Looking for media quality assessment primer for newbie

vbimport

#1

Hi

I’ve just bought a DVD recorder and, in trying to figure out what media to buy, have discovered there is a huge amount if jargon for describing what to look for when running quality checks. Is there a good resource that describes what PIE, TRT etc etc are, what to look for in good scans and bad scans, what effects these factors have etc please? Basically a primer for a newbie.

I’ve looked up some of the acronyms (eg TRT, CLV, CAV) but would like to be able to find them all in one place, rather than repeat searching this forum. And I haven’t yet found anything other than opinions (valuable of course) on what is good and bad and what effects errors have. Really looking for the most objective primer I can find.

Its all rather confusing right now :confused: .

All the best!


#2

Short answer is that the reason all this stuff isn’t compiled better is that there is no clear consensus on most of it. The issue of quality scanning is enormously complicated and you probably shouldn’t even try to gain a super-deep understanding of it unless you were a comp sci/physics/EE major, or you are willing to devote a ton of time to it and just geek out.

If you eliminate the people who believe that testing with consumer level drives does not yield statistically valid results, then the only consensus out there is that each test- TRT, PI/PIF, jitter, etc. will at least give you a partial picture of how that particular drive read that particular disc at that particular time. Drawing any more far reaching conclusions than that becomes dicey, although most people (myself included) do so anyway for the sake of time and simplicity.

My advice is to approach the subject from a functional perspective. You may find with experience that a certain test is a fairly reliable indicator of success on your playback setup- or that in your experience, it reliably predicts how well the disc will age- take your pick of criterion. Just play around with CD/DVD Speed using the basic knowledge you have gleaned from your initial research and begin to establish your own feel for how the results correlate with playback/readability. Google and the forum search function are always there to help you confirm or overturn your own intuitive conclusions.


#3

Many thanks for all the info and advice btspm. Do a majority of people tend to look to a specific test (eg jitter) for quality check please?

As luck would have it, I do have a physics degree :bigsmile: . So, although I’m a bit rusty I but wouldn’t mind a tech-heavier primer. As well as a basic primer :slight_smile: . I’m sure the latter would be useful for many people.

Anyway …

My plan was and remains, unless anyone suggests alternatives, to burn each media I try (I have Verbatim 16x DVD+R MIT and Verbatim CD-R MIJ so far. Would also like to trial either the Fuji or Plextor TY02, and the Plextor TY CD-R) at as many speeds as possible, and for the uses I intend to put them, all with standard Plextor advanced settings. So, DVD+R will be documents (.doc, .xls etc), photos, and videos, and CD-R will be doucments (.doc, .xls etc), and audio. For compatibility I will likely be testing only on my own drives (so a couple of PC CD/DVD combis, a couple of PC CD drives, and a hi-fi CD drive).

I’m expecting to use CD-R purely for archiving rare audio CDs (ie CDs that were only printed in runs of 1000-2000, will never be re-issued, and are beginning to degrade). Actually, I suppose its more a case of replacing some of them, given the way that some seem to have failed completely already.

I’m expecting to use DVD+R for the rest, but would consider putting documents on CD-R if the error rates are better and/or the longevity is better. Will need to check the forums here for opinions and advice on the comparative longevity of DVD+R vs CD-R, specifically with MCC and TY. I vaguely remember reading some comments last year that CD-R is likely to have better longevity.

When I run the initial tests I’m going to keep conditions as consistent as possible by letting my drive cool down for probably 10 minutes between burns. Humidity should be fairly consistent throughout. It would be too difficult to try and standardise electrical conditions etc as well.

Once I’ve identified 2 or 3 superior results, I will then re-test with the drive switched on continuously.

And when I’ve done that I will re-test with fine tuning of the Plextor advanced settings (eg Gigarec). I believe that GigaRec will be of main interest with audio. Yamaha have sold a CDR/HDD combo box for some years that many claim creates better sounding CDs than the originals. The key seems to be a technique similar to (or perhaps identical with) GigaRec.

So, on this basis I should be busy until 2053 or so :slight_smile: , and will have a small pile of potential coasters (because I will be running the trials with a consistent source) but will then have a good idea of how to record for the future. Of course, this won’t address any stability issues with the discs themselves, but I will have the coaster pile available for reference and be able to re-run tests on the discs again at, say, 12 months.

Actually, writing this down has frightened me a bit. It seems like a VERY long process. Maybe I’ll be selective with the speeds I test at :-).

Re the testing tool itself, that will be Plextor Plextools Professional 2.36. Seems like there will be no newer version than this. Do you know how this compares with professional grade error checkers please?


#4

Plex tools always had a good rep- I’ve never used it personally, so I don’t know if or by how far other tools with more recent revisions have passed it by.

Just a thought, but have you considered archiving those CDs on a RAID 1 HD array? I don’t know how many CDs you are talking about, but checking for individual failures among any significant number of discs might be a sisyphean challenge.

