Precision, accuracy, and reliability of disc quality (PI/PO/jitter) tests

About variations, most people don’t get the numbers in perspective. I’ll refer only to PIE values in the following considerations.

I’ve seen people complaining that for example PIE max levels ‘doubled’ between two scans, when actually it was the peak values being respectively (Benq scan) 8 and 16.

Now let’s do some maths, in the form of a percentage of the theoritical 280 maximum admissible value. A variation of 8 then represents a 2,85% variation, in PEAK values… which as everyone should know are most of the time not relevant, unless these peaks are numerous, evenly spread and constant.

I never tried, as yet, to quantize what I consider a “significant” variation in PIEs between two scans (of the same disc in the same drive). I’m very much of the intuitive type, being after all a musician, not a techician. But I think it would be about a minimum variation of 5% in average levels, which would be, for example, a difference between an average of 50 and an average of 65. When numbers decrease, under 25 PIEs, I consider it kinda anal to worry about any differences in averages. When numbers increase, variations are more of a concern. At least that’s the way I see it…

So about degradation, what I look for is not the difference between just two scans, what I’m looking for is a trend. Are several discs from this MID/batch showing higher levels after some time? Do discs from another MID/batch do the same, or are their reported numbers more constant? Comparisons, comparisons, comparisons. NOT absolute numbers.

That’s one of the main problems, IMO, with the way many users on this board consider scanning. Too many get so totally obsessive, even irrational with the numbers, that they can’t see the big picture anymore…

I ask what is accomplished by sitting around and testing so many different discs? What is the ‘End’ to those ‘Means’? What I’m saying is since it is not exactly too accurate, and far below precise, what do you do as a result of your tests? Throw away the poorly scanned discs?
That’s why I’m questioning the testing ‘numbers’. My DVD copies have always been fantastic, and I won’t allow myself to obsess about the testing because I already know what steps to take to ensure great and durable Back-ups. It was never a concern until some people tried to convince me that something was wrong with my DVDs and I should test them to make sure their O.K.
I already knew!

edit

Rock -would you mind me asking what DVD media you use ? what Burner ? and what Software ? Although I am also happy with my disks I’m always interested in seeing if there is a better way

Harry, beautiful comparison, I think you sold me on the liteon 1693, you need to
use ImgBurn with dvdinfopro, LUK’s still making the burn engine better.

To me one of the best things about DVD Decrypter is the way that it writes ISOs. I used to use Nero to write from files and then one day I tried Decrypter to burn an ISO – the difference was fantastic. So I wrote to LUK to say thanks and to ask why it should give a better burn. As I recall he replied that using it to write an ISO should give neither a better nor poorer burn. Anyway being superstitious I have continued to use DVD Decrypter to burn. I have tried ImgBurn but it “just doesn’t feel right” . habit I guess ? but then I always defrag before a burn, I put the disk in the tray for 10 minutes to walm it up, you know all the usual superstitious nonsense… and as long as disks continue to play and data is not corrupted I will continue in the same old way.

It’s probably true with Benq and LiteOn drives, but I don’t think it is with some Pioneer drives (108, 109) and the last Nec family (3550/4550/4551).

Discs that show:

  • a perfect TRT in these drives and in other drives
  • very good to most excellent scans in Benq, LiteOn and the Nec 3540 (previous model),
    Show out-of-specs and very funny-looking (not to say plain silly) PIE levels when scanned in these drives.

I experienced this (and saw reports from others) with many MIDS, including MCC, TY and Ricoh discs, so media quality is ruled out I think.

Luckily, the PIF reporting of these new NEC drives is very consistent and is definitly “usable”. :slight_smile:

Yet there is much confusion now in the NEC forums with guys having just bought a 3550 or 4550 drive, using it for scanning, seeing PIE levels far over 280 and not understanding what’s happening to them. :eek: :frowning: - I have a hard time explaining them that they shouldn’t worry as long as PIF figures are good and the reading curves are perfect. :doh:

I had to through in my two cents when I saw this post. Excellent discussion.
And I think Francksoy nailed it,
Although I have had alot of fun messing with testing, trying different firmwares etc. I believe when you get so low in the errors it is useless to say the errors have doubled or are xx% higher, There are too many variables throughout the process to say "my errors have doubled between burns or even tests when the pifs are down to 25~100. I do think that it is a good way to look for trends in degradation, even though since I started using my NEC 3500 I have not seen any degradation with the TY 8x I use. I mainly look at the last of my older disks, A few CMCs, and RICOHs.

