Ultimate Testing of
Recordable DVD Media Discs

by Andrey Kuznetcov 04/14/2005 | 08:08 PM (Original dokument)

What are the major criteria for your decision when you shop for blank recordable DVD discs? Is it the brand name of the manufacturer? Or the maximum claimed write speed? Or the price per piece? Well, we decided to check out over 40 different discs available in the market today to see how good they are. Hopefully, this roundup will help you make the right choice.

In some ideal world there wouldn't be any problems with data storage media at all, but ours is a harsh and cruel reality where optical drives sometimes have difficulties writing discs or reading them afterwards. These problems may come from various causes. For example, the optical drive itself may be defective at performing read/write operations. Then, you may have encountered such a situation yourself when the drive just ignores the disc you've inserted into it.

In many cases this problem can be solved by re-flashing the drive's firmware, since this procedure updates the database with information about different media and operational modes suitable for different discs. But the firmware update doesn't always work, we should confess. To secure yourself against purchasing a bad device, you should read reviews of optical drives before the purchase. In this article, however, we are going to inspect the other side of such conflicts, i.e. the media (the programs you use and the whole configuration of your computer may be intervening factors, too, but of less importance).

So why do we touch upon the problem of media in this article? Because however good you optical drive may be, there will always be blanks you don't have the expected burn quality with. Of course, it's possible that you've got incompatibility of a particular drive with a particular disc, but we are interested in answering the general question of which media available now on the market are preferable from the standpoint of quality. Of course, the old rule that you can be on the safe side sticking to media from renowned brands holds true, but there are many DVD discs from obscure companies that offer a comparable quality at a much lower price.

The problem of choice of media becomes the more complex now because many companies that have never been engaged in this business have started to promote their own brands of discs manufactured by other companies under OEM contracts. They can vary greatly in quality, of course, and it's better to test them in practice to see what's better. We should remind you that there are much fewer real manufacturers of DVD blanks than there are companies whose brands and names these blanks are selling under. It is not impossible to spend different money on different media only to find them fully identical to each other under closer inspection. So, we have tried to free you from the routine and tiresome work of finding the best write-once and rewritable DVD blanks by performing such tests in our labs.

Of course, it's impossible to test everything, but we did our best and are now ready to share the results with you.



Testbed and Methods

We took a Lite-On SOHW-1653S (firmware revision CS09) as our etalon of an optical drive. We made this choice basing on the fact that drives from Lite-On are widely available on the market, under Lite-On's own brand as well as under other company's badges. For example, the SOHW-1653S is in fact identical to such models as Lite-On SOHW-1633S, Sony DW-U22A, and Teac DV-W516A. Another reason for our choosing this Lite-On for this test session was the compatibility of this drive with Nero CD-DVD Speed. The KProbe utility that we use for scanning the surface of the written disc also supports Lite-On's drives. Of course, high-quality burning comes as the result of a harmonious combination of a drive and a disc, but we will be evaluating the quality of the tested discs basing on their performance in one particular drive due to the above-explained reasons. We use two programs to scan the written DVDs to obtain objective results and also to understand their operation better with more media and to ultimately answer the question which program is more efficient and correct.

So, we copied a DVD Video movie from its ISO image on the hard disk drive to the tested disc and scanned the disc after that. The configuration of our computer was like follows:

We attached the optical drive to the second IDE channel as 'Master'.

The following software was used in the tests:

The DVD-RW/+RW discs were recorded at the maximum speed they are rated for by their manufacturers. If this information was unavailable, we determined it practically, finding the maximum possible speed. The subsequent scanning of the written discs was performed at a constant speed of 4x.


DVD Quality Criteria

Before getting to the tests proper, we want to illumine you on some theoretical aspects concerned with evaluating the quality of DVD discs. We base our judgments about the quality on the data we receive by scanning the recording with the two above-mentioned programs (we should say it first that the numbers may be different with another optical drive). CD-DVD Speed and KProbe evaluate the quality of DVD discs by counting up the number of PI errors and PI failures.

The ECMA standards for DVD-R/RW and DVD+R/RW media say that the total number of PI errors in 8 subsequent ECC blocks should not exceed 280. This is the first limiting value we will base our judgments upon. A PI error is a row in an ECC block which contains at least one erroneous byte. A row in its turn consists of 182 bytes in which the last ten bytes contain Parity Inner information. Each ECC block contains 208 rows where 16 last rows contain Parity Outer information. An ECC block should not contain more than four irrecoverable PI errors (an irrecoverable PI error is referred to as PI failure by KProbe and CD-DVD Speed).

Thus, we consider those DVD discs as quality media that have no more than 280 PI errors and 4 PI failures per one ECC block. The errors of the second type, the irrecoverable ones, are the worst, of course.



Testing Participants

Creation DVD+R 4x

  

The first of the two Creation discs we got for our tests comes to market in the 'box-less' way. The real manufacturer of this disc is Interaxia AG, as you can see from the screenshot of the DVD Identifier utility.

By the way, the information about the manufacturer is stored in the ADIP zone (Address In Pre-groove) on DVD+R/RW discs and in the LPP zone (Land Pre-Pits) on DVD-R/RW discs.

  

We have no desire to comment on this. The result is utterly disappointing. It starts out quite well, but ends in a total failure. The quality of the disc comes to naught towards the end of the recording - all the norms are violated over and over again. Purchasing this disc would be the same as throwing this money away (but don't forget about the psychological shock you're likely to suffer with such media!)


Creation DVD-R 4x

  

The second disc from Creation is also manufactured by Interaxia AG. Unfortunately, we couldn't test it fully - the disc proved to be incompatible with the Lite-On drive. Nero Burning ROM would issue an error message as soon as we tried to burn this blank. Of course, it doesn't mean this disc is going to behave like that in other drives. It's possible that there's 'mutual antipathy' between the given disc and drive, which may vanish with the next update of the drive's firmware, but you should be careful nevertheless.



Digitex DVD+RW 4x

  

As you can see from the screenshot, the rewritable DVD+RW from Digitex is manufactured by Optodisc Technology Corporation. Maybe somewhat off the topic, the Taiwanese Optodisc, founded in 2000, equals its name to 'Optimum, Professional, Technologies, Organized, Disciplined, Innovative, Successful, Creative' which are the key concepts of the company's philosophy.

  

The two test programs are unanimous in their evaluation of the quality of this disc, reporting the same maximum peaks of PI errors and failures. The former parameter is acceptable, but the latter is two times above the critical value of 4 failures. The total number of PI failures is rather high, too. Considering this, it's not impossible that you'll find the recorded disc unreadable.


Digitex DVD-RW 4x

  

This disc is also manufactured by Optodisc, according to the information stored on the disc itself.

  

The scanning of the recording layer of the disc brings almost the same results: both programs have come up with identical maximums of errors of either type. So, we're pleased to note that this disc fully meets the requirements. What's more, the maximum of PI failures coincides with the allowable maximum, but the maximum of PI errors stops far from the limit of 280 errors. You are unlikely to have any troubles using such media.



Digitex DVD+R 8x

  

To our regret, we can't say anything positive about this one. Another disc manufactured by Optodisc proved to be indigestible by our test drive. The drive did identify the inserted disc and everything was normal until Nero Burning ROM gave out an error message that it couldn't perform the burning. We took another sample of the same disc, but without success. It's hard to name the reasons for this failure, but maybe the next firmware update will help?


Digitex DVD-R 8x

  

The last disc from Digitex in this review is, against our expectations, a product of such a renowned manufacturer as Taiyo Yuden Co. Ltd.

  

The quality check brings disturbing results. The maximum of recoverable PI errors is within the norm, but instead of the allowable maximum of four PI failures we have as many as twenty here! You may note, however, that the quality problem persists on the first third of the disc, and the maximum of PI failures doesn't exceed two elsewhere. So, it's possible that other samples of this disc are going to show a better performance.



Dysan DVD-R 4x

  

The DVD-R disc from Dysan is in fact a product of CMC Magnetics.

