PoweRec and Burn Speed Testing

I have acquired a Plextor Premium CD burner for use in long-term archiving of important data and collected music. My emphasis is on data accuracy and longevity, not on time savings.

I ran a preliminary series of burn-speed tests on various media, hoping to deduce the proper speeds for lowest errors. I quickly learned that Plextor’s PoweRec feature makes this task a bit more complicated than I am used to. I have studied Plextor’s white papers, talked to their tech line, and reviewed various posts in this forum. I still badly need help.

Although I will probably want to use PoweRec when eventually burning my archives, I would like to turn it off while testing my media (MAM-A and TY). I go into Plextools to turn it off, but it won’t stay off. I use the Prassi-engine burner ONES for writing my CDs. It does not offer an option for disabling PoweRec. Consequently, PoweRec makes speed adjustments during my test burns, greatly complicating my media-evaluation tests.

Has anyone discovered a way to temporarily disable PoweRec so that straightforward burn-speed tests can be run? If not, is there some other approach to determining what burn speed I should set in my burning software, in order to achieve lowest errors?

I hesitate to simply set the speed at “Max” and let PoweRec decide the speed on its own. Plextor says PoweRec allows you to burn as fast as possible while maintaining “good” quality. I myself would like to get the “highest” quality, and I don’t care if it takes longer to get it.

One final question on Plextor/Plextools burn-speed testing:
Plextools offers me a max error scan speed of 10-24X CAV. Other drives I have owned offered 52X scan rates. Many people have recommended testing at the highest available rate (to really discriminate). Why does Plextor limit scanning to 24X?

Many thanks for any insight on any of these issues. I have already test burned a couple dozen discs, and I am still very unsure of how to choose my burn speeds for this new piece of equipment.

You could also try Nero Burning Rom, as you can turn off PowerRec. I don’t know if it stays off though?

I also let PowerRec control the burnspeed. I think it works very good, if you can accept not getting full speed :slight_smile:

Moef

u must keep plextools running during burning.if u close it the drive will be reset

Why?

What does a burn at maximum speed without adaptive adjusting tell you about the media quality? Nothing! Because if the drive selects the wrong laser power the media is not at fault for failing to record properly! Also burning at maximum speed does not necessarily say something about media quality, but rather if the drive is capable to follow the pregroove properly and focus correctly on the surface, which becomes increasingly difficult the higher the speed.

Now, for example, if the media is certified for 52x and the Premium has a 52x strategy but consistently decides to slow to 40x i’d consider 32x to be the maximum ‘safe’ speed.

Easy. Burn different discs of the same brand at different max. speeds, watch for slowdowns an compare the scans.

IMHO this is a nice method for checking a single disk:

http://club.cdfreaks.com/showpost.php?p=988175&postcount=68
http://club.cdfreaks.com/showpost.php?p=988177&postcount=69

Good thinking. My advice would be stay <=20x for top quality.

Speed works against accuracy. And the argument of low error rates (at low accuracy) at 52x scanning versus the accurate numer of errors (at high accuracy) is a bad one.

You think the drives are not able to add a few numbers at higher speeds?

While the PX Premium indeed has a firmware limit of 24x speed for scanning, PX-712 and newer can scan as fast as they can read (48x CD, 40x CD-RW)

Thanks to everyone who has responded so far. Each response has been helpful.

hwp, your example of using multisession burns to compare speeds on a single disc is a great idea. I can’t believe I didn’t think of that. I’ve been trashing piles of discs by testing DAO. BTW, your responses triggered a couple of new questions, which I hope you can comment on:

  • You mentioned that testing without PoweRec means testing without optimized laser power. Does that mean that disabling PoweRec also disables running OPC? I thought that PoweRec worried about speed, and that running OPC happens regardless of PoweRec status. I’ve read the white papers, etc. on PoweRec, but I guess I still don’t understand it. Perhaps you can clarify for me??

