and we own tell the world about it.

About the transfer tests, you are correct, i think we should add also them to our tests, probably an all in one transfer rate, using Plextor PX-712A, seem picky enough with various media

As for disc longetivity, you need special testing equipement, which costs much more what CATS do

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RE: Reading speeds for PI/PIF scans... - 6/9/2004 3:08:01 PM   
Halc

 

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Thank you for your hard work and preliminary summary on this.

I look at this from various perspectives. One could see three research questions here:


Question 1
Finding a single consumer test drive to be used in reviews that gives roughly similar results as a calibrated Pulsetec drive, using the scanning options your scanner operator has chosen

Question 2
Finding a set of tools that gives a good indication of a burned disc quality (but without being able to tell if the burner or the disc or both were good or bad), namely readability/compatibility in a wide range of devices

Question 3
Finding a set of tools that can be used to measure the burner quality AND the quality of media (as separate issues)

These are three different research questions, which must be tackled with different tools in order to be answered in a useful manner.

Sure, there is overlap between the tools and the test methods, but because what is being asked in each case is different, so are the tools to find out the answers.

Let me propose my current high level view answers to the above three questions. High level, because I may not be able to name names (i.e. tell exactly which drives/software/settings/etc to use in each case).


Answer 1
Question number one is what you have set out to answer and it looks like to me, that you've found a good candidate for a set of tools:

LiteON LDW-811S drive with kProbe at 8xCAV. Filling in with PX-712/Plextools Pro when there is reason to believe a scanning reliability is compromised (from your CATS reference perspective) with LiteON/kProbe scans.

I find several arguments in your favour:


  • it seems, based on your testing, that LDW-811S at 8xCAV does give reasonably similar error rates to CATS
  • Mediatek measures PI/PIF and not PO (so it's actually possible to measure against DVD-ROM and DVD+R limits of PiSum8(max)=280 and PIF_ECC1(max)=4)
  • scanning at 8x also stresses reading to such a degree that it simulates "difficult reading conditions" in real-life dvd-rom/dvdrw use



Answer 2
Question 2 is more complicated. For this, I don't believe that single one drive is good enough.

Let me be frank and say I don't believe even CATS with the current software version, using one set of parameters and one scan run, is enough.

A proper set of tools, without going overboard, would consists of perhaps something like the below:


  • your kprobe test setup from 1) to show how non-optimal LiteOns see errors on burns
  • Plextools / PX712 (or similar in the future) to give an indication of Plextor (and perhaps Sanyo chipsets in general?). Preferably with your hacked Plextools at a higher than 2xCLV scan speed, because discs do get read faster than 2xCLV in real use
  • CD Speed PIE/POE scan / Nexperia based drive (BenQ) to show how another family of chipsets/transport sees the number of errors. Perhaps this could even be used for jitter measurements (this remains to be seen)
  • CD Speed transfer rate graph with a "marginal quality" dvd-rom drive (don't know which one this could be) to simulate a sub-optimal reading situation
  • a rack hifi-player from one of the big names (Sony, Matsushita, Pioneer) for checking dvd player compatibility if desired (of course one could have several players, but even one would be great)


Answer 3
Question three is the most complicated to answer imho. Staying out of the realm of professional tools, I think something like the following could be devised in the future:


  • PIE/PIF/POE/POF scan results for discs for which the maker/model of the disc and the maker/model/firmware/speed of both the burner and the reader are known
  • transfer rate graphs (including elapsed time) to show transfer rates for various different readers
  • Hopefully some lower level indirect measures of tolerance limits for some major drives (i.e. Plextor 107 has a maximum jitter tolerance of 1X%, PX712 has 1Y%, LiteOn 851 does not like too much focus error, etc)
  • All of the above exported, uploaded and stored in a database
  • A statistical tool that looks (from the database) multiple burns using media A with various burners at various speeds using various firmware and being measured with various readers:
  • when the results from various sources start to correlate it can be reasonably safely assumed (after statistical analysis) that the media is good and being supported well.
  • When there is a great discrepancy in some drives being able read copies, but other drives failing, it can be analyzed whether the media is badly supported by other drives (or whether it is bad in itself).


Overall
Of course setup no. 2 is already a LOT of work for any single source / tester group. Too much, I think.

Number three is way too much work, but it could be distributed, if somebody set up the database and software makes enabled exporting of raw data in a known standard format.

The trouble is that the burning tools are a moving platform: new firmwares, new models, new versions of same discs (perhaps even with same media codes), different batches, etc.

It may not be possible to statistically analyse these results, because there may be too much data noise and/or there just isn't enough big of a statistical sample available from each set of burners/firmware/media, as they change too fast.

These are my initial rough thoughts at this time and by no means do I consider them the optimal solution as they are admittedly way too cumbersome. Also, I can't prove that what I've written above is all correct, as I've already learned quite a lot on the way and find my own initial thoughts from even a year ago to be overly simplistic or just plainly wrong.

However, I do believe that we should try to aim for something that is between 1) and 2) in terms of realibility and amount of work, or otherwise we will just end up measuring a number of errors that some unknown/relatively small number of drive sees on some particular burns.

Unfortunately I don't yet know what this "in-between" test setup could be.

Perhaps with further testing we could find, say three different drives, which are popular and which sometimes see totally different results from one same burned disc (because the drives have differing tolerance values).

Perhaps something like above could be a decent compromise between number of tests and reliability of the test results considering a larger population of drives and burns.

That's my two cents.

Best regards,
Halcyon


< Message edited by Halc -- 6/9/2004 3:19:33 PM >

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RE: Reading speeds for PI/PIF scans... - 6/20/2004 4:59:08 AM   
OC-Freak


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quote:

Myths:

- Some claimed that scanning at 1X will give them similar results to the CATS, since CATS scan at 1X CLV speed.


My thoughts: Probably not the same as CATS scans - but I thought it may be more comparable to CATS scans than a 4x scan.

quote:

- Since 1X is time consuming, suggested to scan at 4X, since would save time and give more "reliable" results...


My thoughts: more reliable than 1x scanning? Probably not - byt it saves a lot of time.....

quote:

- LiteON drives report PI/PO errors.


Wrong - that's an error in K-Probe, they reports PI corrected errors and PI uncorrectable errors (PI Failures)

quote:

The above reading speeds (not to mention that even 6X CAV) will "devaluate" the "true" error rates upon a disc. I am placing quotes, since there isn't any true or correct error rates, since are the result of the pickup/reading speed combination. Someone could say "correct", only the values are reported as from CATS, others won't.


The error scans only reflects a drives ability to read a certain disc. There is no warranty that another drive will report the same amount of errors on the same disc. The same goes for CATS scans - but those units are calibrated and is probably the most "correct" scanning units. There will always be some variations from drive to drive and disc to disc.....

quote:

From our reaseach and comparison we decided to use the 8X CAV reading speed with "selected" LiteON LDW-811S drives. Maybe not the best, but for sure are tested what exactly report. Also we are using Plextor's PX-712A that also gives interesting results. Most times when something "weird" shown at a KProbe scan, will also appear at the Plextools scan also.


8X CAV? How is that possible unless you use a hacked firmware? My 811S reads DVD-R/RW and DVD+R/RW media at 6x CAV only (starting at low 2.6x speed)........ Also the fact the plextor scans could somewhat be compared to Lite-On scans shows that there is some agreement/truth in the plextor/Lite-On scans.

quote:

Other facts:

- SOHW-832S showed that this drive, its not a good choice for scan discs, it shows extremely low error rates, especially at 4X...


Really? I did extensive testing before switching to using the 832S in my reviews and found it to perform almost identical to my previous scanning unit; the Lite-On LDW-411S with firmware FS07. My 811S has reported weird (scanning varied a lot depending on how it was connected to my computer, even master/slave on the same cable made a big difference) K-Probe results since day one so I've not even considered it as a K-Probe scanner.

quote:

As someone could easily understand, using the "correct" combination of reading speed and reader, can make a drive looking perfect (in terms of writing quality), when in reality doesn't...The disc that read perfectly at the specific drive, won't be read at others...


Very true!!! That is why I also include a reading curve in my reviews from a bit picky drive; the JLMS XJ-HD165H DVD-ROM. Due to requests from some drive manufacturers (They claim the 165H is a unreliable reader ) I'm considering switching to use the Plextor PX-712A for doing the reading curves.