As far as the most commonly used tests- the most basic is a transfer rate test- which is useful as a general overview, but not for much else. It is highly dependent upon what reading speed your drive allows for burnt media. Too low, and the transfer curve will always be smooth because the drive is not really tested. Too high, and speed reductions are not necessarily indicative of a fault, but rather of the drive butting up against its inherent limitations.

IMO, the most useful test is a PIE/PIF test for DVDs, or an equivalent C1/C2 test for CDs. In the latest versions of CD/DVD Speed, you can simultaneously run a jitter test, but again, I’m not aware if Plex Tools allows that configuration. In my experience, this test will almost never give a false positive- i.e., a large PIF or C2 spike will almost always manifest itself as a reading or playback problem. And it will only rarely give a false negative. In fact, I only had my first false negative the other day (which was quickly corrected when I reran the test after playback problems)- and that was with a drive on its death bed.

Letting the drive cool down is certainly a more robust testing methodology in theory, but might be a bit difficult to regulate since internal case temps fluctuate due to CPU load and HD activity anyway. And given that the tests themselves can take up to 15 miunutes per disc, you’re carving a big chunk out of your day. As long as the entire system doesn’t run hot, I wouldn’t worry about it.

No need to run tests at multiple speeds- you have to test at relatively slow 4x to get any useful results (some people choose to test at 8x instead). The test speed is inversely proportional to the total number of samples the drive can take during the test- thus, slower speed = more data. However, running the test at excessively slow speeds (like 1x) can mask some read errors that would crop up in everyday usage. 4x has been the standard as far back as I can remember, but some people have been using 8x more recently. As burning speeds increased, I suppose it felt a little silly using more time for the test than for the burn itself.


#5

I’ve just bought a DVD recorder and, in trying to figure out what media to buy, have discovered there is a huge amount if jargon for describing what to look for when running quality checks. Is there a good resource that describes what PIE, TRT etc etc are, what to look for in good scans and bad scans, what effects these factors have etc please?

I assume your are talking about a computer DVD burner and not a stand alone. Testing can be a pain, that’s why I always recommend that folks buy burners that have been reviewed by CDFreaks. They test a variety of discs and post the test results. The easy way to match media to your burner. The folks here have already done all the work.

That said it hard to go wrong with Verbatim -R’s (MCC code), they seem to work well with most burners and players.

http://www.cdfreaks.com/reviews/


#6

[B]btspm:[/B]

Any possibility of some more details to the drives you are using for these tests? As for testing speed, it is a contentious subject for consumer drives, as a reading of some of the threads in the blank media forum will show :wink:

[B]2020:[/B]

If you want some more information on testing & longevity of optical media, the NIST publications have some useful information.

http://www.itl.nist.gov/div895/gipwog/StabilityStudy.pdf
http://www.jhuapl.edu/GIPWoG/PDF/Public%20SP%20500-263%20November%202005.pdf

Also Media Sciences has some nice information on these subjects:

http://www.mscience.com/


#7

Don’t make hard on yourself just use good brand name media disc like "Verbatim, Sony, Fuji, or Maxell all last three “Made In Japen”.


#8

Many thanks for all the tips and advice :slight_smile: . I appreciate them/it.

My set-up is a Plextor PX-755UF, which I bought because of recommendations in cdrfreaks, cdrinfo, and others. I’ve bought MIJ Verbatim CD-R (ie TY) and MIT CMC Verbatim DVD+R (ie MCC 004), and would like to try TY02, all based on results I’ve seen for the PX-755 series and on comments/reviews/opinions in forums. So I’ve done all the burner and media research to simplify things for myself.

Re the testing itself, I figure that once I’ve run the tests, using a spare PC, I’ll be set for quite a while.

Basically I don’t expect to burn that many DVDs (its really just a secondary backup, with an external HDD as my primary backup) so 4 or so cakeboxes there should see me right for maybe a couple of years, maybe longer.

On the CD front, I’m expecting to archive only my irreplaceable discs (the ones that were only ever made in small quantities), which probably means a couple of hundred at most, and almost certainly less. As with DVDs I will be archiving to both optical and HDD to add some fail-safe.

So, given that I don’t anticipate needing to test any more media beyond my initial batches of CD-R, MCC 004 DVD+R and perhaps TY02 DVD+R, I don’t mind spending a few hours now to get things optimised. Plus it is on a spare PC that I will check every half an hour or so, to see if a test is finished.

Re the HDD side of the archive, I had thought about looking into RAID 1 but given that I will have 2 backups anyway decided against it for now. But, out of interest, do you know roughly hoe much a (nearly) silent RAID 1 setup would cost these days please btspm? I don’t like noisy equipment. Actually, I was surprised just how noisy the DVD recorder is. My old Freecom CD recorder is much quieter. I would have thought that drive motor technology would have moved on more than it has.

The drive itself does not appear to run hot and good point about fluctuations in temperatures that I cannot deal with anyway. One other option I was considering was to start burning and testing only after playing a CD for say 10 minutes to warm the drive up. I’m simply looking for as consistent conditions as possible, concurrent with relatively minimal hassle.

Anyway, time to start burning :smiley: