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11th March 2011, 15:32 | #121 | Link | ||
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It's a pity you can't post screen shots which back up your experience such as a better quality burn than what I'm getting with Verbatim today. 20 years experience, yet while making lots of generalisations you haven't actually given any examples of your own experiences with media longevity, or lack of it. Quote:
No, they don't.... do they? |
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11th March 2011, 15:56 | #122 | Link |
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You see, probably you'll understand once that companies do the products batchwise, then move to the next product. The same is true for retailers and wholesellers. They don't buy 1 Verbatim, 2 TDKs, 3 Maxells, they buy one container of Verbatim. The PC shop nearby buys them in smaller quantities, you even less. There's a great chance that your disks bought today are from the same batch as those bought 2 years ago, because of this triple buffering. And if the containers were not empty, you'll buy the same disks also in the next 2 years. I assume all disks in one production batch are equal (they are not). But a batch of product A is different from the same product, if meanwhile the production line changed.
The visible drop in quality for Verbatim occurred when they changed from DataLifePlus to DataLife. There are no longer DataLifePlus, at least not official (but a lot of fakes). The last good product from Verbatim was the Archival Type (which was not so well received, partly because it was graded only 8x, oh, gosh, I wanted burn it at 24x for the price I paid).
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11th March 2011, 16:43 | #123 | Link | |
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I'll eagerly await some screen shots of this visible quality drop. As I said, the burns you were getting from those blanks must have been phenomenal to be better than the burns I'm getting today. Last edited by yetanotherid; 11th March 2011 at 17:39. |
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12th March 2011, 15:27 | #126 | Link |
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Not sure. Someone made a thread worried about having a dvd with hundreds of thousands of PI errors(PIF was 0.02 average), and one of the cdfreaks mods said it was normal. And another one said the burn was "good but not archive quality". He didn't specify what that was. He just said it was fine for normal stuff.
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15th March 2011, 18:04 | #127 | Link |
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Archive quality is not measured in PI/PO values. It is measured in how well that particular disk withstand the time. I said it before, and I repeat it now, lower PI/PO are a prerequisite for long term storage, yet these are not enough. Supposingly one keeps the burned disks in the darkest darkness, in a vault that is humidity controlled, and keeps it from scratching, PI/PO are extremely relevant, lower values offer a higher buffer against ageing. In normal usage however, scratches, humidity and UV radiations are much more important.
However, no matter how low is the average, spikes (bulks of high PI/PO) are not allowed for archival purposes.
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16th March 2011, 18:50 | #128 | Link |
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Dye stability and error rates are 2 different stories...the ideal is to have a stable dye(TTH01 for instance) and burn it w/ a well adapted firmware. But a worst case scenario would be a poorly burned highly stable dye against an unstable dye w/ very low Pi/Po right after the burn. The former will not rot overtime, the latter very much will.
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22nd March 2011, 14:02 | #129 | Link |
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I can't see the tab Disc Quality in DiscSpeed, instead there is ScanDisc. I checked an 8 years old DVD in scandisc and "surface scan" was 100%, everything green, surprised. Is there a way to check my discs quality, (even with my shitty drive)?
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22nd March 2011, 21:45 | #131 | Link |
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Yes, I know, when they are ok, they are ok. I just thought about checking the oldest ones to backup, with my laptop HL-DT-ST CT10N drive. If there's any software I can use for disc quality.
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23rd March 2011, 15:26 | #132 | Link |
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You missed the point.
Nobody can measure the quality of a DVDR, unless s/he uses special tools (there have to be a special drive and a special software), even then there's no 95% or the like, just OK or FAIL for each parameter (there are around 20 IIRC). Not only that that Philips optics is nowhere to be found (I mean in the consumer realm) and even then it will lack the special firmware that allows the reading of all parameters (it includes here the raw RF laser output), but also nobody will ever spend ~20+ hours (each parameter is measured once and at 1x only) for each disk. The LGs are quite good readers, far from being shitty. For a shitty result try a NEC (Optidrive), except for the 4550 model which stands out in this respect.
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24th March 2011, 22:44 | #133 | Link | |
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You can download the latest version here but I'm not sure if it's a full free version. http://www.nero.com/enu/tools-utilities.html It seems odd someone would claim you can't test the quality of a disc given the availability of software for just that purpose, and given the same person has posted screen shots of tests they've run on their own discs. Nero doesn't actually give the quality as a percentage as has been mentioned earlier but it does give a disc a "quality score". Anything over 90 should be easily readable. Maybe quality tests aren't 100% accurate, and of course not all drives are capable of reporting errors correctly, but they're certainly a pretty good guide as to the quality of the disc. There's another program for running disc quality checks here, but I don't think it's free. http://www.cdspeed2000.com/ |
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3rd April 2011, 17:54 | #134 | Link | |
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One can have a sort of quality index for a DVDR for a particular reader. The same disc may be 96% (Nero) when read by an LG, and 56% when read by a NEC. Values invented.
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3rd April 2011, 22:40 | #135 | Link |
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It was understood. Maybe you missed my point when I said that even though testing for errors mightn't be 100% accurate it's still a pretty good guide as to the quality of the disc? Which obviously it must be, given you posted burn test results yourself and requested others do the same earlier in the thread. Why would you do that, only to argue later it's not possible to test the quality of a disc?
Some drives are better readers than others and different drives will no doubt report different errors. Claiming one drive will report a quality score of 96 while another will report a quality score of 56 seems to be inventing exaggerated values to me. I'd imagine a good quality burn will still test as a good quality burn in both drives while a poor quality burn will test as a poor quality burn in both drives even if the reported errors aren't exactly the same, so it'd still be possible to assess the burn quality even if it's not an exact science. Chances are the good quality burn will test as good quality in both drives (because it's good quality and easy to read) while the poor quality burn might look worse when tested in one drive than it does in the other (because one drive is better at reading poor quality burns). Do you have any examples you can post of a disc which appears to be of a good quality in one drive while bad in another, or where the reported quality is different enough to show there's no point to testing discs for quality? Last edited by hello_hello; 3rd April 2011 at 22:57. |
4th April 2011, 08:12 | #136 | Link | |
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Not at all. See NEC ND-3540 vs. Plextor PX-750. The percentages represent the good sectors (green) vs. the unreadable ones (red). In the green zone are also included the corrected sectors (ie sectors that were faulty but the drive used the CRC algorithm to recover the valid data). As long as one uses the same drive to check the discs, no problems, s/he has at least a reference. But combining data from various drives, with various discs, and various programs (I use Plextools and pxscan, some use KProbe, other use CDSpeed and so on) is not a good practice IMHO.
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4th April 2011, 09:44 | #137 | Link | ||
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It seems to me you've only offered a graph which shows some drives can read a poor quality disc better than others, and there's nothing to say it was even a burned disc or what sort of quality would have been reported by each drive. No doubt the drives which could read more of the disc would have reported a better quality than those which could read less, but do you really think your graph proves any of the drives would have reported the disc quality as being anything but low? I think you'll find I've already acknowledge some drives can read poor quality discs better than others and quality scores will vary as a result, but I still maintain it doesn't negate being able to test discs for quality even though it's not an exact science and your graph does nothing to prove otherwise. Do you have anything which actually relates to testing a disc for quality and which shows the results vary so much between drives a disc quality test is meaningless? i.e. reporting PI errors and failures etc. Quote:
However there seems to be no logical argument offered as to why combining data from various drives, discs and programs is not good practice. If disc testing isn't an accurate science, surely having more than one reference makes it somewhat more accurate than only having a single reference, the accuracy of which is unknown? Last edited by hello_hello; 4th April 2011 at 09:56. |
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4th April 2011, 09:49 | #138 | Link | |
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If you can't test for quality, what are you trying to achieve when you test the quality of your discs? |
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4th April 2011, 09:54 | #139 | Link |
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There are pressed (ie original) DVDs that do not pass the standard testing procedure, they have at least one FAIL for some parameters.
That is testing. The rest is approximations. They are good as long as one uses only one drive, and only one software, and only one measure. Some people say 95% in nero. Perfect, be happy. But as long as the drives are required only to play DVDs that comply with the specs (ie only OKs, not a single FAIL), a particular disc may have playback problems on other systems. The drive manufacturers gave us a gift actually, as most drives can read also out-of-specs discs (I had once a DL with some 1300 PI for about the whole second layer, yet perfectly readable with no speed-down), but this is no guarantee.
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4th April 2011, 10:00 | #140 | Link |
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Some drives can read poor quality discs better than others. Most drives can read discs which are way out of spec. Nobody's arguing about it. Time to move on.
When you've got something which relates to the subject of testing a disc for quality I'll be keen to read it. |
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