  • I’m also under the impression that PoweRec makes frequent pauses in the burn in order to test write quality, then uses BurnProof linking technology to sew the pieces together. Doesn’t this sort of thing introduce errors? Or does that go back to the old days of Z-CLV horror stories?

I guess I’m still pretty much a newbie, so I appreciate your patience!

You generally do not want to do a quality scan much higher than 24x. Faster than that and you bring all sorts of things into the equation for error checking: disc flatness or eccentricity, internal functioning of the drive spindle motor and any vibration that might be transferred to the disc surface, aerodynamics of the disc spinning at 10K RPM causing flutter, focus and tracking ability of the drive, etc. You want your disc check to be on disc quality, not on drive quality at that point.

Regarding MAM-A archival, I found 16x to get the best quality burn on 52x rated media. Above that and the error rate climbed to the point the discs would fail the testing.

The drive does OPC to determine the best laser power and then ROPC to monitor the laser power “signature” during the write, compare it to the OPC stored value, and increase or decrease as necessary. The drive uses PR to monitor the DATA and checks for error rate by stopping the burn, comparing the data, and then increasing speed if the error rate is low. PoweRec gives you that extra monitoring you need to get the best possible write. After all, as you say, it is quality, not recording time, that is most important to you.

PoweRec is Plextors implementation of a running OPC. More specifically running OPC is part of PoweRec

From http://www.plextor.com/english/news/pdfs/powerecwhitepaper-4.pdf:
“OPC and Running OPC work pretty well at successfully burning on a wide variety of discs. But these tests are only used for determining laser power; they don’t monitor the writing quality.
So Plextor developed a technology called PoweRec (for “Plextor Optimized Writing Error Reduction Control”), which monitors the quality of the data as it is written to the disc. PoweRec is used in conjunction with OPC to determine the disc’s vendor and the complete write strategy—including writing speeds and optimum laser power values—for the specific disc being recorded.”

For more Info in ®OPC: http://www.plextor.com/english/news/opc.html

Basically OPC controls laser power and PoweRec controls laser power plus speed. So turning off PoweRec means turning off laser and speed control, IMHO.

A ‘running’ OPC does not pause. The reflected light from the burning laser is analised in real time (continuously or in intervals). AFAIK a burn proof instance only happens when PoweRec decides it needs to change the speed. The drive needs to slow or raise and then stabilize the new speed before burning can continue. This takes time and therefore makes it necessary to suspend writing for a moment.

You can observe this behaviour when using Plextools for burning. If the drive didn’t slow down Plextools will report 0 BP instances, despite the fact that ROPC was working. However as soon as a slowdown occurs at least one BP instance is reported at the end of the burn.

Basically you might want to avoid BP instances, since they might be just another cause for errors. In real life the technology is very mature (the ‘gap’ that BP produces has become very small) and i’ve never heard of a disk failing later on because of BP occurences.

Many thanks, hwp and bob11879 - -

I’ll be much more comfortable in establishing my burn SOP now that you’ve clarified these issues for me.

Sounds like I’ll want to keep PoweRec “on” while making actual data burns, since its advantages far outweigh any potential drawbacks. And if I establish by optimum burn speed properly, PoweRec won’t have to make any speed corrections anyway.

Looks like 16X may be the optimum speed for my media/drive combination, too. I used to burn everything at the lowest possible speed (which is 4X for this drive). But these tests I’ve been running show that I sometimes get higher BLER at 4X than I do at 8 or 16.

Now if only I had a clue as to how to interpret jitter …

Again, thanks for being so kind as to give such detailed advice.

Just remember that Plextools does not show the absolute value of the Jitter in Percent but shows the change in the absolute value (whether is raises or falls).

You cannot compare two scans of different media in absolute terms, because Plextools does not say what the displayed curve of changes bases on. Thus if scan one shows a line that is higher in the graph than in scan two, this does not necessarily mean the Jitter to be higher than in scan one, since you dont’ know the base of that value.