  

Both programs agree that there're no problems with the quality of the written disc. The maximums of errors are within the norm, especially the PI failures. The total of PI failures is small, too. This disc shouldn't provoke any problems in use.


Fujifilm DVD+RW 4x

  

The disc selling by Fuji Magnetics is manufactured by Ricoh Co. Ltd., as you can see from the screenshot above.

  

The test programs agree the disc is almost perfect. We just mean the number of errors is very small, because there is no such thing as an absolutely errorless optical disc. Here, the maximums of PI errors and failures are fully compliant with the industry regulations and are even much lower than the limits. This is especially true for PI errors. The quality of the surface of the disc is uniform, too. Considering these points, the disc can be recommended for your use.



Fujifilm DVD-RW 2x

  

The next disc from Fuji proved to be made by the popular manufacturer Mitsubishi Chemical Corp.

  

As you can see from the two screenshots above, there can be no complaints about the quality of the disc. On the contrary, the maximum of PI errors is far below the acceptable limit. The PI failures are evenly distributed along the surface of the disc, which is on indication of stability of the recording layer.

If you need a high-quality disc, this one is for you. The only downside of this medium is its rather low speed. 2x is slow by today's standards.


Fujifilm DVD-R 4x

  

Prodisc Technology Inc. is the real manufacturer of this DVD-R 4x blank.

  

The test programs give out satisfactory results. The maximums of PI errors and failures are much below the limit. The PI diagram shows that the burn quality somewhat worsens towards the end of the disc. The total number of errors is small, too. So, this disc is a good candidate for purchase. You shouldn't have any problems recording such media.



Imation DVD+RW 4x

  

The rewritable disc from Imation is manufactured by Moser Baer India Ltd.

  

We have no complaints about the quality of the disc. The maximums of PI errors and PI failures are low. The totals of these errors are low, too. The errors are evenly distributed along the disc, which is an indication of a well-polished-off manufacturing process.

This medium can surely compete with major brands; we recommend it for all potential users.


Imation DVD-RW 2x

  

Another rewritable disc with the Imation badge is manufactured by Optodisc Technology Corp.

  

The scanning of the disc doesn't yield as excellent results as in the previous case, but they are anyway good enough for the disc to be considered appropriate. This is yet another worth-your-money disc the users shouldn't have any problems with.



Imation DVD+R 8x

  

The 8x blank of the DVD+R format is a product of Ricoh Co. Ltd.

  

Both test programs agree that the quality of the written disc meets the requirements, with errors of both categories. The level of PI errors is growing up somewhat to the end of the written area, but anyway remains within the acceptable range. Without doubt, this disc also deserves your attention.


Imation DVD+R 4x

  

Another DVD+R disc from Imation has no indication of the supported burn speeds on itself or on the paper insert in the plastic box. Most often such silence means the manufacturer has something to conceal about the product, particularly its not very high speed. DVD Identifier pointed at Ricoh Co. Ltd. as the manufacturer of the disc and revealed that the disc supported 2.4x burn speed. Our practical tests proved that this disc is recordable at 4x, too.

  

The scanning for errors performed by the two test programs revealed a low number of errors in total, and with low peaks, which is quite compliant with the industry standards. We can regard this disc as a quality medium which won't disappoint you at work.



Imation DVD-R 8x

  

This DVD-R blank turned out to be a product of Fuji Film.

  

The diagrams are self-explanatory: we see that the peaks of PI errors and failures are many times above the norm. Note that the quality is quite acceptable in the middle of the disc, but degenerates dramatically at the beginning and end. Considering that, this disc won't suit you if you need guaranteed burn quality.


Intenso DVD+R 4x

  

The disc selling under the Intenso brand is manufactured by Moser Baer India Ltd. You may have noted the non-standard packaging of this product: there's a special lever for ejecting the disc through a side of the plastic slim box. With this design, the disc won't slip out and get damaged even if you let the box drop down. The only drawback of this solution is that dust may come into the box through the constantly open slit.

  

The two screenshots testify to the high quality of the disc. The results in PI errors are excellent; the maximum of PI failures is low enough, too. There's only one spike of PI failures which coincides with the acceptable limit.

So, we've got another quality disc here, which is unlikely to lose your recorded data.



JVC DVD+RW 2.4x

  

The box with a rewritable disc from JVC has no indication as to the burn speed it is rated for. The disc itself has no such indication, either. DVD Identifier says the manufacturer of this disc is Ricoh Co. Ltd., and the disc is rated for 2.4x. Our practical tests confirmed the latter point.

  

The scanning of the disc proved its high quality. The maximums of errors never exceed the acceptable limits. The total of the errors is rather low, too. From the point of view of quality, this disc certainly deserves your attention, if you're satisfied with its not very high maximum burn speed.


JVC DVD+R 4x

  

This write-once DVD+R disc from JVC is, like the previous model, a product of Ricoh Co. Ltd.

  

The quality is high here. The maximums of PI errors and failures fit within the norm, and their total number is exceptionally low. The overall appearance of the diagrams suggests that the quality of the recording layer is uniform along the entire surface of the disc. You can get nothing else but a feeling of deep satisfaction from using such media.



JVC DVD-R 4x

  

The last of the three tested discs from JVC is a product of Taiyo Yuden Co. Ltd.

  

The screenshots show that everything would be normal if it were not for the final stretch of the disc. This zone spoiled the overall picture. The maximums of the errors are fully within the norm almost on the entire disc, but the single spike at the very end strikes out the earlier achievements. It is possible that this is a defect of the particular sample of the disc we tested. So, the JVC DVD-R 4x is a good choice, but there's probability of getting a sample with an artifact like the one we registered.


Memorex DVD-RW 2x

  

This DVD-RW disc selling under the Memorex brand proved to be a product of TDK Corp.

  

Our tests show that the maximum number of errors in both cases is much smaller than allowed by the standards. Their total number is small, too. We can see stability of characteristics along the entire surface of the disc. So, our summary is simple - this disc will suit all users who are satisfied with 2x as the max burn speed.



Memorex DVD+R 4x

  

DVD Identifier reports this DVD+R blank is made by CMC Magnetics Corp.

  

The programs scanned the disc to yield highly positive opinions about its quality. The measured maximums of PI errors and failures are noticeably below the limit, and the total number of errors is rather low, too. Like with the previous disc from Memorex, we have to admit its highest quality and recommend it to all of you.


Memorex DVD-R 4x

  

We've got two DVD-R discs from Memorex marked as rated for 4x burn speed. They should be identical in theory, but a slight difference between the paper inserts in the plastic boxes made us suspect that the discs inside were different, too. This supposition came true afterwards. The first disc proved to be a product of CMC Magnetics Corp.

  

The results of this test are incomplete because Nero CD-DVD Speed would freeze at about the middle of the disc. Even without that we can notice some grave problems with the quality of the recording layer. There are spikes of PI failures higher than described by the standard by a factor of ten, although the maximum of PI errors is within the norm. Judging by the overall look of the diagrams, the main problems with quality are in the middle of the disc. So, we have to reject this medium as defective. You may want to buy it only if you have no other alternative.



Memorex DVD-R 4x

  

The second DVD-R blank rated for 4x speed proved to be a completely different product, manufactured by Moser Baer India Ltd. This disc differs visually from the previous one in having the red circle with the text "No.1" on the paper insert in its case. Another point of difference became apparent during the tests: Nero Burning ROM permitted to burn this disc at 8x speed, too. We refused this offer, though, sticking to the chosen test methods.

  

The scanning of the operational surface of the disc says everything's OK with its quality. The maximums of PI errors and failures are within the norm. The quality of the recording layer is quite stable along the entire disc. So, we vote in favor of this one - it definitely deserves your consideration.


Philips DVD+RW 4x

  

The blank selling under the Philips brand is actually made by Ritek Corp.

  

The results of this disc in the tests are very good, if not perfect. The maximums of the errors are much lower than the limits set by the standards. Then, the overall stability of the disc is visible from the diagrams. So, here's another good DVD+RW for you.



Philips DVD+R 8x

  

This DVD+R blank is a product of Optodisc Technology.

  

The results are highly disappointing, though. This blank obviously lacks quality. The maximums of PI errors and PI failures are many times higher than any respectable disc should be allowed to commit. The quality of the operational layer isn't constant, too. There can be only one opinion - you must be an enemy to yourself if you buy such discs.


Philips DVD+R 4x

  

Another DVD+R blank from Philips, rated for a lower speed, proved to be made by CMC Magnetics Corp.

  

The results of the tests are most pleasing. The maximums of PI errors and failures are within the norm, and their totals are low, too. The errors are evenly distributed along the disc. Such media are going to make a good purchase.



Princo DVD-R 4x

  

Quite an unusual situation in this test session, the DVD-R 4x blank from Princo is actually made by Princo Corp.

  

The disc fully meets the requirements to the maximum of PI failures, but the maximum of PI errors is high above the norm. Thus, we can't call this disc a high-quality product. You may have problems with it.


RiDATA DVD+R 16x

  

The Taiwanese Ritek Company founded in 1988, was the first one to produce a CD blank disc in its home country in 1990. In 1992, its production got ISO9002 certified, and in 1997 - ISO9001. In 1996 Ritek produced the first DVD disc in Taiwan.

I decided to mention all these facts here on purpose: to show that Ritek is no newcomer in the optical storage media market, but more like a trendsetter.

  

The disc sold under RIDATA brand name is manufactured by Ritek Company . Unfortunately, the blank from the round plastic box didn't meet the allowed requirements for the number of errors. As you can see from the graphs the second part of the disc space turned out to be a major problem. It looks like this disc will not be the best choice if you intend to record it at the maximum write speed.


RiDATA DVD+R DL 2.4x

  

  

DVD+R disc designed for dual-layer recording was tested in 2.4x mode. The screenshots show pretty logical results. The entire first layer of the blank disc was recorder beautifully. The quantity of both types of errors, as well as their maximum indicates very high quality of this zone.

However, when we shift to the second layer, the picture changes dramatically. The maximum error rate starts exceeding the allowed maximums according to the ECMA standards, although this is not a global disaster. It happens just a few times and is most meaningful in the very end of the disc space.



Smartbuy DVD+R 4x

  

The disc Smart Buy Digital Media Ltd. is selling under the Smartbuy brand is actually manufactured by Prodisc Technology Inc.

  

As you can see from the diagrams, the total number of registered errors is very close to the absolute minimum. The maximums of errors of both types are far from the limits set by the standards. The overall appearance of the diagrams indicates stable quality of the recording layer along the entire surface of the medium. That's a good disc which is going to ensure safe recording of any information.


Smartbuy DVD-R 4x

  

The second Smartbuy blank is also manufactured by Prodisc Technology Inc.

  

The quality of the disc, although it is lower than that of the previous blank, is quite satisfactory. The maximums of PI errors and PI failures are within the norm. The single defect of this disc is the certain irregularity of the recording layer - you can see that the burn quality is worse at the end of the medium. Anyway, this disc is also going to be a good choice.



Sony DVD+RW 4x

  

That's another rare case in our practice: the seller and the manufacturer of this DVD-RW is one and the same company, Sony Recording Media Co.

  

It's hard to find any faults with the quality of the written disc. The maximum number of errors is much below the ceiling as set by the industry standards. The total number of errors is small, too, while the stability of the surface of the blank is beyond doubt. This disc from Sony can surely be recommended for use.


Sony DVD-RW 2x

  

The other rewritable disc under the Sony brand is actually manufactured by Ritek Corp.

  

The diagrams indicate that we've got another high-quality product here. The spikes of errors are much lower than described by the standards. The stability of the operational layer of the disc is beyond doubt, too. The total number of errors is rather small. Thus, this disc can satisfy any user who doesn't need the highest speed of burning.



Sony DVD+R 4x

  

This DVD+R blank comes from Mitsubishi Chemical Corp.

  

The performance of this disc is truly impressive: the peaks of PI failures are only as high as 1 failure! The maximum spike of PI errors is only 9 errors high. We can't find any other word to describe that except 'impressive'. Added the small totals of errors and the stable quality of the operational surface, no other comments are necessary. This medium can be recommended for purchase without any reservations.