I really hate reviews that only shows K-Probe scans and not reading curves for every disc - as I've sometimes seen serious readback problems with discs that turns out quite ok in K-Probe. There is even some sitest that edit the K-Probe images to exclude speed settings and drive used to do the scanning......

quote:

The research to find a "perfect" commercial reader for testing writing quality continues...


True.


< Message edited by OC-Freak -- 6/20/2004 5:04:23 AM >

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RE: Reading speeds for PI/PIF scans... - 6/20/2004 1:06:44 PM   
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quote:

ORIGINAL: OC-Freak
My thoughts: Probably not the same as CATS scans - but I thought it may be more comparable to CATS scans than a 4x scan.


Test results showed that isn't much true, maybe consider changing your guides or adjust them to newest test results

quote:


My thoughts: more reliable than 1x scanning? Probably not - byt it saves a lot of time.....


Of course 4X saves time, but...again isn't much "reliable"

quote:


Wrong - that's an error in K-Probe, they reports PI corrected errors and PI uncorrectable errors (PI Failures)


Correct, i said that KProbe cannot report PO errors, maybe people talked about PO errors and its rather weird that even KProbe author hasn't changed this, its rather misleading...

quote:


The error scans only reflects a drives ability to read a certain disc. There is no warranty that another drive will report the same amount of errors on the same disc. The same goes for CATS scans - but those units are calibrated and is probably the most "correct" scanning units. There will always be some variations from drive to drive and disc to disc.....


Correct, that's why we test our measuring devices vs. CATS, i have said in earlier posts that when time permits, we will perform more tests...

quote:


8X CAV? How is that possible unless you use a hacked firmware? My 811S reads DVD-R/RW and DVD+R/RW media at 6x CAV only (starting at low 2.6x speed)........ Also the fact the plextor scans could somewhat be compared to Lite-On scans shows that there is some agreement/truth in the plextor/Lite-On scans.


Yes with "patched" firmware, its stated at all recent reviews. Sometimes Plextor/LiteON scans seem to agree, sometimes doesn't, unfortunaly

quote:


Really? I did extensive testing before switching to using the 832S in my reviews and found it to perform almost identical to my previous scanning unit; the Lite-On LDW-411S with firmware FS07. My 811S has reported weird (scanning varied a lot depending on how it was connected to my computer, even master/slave on the same cable made a big difference) K-Probe results since day one so I've not even considered it as a K-Probe scanner.


I have posted many pictures showing that 832S, as expected reports much lower error rates than what 811S and CATS report, we are now testing DRU700A (another 832S clone) and results seem to agree...I have to dig a 411S drive to see what will report, hopefully soon

quote:


Very true!!! That is why I also include a reading curve in my reviews from a bit picky drive; the JLMS XJ-HD165H DVD-ROM. Due to requests from some drive manufacturers (They claim the 165H is a unreliable reader ) I'm considering switching to use the Plextor PX-712A for doing the reading curves.


Due to testing time, we decide to remove transfer graphs and instead place two scans, KProbe/Plextools and soon something else...

quote:


I really hate reviews that only shows K-Probe scans and not reading curves for every disc - as I've sometimes seen serious readback problems with discs that turns out quite ok in K-Probe. There is even some sitest that edit the K-Probe images to exclude speed settings and drive used to do the scanning......


Yes thats the problem, not universal "agreement" to what should be tested and how, everyone follows its own method, according to this research, its the way life goes, unfortunaly...

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RE: Reading speeds for PI/PIF scans... - 6/20/2004 1:15:50 PM   
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Halc thanks for your comments, sorry for my late reply, here are my thoughts and what we plan to do at the near future:

a) The KProbe/Plextools scans will be there. As you have seen the BenQ/BTC drives scan every 32ECC/40ECC meaning results will vary, also BenQ scan only at 1X~2X, too time consuming at my opinion...
b) Transfer graphs could be a nice idea, maybe with a DVD-ROM that can reach 16X with DVD recordable/re-writable (perhaps a Toshiba one?), we have to see which model/firmware exactly (fortunaly we have all access to all of them).
c) DVD Player compatibility tests, probably the most important one, since we test error rates but not how DVD player respond to them. The big question would be, which one we should use, a new or older model? Hard to answer, we have to check it...

And of course we will continue checking each drive abilities, compared with something that considered as standard (CATS).


