BLER & ADER: A Tale of Two Coasters

vbimport

#1

The Story

Once upon a time… wait, wrong story format. I was playing around with some write strategy changes. I have a spindle of RITEKR01 discs rated for 2.4x that I have yet to really successfully burn at 8x. I was also playing around recently with improving my RICOHJPNR01 burn quality by having my burner use the RICOHJPNR02 write strategy when burning RICOHJPNR01 discs. The results of this swap of the Ricoh strategies was fantastic, so I decided to do the same for my RITEKR01 strategy–I made it so that my burner will burn RITEKR01 discs with the RITEKR03 strategy. And the results were wonderful! Low PI and PO. I happily popped my newly 8x-burnt RITEKR01 into my combo drive to do a reading scan. And much to my shock, not only did the drive start thrashing at the end, I got an unrecoverable read error! Highly unusual, as my successful RITEKR01 burns (at 6x) read smoothly on my combo. :confused: What went wrong?..

Since every RITEKR01 that I’ve ever burned at 8x have coastered, despite low PI/PO, I started to think that there must be something else at play in dictating readability. What about ADER?

Having Fun

So I did something fun; I cleared out my EEPROM’s power calibration data. (Please don’t try this at home :p) And I burned a RICOHJPNR01 disc with this really messed up EEPROM. Needless to say, I got extremely high PI/PO errors, and the disc was a bona fide coaster, but interestingly, I got very low ADER errors when I later scanned the disc using the ADER test.

Interestingly, the RITEKR01 also had very low ADER error rates when I scanned it… except at the end, near the place where the unrecoverable error occurred. There, the ADER rate jumped.

My Conclusions

Although this has already been said in the ADER/ATER thread, there is more that goes into quality than just PI/PO BLER tests. You have two factors at play here: the power of the laser and whether or not things are being written at the right place…

Coaster #1: RITEKR01 - This disc coastered because of a jump in the ADER rate. Causes of an ADER-related problem: poor precision of the laser’s tracking, resulting either from poor hardware (in which case, ADER rates will be high for all discs) or from discs that are physically unsuitable for high speed burning (the grooves are not cut well enough, there’s more warping towards the edges, etc.)… however, the write strategy was good, the power calibration was good, and that’s why PI/PO remained low for the most part.

Coaster #2: RICOHJPNR01 - This disc coastered because of (deliberate) improper power calibration. This could be caused by a number of factors: poor writing strategy (since the strat controls the amount of laser power used), poor drive calibration (if the factory didn’t quite get the EEPROM calibration right when the drive was shipped… or if you purposefully nuke your EEPROM, as I did), or the disc’s dye has problems (perhaps the write strat was designed for one type of dye, and then the manufacturer suddenly decides to switch to a different dye type without changing the media code). In this case, bits were being written at the right place (because the RICOHJPNR01 discs have better grooves or whatever and was simply better suited physically for higher speeds), but the power being applied was wrong, which ultimately coasters the disc.

And another thing…

Something to add to all this is that if you have good media that burns with really high cliff-like PI/PO errors, that’s probably indicative of power calibration problems, which means that a firmware update (with a newer, better write strategy) could solve your problem.

Alternatively, if you have a coastered disc, and you run an ADER scan on it, and it turns up with very low numbers, then you know that the disc coastered because of improper power calibration (which can be more easily fixed, as a new firmware could do the trick) and not because of poor hardware precision (which could prove to be harder to rectify)

And now, for some pictures… :wink:


#2

As a reference point, here is what a well-burned RITEKR01 (6x) looks like when read by my combo… to rule out possible problems with the reader…



#3

Now, for Coaster #1, the RITEKR01…





#4

And Coaster #2, the RICOHJPNR01 burned with the deliberately sabotaged EEPROM





#5

There are other facters, possibilities too. A drive may have excellent capabilities on good media, but fail to adequately compensate for crappy media. Low ADER is the result of both good media and good hardware.
And then there’s jitter, which in my mind is somewhere in between PI/PO measurements and ADER, and can inter-act with both.

Also, read ADER tests are not recommended, just the write-ADER test is considered to be a meaningful test. But if the media is sub-standard, the ADER test will reveal nothing about the hardware.

It’s assumed that high ADER rates can accompany high PI/PO, but low PI/PO does not always accompany low ADER. To put it less obtusely, you can have low ADER and high PI/PO. I assume it’s also possible to have low PI/PO and high Jitter. Whether high jitter can exist without high ADER is a question left to be answered IMHO.

So I guess my tentative opinion is that one does not really need jitter measurement if you have ADER and PI/PO measurement.
I have felt for a long time that most, if not all, of the reports of widely varying PI/PO scans were due to poor tracking and servo error, the result of poor media or poor hardware or both.


#6

BTW, I take exception to the idea that because a ROM drive balks at reading the disc at 16x, that it is a “coaster”.


#7

A quasi-coaster. :wink: But an unrecoverable error (and not just slowing down) is a far cry from a smooth read (esp. when most discs that I have read smoothly at 16x)… I agree, it is a bit of a stretch; if I could’ve found a more extreme example, I would’ve used it, but I didn’t have one. :confused:


#8

It’s actually only a very small percentage of burned dicscs that will read at 16x. (But failed reads is of course not the same thing as slower reading). Most ROM drives will slow dramatically, and never re-gain their speed, when they encounter read-errors. In most cases, reading such a disc at 8x will be quicker than reading at 16x. Perhaps the drive makers have just cause for locking read speeds on recordable and DL media. :iagree:


#9

i would agree too thats why they put readlocks on the drives! im not a big fan of rip-unlocking myself have gotten alot more errors too on scratched media with drives that have it. thats why i use stock firmware on my liteon 48161h and rip with it :wink: yes it may take longer but i get very good rips from it even with scratched media.etc. .


#10

As rdgrimes says, YMMV. :wink: None of my burned discs are scratched and most are well-burned, so the 16x works well. :wink: Removing speed limits should be used only by those who have good media.