TDK DVD+RW 4x

  

Philips proved to be the real manufacturer of this DVD+RW disc.

  

Our scanning the recorded disc with both test programs revealed no quality-related problems. The maximum number of errors of either type is within the norm. Judging by the look of the diagrams, the disc also has no problems with the stability of the recording layer. We recommend this disc for purchase.



TDK DVD+R 16x

  

This DVD+R disc rated for the maximum burn speed of today, 16x, is both manufactured and marketed by TDK Corp.

  

The diagrams with the test results say the quality is normal. The total number of errors is small, while their peaks are much lower than specified by the industry standards. The overall look of the diagrams indicates that the recording layer of the disc is stable enough. Considering this performance, the disc can be recommended to all users who need the fastest write-once media.


TDK DVD+R 8x

  

This DVD+R disc with a maximum burn speed of 4x is manufactured by Ricoh Co. Ltd.

  

There's difference between the two diagrams with the results of the test. Nero CD-DVD Speed says the maximum of PI failures is two, while KProbe says six. The difference seems big, but if you take a closer look at the diagrams you may note only the first value, i.e. two failures, in both of them. The peak of six PI failures was evidently registered as a single spike which is not displayed on the diagram according to the selected 'Remove the spike' option in the program's options. Such a spike doesn't affect the overall quality of the disc much.

The total number of errors is rather small, but there's an increase of them towards the end of the disc. Note also that the maximum peaks of PI errors are, too, much lower than the limit set by the standards. On the whole, this medium seems a good product, worthy of your consideration.



TDK DVD-R 8x

  

The last of the TDK discs included into this review is actually manufactured by TDK.

  

Alas, the disc failed the test. The maximums of errors exceed the limits imposed by the standards. Besides that, you can see certain non-uniformity in the distribution of the errors along the surface of the blank. So, here's our verdict: this disc lacks quality to be a suitable medium for you. At least, you shouldn't burn it with the Lite-On drive we used in our tests.


Verbatim DVD+RW 4x

  

According to DVD Identifier, the real manufacturer of this Verbatim DVD+RW disc is Mitsubishi Kagaku Media. That's another way of saying Verbatim, because Verbatim is a daughter company of Mitsubishi's.

  

You can see that the peaks of PI failures slightly exceed the acceptable range - five or six (the two test programs differ in their opinions) instead of the allowable four. But it's all right with errors of the other type - their maximums are far below the required level. We suppose the users won't have any troubles with this disc.



Verbatim DVD+R 8x

  

This DVD+R blank is manufactured by Mitsubishi Chemical Corp.

  

The scanning of the operational layer of the medium betrays its low quality. The maximums of PI errors and failures by far exceed the norm. The quality of the recording layer is not stable, judging by the appearance of the diagrams. It is worse at the beginning and the outermost half of the disc. We don't think this disc is going to be a good purchase for people who care about the safety of the recorded information.


Verbatim DVD+R 2.4x

  

This disc is made by Mitsubishi Kagaku Media. This is the only dual-layer blank in this review.

  

So what about quality? The sudden increase in errors on the second layer is evident of course. This fact is quite comprehensible from the technological point of view as it's more difficult to ensure quality on the second, farther layer. The peak of PI errors on the second layer by far exceeds the recommended limit. The maximum of PI failures can be considered normal, though. Although Nero CD-DVD Speed says there are seven PI failures, KProbe found only four, probably ignoring single spikes due to the selected data display mode. So, we've got a medium whose quality is immaculate on the first layer, but is much worse on the second layer. There are few dual-layer media available as yet, so you may want to consider this one as an option.



Verbatim DVD-RW 2x

  

That's another 'native' Verbatim, manufactured by Mitsubishi Chemical Corp.

  

You can see from the diagrams that the quality of the disc is high. The maximums of PI errors and failures are far below the limit as set by the standards. The overall appearance of the diagrams testifies to the stability of the operational layer of the disc. This is a very good medium, if you're satisfied with the relatively low burn speed it supports.