< Message edited by emperor -- 6/20/2004 8:23:40 PM >

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RE: Reading speeds for PI/PIF scans... - 6/22/2004 2:03:49 PM   
Halc

 

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Yes, the BenQ speed and ECC sampling frequency limitations are quite a turn-off, aren't they?

Still, in addition to LiteOn and Plextor, what third option with remarkably different PUH/chipset is there? I mean an option that offers at least some level of PI/PIF/PO/POF scanning. And a one that is represented in various drives (like BenQ is on Philips/HP/NuTech and perhaps others as well?).

I really hope NEC and/or Pioneer would step up to the challenge and provide the needed hooks for CD DVD Speed and DVD Info Pro authors. I'm pretty confident the drives/chipsets themselves are capable of reporting at least some error data.

If NEC did this, I'm confident that half of the so called LiteOn camp would switch in an instant and never look back. To me the only reason to own a LiteOn is kProbe. Otherwise I think very little of their dvd drives (all of them).

But big companies... not responsive, thinking "not invented here", wanting to be secretive, afraid of givĂ­ng out "important" trade secrets... seen it all before, I'm afraid. So I don't hold great hope for Nec/Pioneer.

---

I also believe transfer graphs at very high speed could indeed show some additional useful data. Especially if the tranport/PUH/chipset was again from another manufacturer (i.e. Not LiteOn/Plextor/BenQ camps). Perhaps Toshiba, as you suggest.

At least it will be interesting to see your tests about this (as always).

--

DVD Player compatibility is difficult yes. One of the big ones that is missing from the burning scene, but ships _a lot_ of dvd players is of course Matsushita (i.e. Panasonic, JVC). Maybe a drive from them would be good.

The trouble is: how to test dvd playback compatibility?

Is the rudimentary "disc recognized by the player and starts to play back" enough?

It'd be very difficult (not to say cumbersome) to spot errors in playback, seeking, chapter jumps and other functions.

Maybe basic is recognized/both layers work test would be enough as it would at least weed out the worst offenders.

Anyway, thank you again for your work and thoughts on the issue.

You're taking this quality analysis to a whole new level and I'm really thankful for that (and for being able to learn from you on the side).

cheers,
halcyon

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RE: Reading speeds for PI/PIF scans... - 6/22/2004 5:40:54 PM   
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Halc, we could add some scans from NU drives BUT...The NU 082 drive we have here ermm...cannot recognize many DVD-R media , i was waiting for a second drive, tested to work with DVD-R but there was some mess up so isn't here yet...NU is ok, cause you can scan at high speed -> less time consuming.

About the transfer graphs, i will look which toshiba drive gives the highest reading speeds and use that, not much time would spended for those tests anyway at 16X ->GOOD!

About compatibility with DVD players...Here is a total mess, we cannot simply stand in front of a TV and watch a movie for like 1.5hours with 25 discs, its insane, a quick test, fordward/backward, report skips/freezes could be enough among with normal playback at the END of the disc (where most bad things happen), but be warned that the used DVD player can affect the results as expected...

For example, we have a new Pioneer DVD player tested here, that can pass all Almedio ABEX Discs without any problems, has strong error correction mechanism, should we use it or not? Probably not, cause not many DVD players has this kind of perfection.

The quest continues... stay tuned!


< Message edited by emperor -- 6/23/2004 12:42:42 AM >

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RE: Reading speeds for PI/PIF scans... - 8/31/2004 9:23:51 AM   
rugger

 

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It shouldn't be too hard to test DVD player playback using a regular computer.

Most dvd-players have a removable DVD-ROM drive that uses an IDE interface and a regular 4 pin molex connector.

Just remove the drives from the devices you want to test, plug them into the computer's IDE bus, and run nero's scandisk and transfer rate functions on it. I clean read with no errors and no slowdowns can be considered a success. Read errors or serious slowdowns can be considered a failure.

Only problem is that most of these drives do not have an eject button on them, so you have to ask the computer nicely to open them up when you want to use them :D

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RE: Reading speeds for PI/PIF scans... - 8/31/2004 10:53:22 AM   
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rugger that is another option, however some DVD players don't include consumer DVD-ROM drives

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RE: Reading speeds for PI/PIF scans... - 9/27/2004 8:24:11 AM   
LOU

 

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@emperor

thanks a lot!

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