I get your point. :iagree:

Actually I use scanning a lot because I like to play with many different MIDs in different burners. Honestly, if I wasn’t so addicted to this DVDR game in general (LOL), and only used MCC004 (Verbatim-branded), TYG02, YUDENT02, RICOHJPRN01 (Ricoh-branded) or TTH02 (TDK-branded), I think I wouldn’t scan more than a disc or two every six weeks, and would merely perform transfer rate tests to check my burns. Actually I think I’ll come to this sometime soon, as my wife is getting kinda concerned with this DVR madness. And I can’t blame her. :bigsmile: (Also I’ve just, at last, finished to transfer my video collection, 676 burns and about as many scans and TRTs in 9 months, I need a BREAK! ¨*SIGH**)

My point being similar to rdgrimes’, for many users, assuming they found a good MID/burner combination (either from good advice or personal testing) and buy only premium discs, scanning is not absolutely necessary. A TRT performed with the “accuracy” setting can most probably catch any possible new batch (or aging burner) problem. Anyway IMO it’s better than scanning with poor understanding of the “big picture” and seeing only the numbers.

I’m still convinced that properly conducted and interpreted scanning can help in avoiding many problems, better understanding of how burners behave (like the poor -R re-linking of recent NEC drives for example), and in wisely choosing the right MID/burner/firmware combination. :iagree:

[off-topic]
Oh and thanks for the compliment :cool: - BTW I’m interested in how your CMC discs are doing, degradation-wise. I’d like you to keep me informed, if possible? (take it to PM :wink: )
[/off-topic]

I haven’t called anyone anal. :disagree: - I stated precisely this: “When numbers decrease, under 25 PIEs, I consider it kinda anal to worry about any differences in averages”. It’s a general consideration and aims at no one it particular, unlike these comments of yours it seems. If you feel like getting personal with me, you don’t need to post rude comments in the threads, better take it to PM as other users have no interest in this.

If you feel I’ve been rude or disrespectful to someone, you may always report my post to a moderator.
http://club.cdfreaks.com/announcement.php?f=96&announcementid=37
*

So whats being said is that if someone buys only premium DVDs like say Verbatims (which I use exclusively) and MIJs it isn’t really necessary for them to use the disc quality testing?
I thought that was what I said? I’m sure that CD Speed has some decent testing uses but the more I learn about some of the tests and what it can be used for , I see less and less need for them as well as some of its reliability.

Now I haven’t tried all the testing software but I ask why is it considered so important?

Use premium media, burn at a rate that your drive and/or system can handle, and take good care of them, why would testing be necessary?
If you use some crap media and you find out later that it is crap, maybe O.K.
But I haven’t seen anyone come up with figures or test results showing the long term degradation. I think I’ll take the NISTs’ word on testing results anyway. When you start with crap you’ll know in the very beginning, right?

edit

That is exactly what you did in your first post in this thread. You started attacks even before I had talked about my observations.<O:p</O:p

Perhaps if you would devote your time to reading ALL of a thread instead of just quoting what you think will support your own “cause”, you contribute more to this discussion.
Science is based on solid evidence, not on opinions. Observations made by others are also important, otherwise we need not listen to others.
<O:p</O:p

I’ve been aware of that for some years.
But obviously you did not know the reason.
<O:p</O:p

The point I’m trying to put froward is that it doesn’t matter what is considered “Accurate” by anyone. The purpose of scanning is not to acheive “Accuracy” in error reporting.
Where have I said that purpose of scanning is to acheive “Accuracy” in error reporting? “Accuracy” is something very difficult to achieve, if not impossible. But it is much easier to pick out the obviously inaccurate ones. <O:p</O:p

There must be a full moon in the Blank Media forum at the moment. What’s wrong with you guys. You’re spending more time bickering than in open discussion. If it doesn’t stop now, some of you are going to find yourself with a timeout.

Rocky Point, enough. Time to drop it. You have been warned. :cop:

I’ll leave this thread open for now. If there are any more outbursts, it will be closed.

