Is a good KProbe result a guarantee?

vbimport

#1

I am getting excellent burns on my 401@811 using Ritek G04 - according to KProbe no errors above 50 PI and PO 1-2. Does this mean the DVD itself will be sure to be glitch-free?


#2

I generally also rely on what I call the “16x torture test”… get a hacked drive that can read burned discs at 16x CAV (LiteOn -ROMs, LiteOn combos, or some Toshiba -ROMs), and see how smooth that reading curve in CD-DVD Speed turns out.


#3

Hi,

I do the kprobe, and then a cdspeed surface scan in my laptop´s DVD, (a Matsushita 745, which is quite picky with media). With this two I can be almost 100% sure the disc will play OK in all my DVD standalones and other accessible readers…

Note that once you have done this a few times and if not changing media/drive, then KPROBE will suffice since you will notice by looking at the results when the burn was ‘ok’ for that media/drive. (i.e in my case (811s) my +R verbatims 4x write at a PI average of 20, and PO <0.02. When I see results worst than this it usually means troubles… but my TY 01´s get even smaller PIs…)

Regards
FTC


#4

I was intrigued by code65536s “16x torture test” so I patched my 166S to read at 16 speed. I tried two discs with good kprobe results (PI < 8 & PO < 2) and one adeqaute kprobes (PI < 200 & PO < 15).

Of the two good discs, one to right to the end at 16x before slowing while the other started slowing down at 15x.

The adequate disc had a few wobbles in the middle but read all the way to the end of the disc at full speed.

@code65536

Could I then assume that getting a clean transfer from start to finish (at 16x) is the exception rather than the norm, even for good media?

-BigJas


#5

A disc that goes smoothly from start to finish is rare. A lot of times, once the speed goes beyond 16x, problems start occurring. So when doing the “torture” test, you have to be a bit subjective. I’m attaching three reading curves… each of these were done on a full disc (100%) so that at the end, it actually goes beyond 16x…

Scan #1: Perfect. Almost hits 16.4 at the end! There are little dips along the way, but these are very minor and can be ignored. If you don’t hear the motor ever slowing down, then you know that a dip can be safely ignored.

Scan #2: Also perfect. The only problem is that it started hitting problems after the 16x mark, but given how fast 16x is and how the rest of the disc was scanned flawlessly, this goes down in my book as a great result.

Scan #3: This is an example of a disc with a problematic area. As you can see, the disc scanned mostly fine, including that final area where it peaked above 16x. But there is that area towards the beginning where the motor noticibly slowed down and thrashed around a bit. The disc was still readable, but you can see that there was a pretty sharp and pretty wide dip there, indicating some real problems. Indeed, that exact area of the disc did have higher errors in the KP scan. In addition to the deep and wide shape of the dip, the fact that it took place at a lower-speed area makes it an unforgivable defect in my opinion.

Generally, you have to be a bit subjective and a bit forgiving. Knowing that burnt media was designed only to be read back at 8x, for them to read back nicely at 16x really means a lot.


#6

Thanks for the info. You’re a useful guy/girl (delete as appropriate :wink: ) to have around.

I really should proof read my posts better. It’s rather embarrassing to look back and see the gibberish that can result from a few mistakes :slight_smile:

-BigJas


#7

> I am getting excellent burns on my 401@811 using Ritek
> G04 - according to KProbe no errors above 50 PI and PO 1-2.
> Does this mean the DVD itself will be sure to be glitch-free?

glitch-free as in defect-free, yes. It doesn’t guarantee that any
other player will read that disc, but there are very good chances.
However tests with a patched firmware say nothing about the disc,
all you are torturing here is your poor drive.


#8

You’re right; in the absense of expensive devices like CATS scanners, this is just a heuristic. But it’s one that seems to work well for people.


#9

I’m not talking about CATS versus software tools. What I’m saying is that
a CDSpeed test at 16x on a modified drive will tell nothing more about the
disc than a low speed Kprobe scan (on the contrary, it can be misleading).
Btw the media forum is a better place to ask such questions.


#10

There have been cases where KP scans would turn out nicely but the disc has trouble reading elsewhere. I guess I like to think of this as a “second opinion”. And doing it at 16x allows it to pick up problematic areas that might not otherwise be picked up at 8x (I’ve had 8x reads that were smooth but when jacked up to 16x, certain areas developed problems, and those areas happened to also correspond to higher error regions found by KP).

Btw the media forum is a better place to ask such questions.

Good point! Thread moved.


#11

A second opinion indeed adds something to the original test, but not
when you get it from a patched drive forced to run at 16x : with this
you only increase the impact of the drive itself on the measures,
while you are interested only in the disc. A second Kprobe scan on
another drive, at a standardly supported speed, would add more valuable
information to the first test.


#12

I’m on the fence on this topic, I can see benefits and shortcomings of the transfer rate test.
In the absense of high measured PI/PO, a disc that has trouble at full-speed reading may well have other issues. I refer to discussions on ADER and jitter.
However I also agree with Spath, I think, that a disc with high PI/PO that is able to read at 16x on another drive is still highly suspect. Unless you are running both tests in the same drive, the “Second opinion” is of questionable value.

I’ve yet to see a well-burned, quality disc that does not pass all these tests in most drives, but we’re talking about the not-so-well burned discs here, which of course is often the situation that many users find themselves in.
ROM drives can slow for a variety of reasons, high read-errors is just one of them. Some will point to jitter as a possible cause, but I have yet to see a disc with high jitter that does not also have higher PI/PO.

My vote still lies with high ADER values as the cause for difficult reading in the absense of high PI/PO. But lets also remember that a conbination of all 3 (or 2) things may well be just as likely.
But let me repeat that a disc that has high PI/PO readings is not “good” just because it reads at 16x in a ROM drive. The fact that it does just makes you feel better. :wink:

BTW, I’m thinking of merging this with the Kprobe thread. I’ll sleep on it…


#13

ive seen many a good disks not pass a 16x read test at the end…i really see little need to run a speed check on a dvd at 16x as many will fail and still play or read excellent on all my home player and dvdrom drives. running the pi/po (pie/pif) tests along with a speed check on the SAME drive is the best way to test a burn imho. My 812 does a great job at telling me a good burn running both tests on it and my max speed is 12x read which is plenty fast enough for speed testing. And yes as far as jitter ive never seen it get much higher than 15% for a good burn other than a bad disk which has high po (pif) anyways so jitter really imho coorisponds with error rates so i see little need to test it.


#14

ADER has nothing to do with reading problems and I wish people who
distribute tools to measure internal drive parameters would also explain
what these parameters actually mean.