Verbatim DVD-R 8x

  

The last Verbatim we tested during this session is also a product of Mitsubishi Chemical Corp.

  

This DVD-R can hardly be characterized as a quality product, though. The spikes of PI errors and failures are two times above the highest acceptable value. As you can see, the problem lies in the beginning of the disc - the quality of this zone is much worse than the rest of the medium. Considering this, we don't recommend this disc to you. But it is quite possible that the problem zone is a defect of the particular sample of the disc we tested.


XIDEX DVD+R 8x

  

The disc selling under the XIDEX brand proved to be a product of CMC Magnetics Corp.

Nero CD-DVD Speed couldn't read the written disc; KProbe did the reading, although with some visible effort. The diagram above shows you the reason: the maximums of PI errors and failures are far above any norm, especially the failures. Money you are asked to pay for this medium should be spent for some better purposes instead. Thumbs down to this one.



Conclusion

We have already said a few words on each of the participating discs, but now we will try to make some generalizations. There's a pragmatic problem before each user: are you guaranteed to have high burn quality if you purchase media from brand names only. We can reword it this way: is it possible to find good media at low price? We guess this test session has helped to answer this question: expensive media are not necessarily the best ones as concerns quality. A renowned brand does not give you any warranty here - you can have the same problems with an expensive brand-name disc as you do with cheap discs from obscure companies. Considering that discs selling under different brand are often a product from the same manufacturer, it is the more reasonable to choose the one that costs less. You don't want to shell out more just for the brand, do you?

For an easier reading of the results of the tests, we created summary tables that include all the reviewed discs divided into categories by their format. For better readability, if the maximums of errors of both types fit within the acceptable range as described by the industry standards, the disc is highlighted with blue (click the tables to enlarge and see more details). To make the tables even more informative, we highlight the discs that are approved by both programs as having appropriate PI error and failure parameters with green. If this successful result is achieved in one program only - the disc is highlighted with yellow. Blanks of these two colors should provoke no problems in use. Discs that couldn't pass the quality test in neither of the programs are highlighted with orange. With this rather formalistic approach some discs suffer because of their having single spikes of errors but are otherwise quite compliant with the requirements. Such discs should also be considered as quality ones, but you have to refer to their particular diagrams to agree or disagree with that. We personally think that orange is a kind of warning that there may be possible problems with such media. And lastly, the discs without any of the colors are media that our test drive couldn't burn at all. There are three such discs, two of which are actually twins, selling under different brands. As we said earlier, this incompatibility may be eliminated in the next firmware update for the Lite-On drive.

As for the two programs, the two test tools that we used in our tests, Nero CD-DVD Speed and KProbe yield very similar results in most cases, but sometimes they do disagree. CD-DVD Speed is a more universal tool, but sometimes it freezes during the scanning of problem discs or refuses to work with them at all. KProbe is originally intended for optical drives manufactured by Lite-On (drives on Mediatek chipsets), which limits its scope somewhat. Sometimes it has problems with DVD±RW discs when it wrongly determines the boundaries of the recorded area in the automatic mode and starts to throw messages about servo-errors at you. This can in some cases be cured by a preliminary reformatting (erasing) of the disc. Otherwise, you have to identify the test range with an LBA address which you must provide. This is not quite convenient if you want to check out just a single rewritable DVD disc and do not know the exact spot where the recording ends. Thus, it's hard to tell which of the two programs is better. Each has its own pros and cons.

In this review we didn't cover such issues as the time the written information is retained on the disc and the ability of the rewritable discs to keep their quality up after numerous write/erase cycles. We hope you understand why - such tests would just take too much time. Another disturbing question for any user is how the burn quality depends on the burn speed. Many people hold the opinion that the data transfer to the medium can only improve at reduced burn speeds, so the quality is the best at the minimal speeds. We think this is an intriguing topic for discussion and we are going to deal with it in one of our upcoming reviews.

The last thing we want to remind you is that the results we got in our tests are true for the particular conditions described in the Testbed and Methods section and may be different if the discs are written in other optical drives or in different burn modes.