Posts edited and deleted…

@ Rocky Point

You may read the following thread first:

http://club.cdfreaks.com/showthread.php?t=161005

Let me know if that answers part of your questions. <O:p</O:p

I shall talk about reproducibility later, but my time is tight, so be patient.<O:p</O:p

I think I’m done. I thank all those of you who have been welcoming and willing to help, but I don’t think I’m going to posts in these forums again.

Somethings not right with some of the things going on here. Maybe there should be a re-examing of what or who is allowed to say what.

Rock -would you mind me asking what DVD media you use ? what Burner ? and what Software ? Although I am also happy with my disks I’m always interested in seeing if there is a better way
Last edited by C0deKing : 1 Hour Ago at 10:36.

Just curious - what was edited and why ?

@ Frankensoy

I think I wouldn’t scan more than a disc or two every six weeks, and would merely perform transfer rate tests to check my burns. Actually I think I’ll come to this sometime soon, as my wife is getting kinda concerned with this DVR madness. And I can’t blame her.

My wife has been concerned also. For a while she thought I was spending all my time trolling around for Pron! :bigsmile: :bigsmile:
I’ll PM with some info on the other disks later, Have to dig them up from the dry, dark recesses of my closet. :slight_smile:

Now, I didn’t see what was edited from Rocky’s post(s) but his basic questions and/or conclusions still seem to me to in need clearing up… (from my perspective)

In my humble opinion, DQ testing using CDSpeed (or simmilar software) is of value, even for people using known good burners and media. Why? because nothing is good 100% of the time.

Case in point… I have a BenQ 1640, which by most accounts is a excelent burner, a respectable reader, and seems to report errors to reasonably well to software like CDSpeed. I never owned any Taiyo Yuden disks untill recently (about a month ago), and purchased them, largely because of all the rave reviews of Taiyo Yuden disks. I have also recently purchased disks made by MCC (Verbatim 16x branded)… Well my batch of Taiyo Yuden (Fuji MIJ 8X branded) are basicly flawed near the final 600MB of the disk. They sometimes play OK in DVD players, and proform Excelent when you put less then 4000MB of data on them. It would have been really hard, if not nearly impossible to have detected the problem with my batch of Taiyo Yuden disks, without scanning of some sort…

Now, here is where I beleive Rocky Point, is missing the point...   Just because a movie DVD (or even a data DVD) plays fine... does not mean that it's 'flawless'.  It merely means that it can play in some DVD players, and the error correction is able to correct the amount of errors that the player encounters as it's reading the disk. The players could be encountering 99% of the total number of errors that it's able to overcome, and if it encountered a small number more errors, it could become unreadable (at least in certian portions of the disk)...   Just because a disk plays, doesn't mean it is flawless, in fact it could be full of flaws, just that the flaws haven't exceeded some level that would render the disk unreadable...  

And… Can a disk degrade over time? YES, sure it can… for a variety of reasons… Exposure to exsessive heat, humidity, or lite can all cause degredation of the disk’s ablity to be read, or to be written. Not to mention scratches… Do I have proof of this personaly? No… but if you’ve not seen any evidence of this, then you haven’t looked very hard…

I will not vouch for the total accuracy of the following reports, but if you think even high quality disks can not deteriorate, you’d better read through the following…

http://club.cdfreaks.com/showthread.php?t=144159&highlight=Longevity

One final note... I'm not stating any of this to try and chastize, or to critize anyone for voicing their own personal opinions, but I do think Rocky Point is missing some critical points about DVD quality and/or if there is any value to doing personal testing (using what ever means they can afford)... I feel strongly that anyone using DVD to store any data of any value, should understand as much as they can about what exactly it is they are doing. 

Meanwhile… I’m not trying to say, that you or I should scan every single disk they own, or record… but periodic testing of some disks, can give you usefull data… If you understand what it’s telling you.

agreed. I have a number of older DVDs which still play fine in any one of a number of players BUT fail when I try to copy to my hard drive. Scanning at the burn stage and again a few months later might have helped me save the content

Also regarding Taiyo Yuden - I used Fuji for a while and thought they were great. Then Fuji switched to Ritek in the UK and I started to use Unbranded Taiyo yuden. Now I wouldn’t go back even if Fuji started to use Taiyo Yuden.

a little cleaning and polishing and my LG and dvdfab saved my worst disk

I have done the same with damaged disks, but if the disk has degraded no amount of cleaning is going to help! :slight_smile: :slight_smile: