This is the second part of the test results from PX-712A and SA300 series.

* Reference Scan



* PlexTools v2.12



The PX-712A aborts the measuring process around 3.5GB reporting un-correctable reading error...

* Reference Scans





* PlexTools v2.12



Again PX-712A aborts the measuring process reporting a uncorrectable read error.

(in reply to emperor)

I just love Plextools!!

(in reply to emperor)

I wonder why 712SA fails to read the whole disc?

Based on the CATS scans it probably isn't too high Jitter/Asymmetry.

Must be something else.. hmmm...

regards,
halcyon

(in reply to Tony Veglis)

Halc, also i was surpized to see the PX-712A failing reading the disc, even the PI error rate is high, the Jitter/Assymetrt levels are ok...

(in reply to Halc)

Plextor stops for the same reason in both cases: It cannot make out the data (read) in this area.

(in reply to emperor)

The PI rates on both scans are way out of spec ... AFAIK, this leads to PI Failures and, eventually, to PO Failures ... a PO failure will most likely be noticed as some kind of CRC error IMO ...

Maybe the chipset Plextor is using cannot handle PI/PO corrections that well ...

(in reply to Tony Veglis)

Maybe just Plextor is more sensitive to such high PI error rate, leading to POF errors

(in reply to JeanLuc)

I think that's thinking the whole issue backwards.

PI/PO errors don't cause the drive to fail to read the disc. PI/PO are causal errors, that are calculated by the drives chipet, because the drive is unable to track/read/correctly detect the optically encoded analog waveform on the disc. Waveform isn't unambiguous anymore and bits become misinterpreted by the chipset.

PI/PO errors (unless intentional) should not be considered to "be" on the disc. Drives don't fail because of them, they fail due to lower level incompatibilities and the result is a rise in PI/PO rates, somtimes a complete failure to read/detect the disc at all.

Low level measures of a DVD disc, like eccentricity, vertical and radial deviation, refraction, thickness and birefringence can be considered properties of the media.

Indirect measures like asymmetry, DC jitter, reflectivity, tracking and push-pull are affected by the the low level characteristics of the media, the reading drive and the speed (and other variables) of reading process.

It is debatable whether the measured indirect properties like DC jitter (using a calibrated analyzer) are true measures of the disc or a combination of the disc/reader. Regardless, it can be said that incompatibilities between these indirect measures and the reading capabilities (tolerance margins) of the reading drive, are what cause bit level errors.

PI/PO errors are just the results of these incompatibilities.

But, as you can see in Plextor failure case by studying the jitter/asymmetr/beta results, neither jitter or asymmetry rise to the level that is over the maximum that Plextor 712SA can tolerate. If you look other discs succesfully scanned by the Plextor, they have similar/higher indirect measures for jitter/asymmtery, but still Plextor reads them fine. Study the jitter/Asym readings from CATS and jitter/beta from Plextor.

So, at least those two lower level values are not what are causing the reading problems for Plextor.

There must be some other low level mismatch between the media and 712SA that the Plextor is unable to tolerate, hence the rise in PI/PO and subsequent interruption of the testing altogether.

This is precisely the reason why PI/PO scans can be very misleading, because one drive can be sensitive to jitter (and get huge PI/PO errors on jittery discs). At the same time, another another drive can be very tolerant of jitter and gives excellent PI/PO results on that same jittery disc. That second drive can however fail on tangential push-pull issues of a different bad disc and then give high PI/PO error rates for that disc.

Of course this is an oversimplification, but it illustrates the issue, I hope.

To this day I have not seen a consumer drive that is superior (to competition) in it's ability to tolerate ALL lower level problems in reading. I know already from testing done by OSTA/c't that Plextor/Pioneer/LiteOn produce drives with relatively high jitter tolerance (up to 20% max average DC jitter). But we do not know their tolerance margins for other lower level measures.

As such, I'm intrigued why does Plextor 712 fail on that scan? What indirect measures go over it's capabilities?

best regards,
halcyon

(in reply to emperor)

quote:

By Halc

As such, I'm intrigued why does Plextor 712 fail on that scan? What indirect measures go over it's capabilities?

I totally agree with you on your points ... but I did not make myself that clear, I guess ...

You mentioned some types of disc errors (the ones you refer to as "low-level errors") that will force any given drive into it's built-in error correction mechanisms (be it CIRC or Parity - it doesn't really matter).

The above scans show Asym (Beta) and DC Jitter values, but not e.g. reflexivity, eccentricity, possible disc unbalance, temperature, sheer stress etc. - and we also do not know whether this specific PX-712A's reading is somewhat faulty when being compared to other drives.

As a side note: I remember from the CDFreaks forums that a lot of people reported read problems with their PX-708A ...

But I am truly surprised how good the Plextools PIPO/Beta/Jitter results cope with the SA300 scans (not in pure numbers, but in overall tendecy) ...

(in reply to Halc)

quote:

As a side note: I remember from the CDFreaks forums that a lot of people reported read problems with their PX-708A ...

..actually this is not a problem, all Plextor drives are very sensitive when it comes to reading. Physical and geometry problems of the disc may be neglected by a LiteOn drive for example, while you will get a read error with a Plextor. Of course, this behavior might be considered as a problematic for the user who needs his disc read.
But is it a problem when you are scanning for read errors?

(in reply to JeanLuc)

quote:

ORIGINAL: Tony Veglis

quote:

As a side note: I remember from the CDFreaks forums that a lot of people reported read problems with their PX-708A ...

..actually this is not a problem, all Plextor drives are very sensitive when it comes to reading. Physical and geometry problems of the disc may be neglected by a LiteOn drive for example, while you will get a read error with a Plextor. Of course, this behavior might be considered as a problematic for the user who needs his disc read.
But is it a problem when you are scanning for read errors?

The near-perfect read device should be some kind of tolerant towards any disc error you throw at it ... since we all know what kind of severe defects can occur on a disc, it is in the user's interest to get the best possible read and error correction performance.

(in reply to Tony Veglis)

Of course it should be tolerant and that's the way it is in general, especially in case of stand alone players. Otherwise we would not be able to use a reader. But I thought we were talking about disc scans for writing quality. Wouldn't you prefer a "picky" reader to evaluate the quality of a recorded disc?

(in reply to JeanLuc)

quote:

ORIGINAL: Tony Veglis
Wouldn't you prefer a "picky" reader to evaluate the quality of a recorded disc?

Now I get your point ... Of course, I would definitely prefer a "picky" reader (or even better - a calibrated one) for disc scans.

After all, my LiteOn 411S had to go because of it's lack of pickyness ...

(in reply to Tony Veglis)

quote:

ORIGINAL: JeanLuc

quote:

ORIGINAL: Tony Veglis
Wouldn't you prefer a "picky" reader to evaluate the quality of a recorded disc?

Now I get your point ... Of course, I would definitely prefer a "picky" reader (or even better - a calibrated one) for disc scans.

After all, my LiteOn 411S had to go because of it's lack of pickyness ...

I went into an electronics store a while back, and told them I wanted the pickiest DVD player they had. They could not even begin to fathom WHY I would ever want a picky DVD player, but they did the best they could in recommending a Sony stand alone player

I ended up buying a Samsung because it looked nice, it sure isn't picky though... I'll buy another one later when I have some low quality discs along so as to test for pickiness

(in reply to JeanLuc)