That’s why the multisession-method mentioned above is ingenious. While not giving you the absolute values, it shows the change in Jitter for the worse or better at different speeds.

Yes, that multisession idea seems to offer a lot of advantages. I sure appreciated your pointing it out to me. I hope to try it out this weekend, and report back on what I learn.

Thanks again for your constructive help.

You can see those absolute jitter values if you use PxScan/PxViewto perform the jitter scan; those values cannot be directly translated to a jitter percentage, but they can be compared between discs!

Yes, it is rather clever! :iagree:

Thanks, DrageMester.

I had come across articles on PxScan, but it looked like it might be a bit “over my head.” Perhaps I should give it a try, and see how usable and meaningful it is in comparison with PlexTools.

I’m looking for the basic tools needed to:

(a) Decide which speed to burn my MAM-A (or occasionally TY) CD-R data and audio discs in order to get the lowest errors (and, presumably, greatest longevity)

(b) Occasionally test my archive discs to determine how their integrity is holding up.

Everyone’s suggestions in this forum have been very helpful.
Thanks for responding.

Yikes - - another issue has arisen:

I burn my data discs using Mode 1 (max error detection/correction).
I also burn a lot of playable audio discs (lower error handling).

Will the optimum burn speed for Mode 1 burning likely be the same as for audio-disc burning? Or will I need to do speed-optimization testing for each of these two modes?

Since the additional checksum data is burnt on the disc the testing method should be valid for both modes.

BTW: I put up some scanning results with the multisession method: http://club.cdfreaks.com/showthread.php?t=136562&page=6#post1259835

I am not an expert, so I made my test “by ear” (talking about audio CDs of course). And here you have my subjetive conclusions: (Recorder is a PX-716A)
Media: TY
Recording speed: 8x
I didn’t understand why 8x is better than 4x… but I’m glad hwp post confirms may be I’m not totally insane.

Thanks, hwp, for the new multi-session scan-test results. I’ve started running some of these myself, on a variety of media. As soon as I identify the most-useful ones, I’ll post them for your interpretation.

Meanwhile, I wonder if you could comment on the scans that you posted -the Sony Type 5 and the TY (Plextor) Type1. Based on your test results, what burn speed(s) would you deduce to be the optimum for the Sony and for the TY in your 712a?

Do you base your choice strictly on which speed produces the lowest errors, or do you base it on some combination of error level and jitter behavior? I have seen tons of scan-test results on-line, but I’m having a very frustrating time trying to find out how to interpret these scans to decide upon a best burn speed. Plextor has a brief tutorial in their PlexTools guide, but it leaves me bewildered.

My main purpose in this thread is to learn how to choose an optimum burn speed that will give my archives (data and audio) the greatest possible longevity. I think you’ve almost gotten me there, but I still need to learn how to interpret these graphs.

Many thanks for your continuing interest and support.

I let my Premium burn data only at 24x max. I do my audio burns at 16x and have seen no increase in quality compared to 8x or 4x.
If it is for someone else, I occasionally increase the speed to 32x :smiley: (The results are fine though)
With these settings all my results are excellent and to be honest, this is quick enough for me.

Regards,
weaker

Sony: 8x Speed seems optimal. Jitter is low and Beta is closest to 0. For comparison, these are regular burns of the same Sony (ignore the Jitter Spikes, they are an error of Plextools) in the 716 http://club.cdfreaks.com/showpost.php?p=982084&postcount=9 and the 712 http://club.cdfreaks.com/showpost.php?p=982337&postcount=22 and in a Premium http://club.cdfreaks.com/showpost.php?p=1111272&postcount=117

Yuden: 32x Speed seems optimal. Jitter rises only a little compared to slower speeds and Beta is a lot better than at slower speeds. For comparison the same Yuden in a 716 http://club.cdfreaks.com/showpost.php?p=1132079&postcount=122 and a Premium http://club.cdfreaks.com/showpost.php?p=1132078&postcount=121

You always have to see the whole picture. Here are some rules:

C1: Allowable maximum 220, but good burns stay way below 50. Both examples are very good burns in this regard
C2: Should be 0. Less critical on data discs than on audio.
CU: Must be 0.

Beta: Should remain between ±0.08 for audio and ±0.02 for data. Should be a straight level line without jumps for best readability. However there seems to be a lot of ‘overhead’ allowed.
Jitter: Should be a straight level line without jumps for best readability. Should not rise toward the outside of the disk.

Well, thanks to everyone for all those suggestions and guidelines. I’d like to recap what I’ve learned here and what I’ve read elsewhere, to see if it makes sense to the other people in this thread/forum. Your criticisms are very much welcomed, as I am about to set off burning a lot of data, and I’d like to get off on the right foot. So here’s my “take”:

The objective of the burn speed tests is to find the speed that gives the lowest number of errors (BLER) across the disc. Uncorrectable errors (CU) are unacceptable, and C2 errors are highly undesirable, since - over time - they may soon result in uncorrectable errors. So goal number one is getting zero CU and zero C2. I have found this to be fairly easy if I use good-quality media. Goal number two is to get the total BLER (in this case, the C1) as low as possible. I do that by making test burns at various speeds, and checking the results.

Now we come to jitter and beta tests. As I understand it, jitter is a measure of the variation in the lengths of the pit/land patterns. Excessive variation can generate C1/C2 errors. Unfortunately, Plextools does not give an absolute measure of jitter, but only shows its variation with time. Therefore, the jitter results must be interpreted together with the C1/C2 test results. If the C1/C2 are very low, than the jitter must be very low, since high jitter causes C1/C2. If C1/C2 is high, and if it shows a similar time pattern to the jitter, than jitter can be fingered as the cause of the C1/C2.

Beta is an indicator of the sharpness of the pit/land transitions. The read laser may adjust its power during reading in order to better sense these transitions. These adjustments show up as steps in the beta curve. Large adjustments are undesirable, as they indicate the reader is being challenged to read without errors. For audio (Red Book), we want beta < +/- 0.08, and for data, < +/- 0.02. If C1/C2 is excessive, and if it follows the steps in beta, then beta is the likely cause.

So it seems that the jitter and beta tests are really tests that tell me WHY there may be excessive errors. They are not ADDITIONAL errors of some sort. If C1/C2 are acceptably low, than things are OK. If C1/C2 are high, then the jitter/beta tests can help me understand why.

I have now made multisession test burns on a MAM-A gold 2X disc and on a TY (Fuji) 52X disc. Plextools C1/C2 and jitter/beta test results are attached to this post. The MAM-A apppears has its minimum errors at 8X writing, although 16X is pretty close. Jitter is flat across each zone and beta is very low in each zone. Now, jitter APPEARS higher with each successive increase in burn speed, but I assume this is a result of Plextools showing it in unitless fashion. If jitter actually got worse and worse with each speed increase, why would the lowest errors be at 8X and 16X?

For the TY disc, the errors are a bit higher, but are still nice and low. There isn’t much different among 8X, 16X, and 20X. Again, the jitter curve shows steps with each speed increase, but these do not correspond to gross changes in error level, so presumably they are again only relative.

Finally, I have noticed during some full-disc test burns that the very outer part (last few minutes) of a disc can be more susceptible to errors than the rest of the disc, even when writing in CLV. I even generated C2 at the extreme edge of MAM-A gold when buring at 4X on my old Lite-On 5238S. So it seems advisable to always run some full-disc test burns before deciding on my standard burn speeds for new media. And it seems like a good idea to avoid burning the outer minute or two of a disc, if possible.

I’d really welcome some constructive criticism of my above analysis. I’m sure there are plenty of “holes” in it, but it’s my best effort at understanding this idea of how to choose a burn speed.

Thanks!