Nero CD-DVD speed scan variance?

I was curious if it’s possible to get varying scan results from the same disc (in the same drive, using the same settings, on the same date) using the extra > disc quality test? I recently made some scans of some DVDs I had recorded and was getting quality scores that were 0 then if I scanned again without ejecting would then get something like 35, and some that were coming in on the first scan as like 42 then jumping up on the second scan to 82. If it weren’t for the large variance I wouldn’t be concerned. And none that scanned at lower than 90 the first time came in at above 90 the second or subsequent times… is this normal?


Possibly, what drive are you using to scan & what types of media? Some example scans would be useful :slight_smile:

I found the answer here I guess when i searched yesterday i couldn’t find it because i didn’t have the right keywords. scroll down to post #4


What [B]rdgrimes[/B] posted is correct, but it may not be what is causing the large scanning variance in your drive. Without some details of what drive you have (posting some example scans would be most useful) and the media you are using, it isn’t certain that is the source of what you are experiencing.

This couldn’t be stressed enough. :iagree:

Maybe you still think, [B]beguiled[/B], that the errors reported are on the disc, and that the app and drive just “reports” them. It’s actually far more complicated than this, as these errors are reading errors (i.e. generated during the scanning process and not “analysed” from the disc), and the first important variable is [I]the scanning drive[/I].

If you’re trying to scan with a NEC or a PIONEER drive, don’t look further. :bigsmile:

LOL guys. I’m working on uploading the pics from some of the scans. it’s even happening with ty’s that I burned that seem to work fine on the standalone player (a ps2). Also, is there any sort of guide as to what are acceptable PIF (max, avg, total) and Quality scores for a “good disc” backup???

ok here are a few:
<li>Family Guy

Some of my TYs are scanning well below QS=90. But they are able to be played, AND even copied from. I was able to copy form Othello with the QS=0 to a disk that when scanned QS=65. What the heck? <li>So what do the scans really show? <li>The quality of the burn? <li>The quality of the disc during playback? <li>Whether the disc will play on a standalone player?<P>I guess I was confused as to what the CDspeed disc quality test was supposed to prove…

here is a scan from my TY disc with a QS<90 that seems to work just fine in our player. What am I looking at here??? Oh, and p.s. This one scanned at QS=62 the first time (but I forgot to copy the file)…

For better consistency and accuracy in the scans, you should turn off ‘quick scan’. Also, when scanning at maximum speed there can often be quite a bit larger variation from scan to scan in comparison to the variation in slower scan speeds. Also keep in mind that standalone playback is done at very slow speeds, and scanning/reading at maximum speed can often show issues that may or may not effect playback at slower speeds. At the end of the day, only testing in the intended device will prove with certainty whether or not it will work fine. Scanning is very useful, but until you understand how they work a little bit better you would be better served with Transfer Rate Testing.

<LI>Transfer Rate Testing? What does that show?
<LI>And at what speed “should” i be testing at?

Thanks for the advice of turning off quick scan. I didn’t even know it was on or what it did, necessarily. Obviously, a Nooob, right? LOL.

<LI>What “should” I be looking for???

My standalone is a PS2, an old XBOX, and an XBOX360. All of them seem to read most recordables fine (given they are on name brand discs). I also watch movies on my computer with a HL-DT-ST DVDRRW (which I read is a pretty standard comes-with-the-machine drive). None of these let me do the quality scans so I have to do them all on the BENQ that I use to burn the discs with.

I’ve had problems with skipping or drives just saying that the media isn’t readable at some point (which was lessened by stripping and trying not to compress over 75% as well as using better media like the TY’s and some others that were on a list of quality media ID’s from, i.e. sony & verbatim).

I admit I haven’t watched ALL the movies that I’ve backed up (sometimes I backup a bunch in a day and watch them later so half the time I wont know if I have a bad copy until months later (which isn’t an issue since I can just go reburn the original but it’s frustrating to find out after the fact – i guess i’m a bit anal). Plus, if it’s a media thing then I guess I want to know now rather than buy more of a bad brand/media ID.

<LI> So, as a newbie, making home backups of movies in our collection, is there any guidelines/testing proceedures I can do on the newly burned discs (other than watch them all the way through on the standalone) to tell if my backups have a greater chance of working on the standalones? (other than not compressing too much and stripping audio? and encoding to and .iso rather than directly to the disc?) Maybe such as burning at lower than max speed? or something???

God! I annoy myself with my newbiness! :flower:

Transfer Rate Tests read the data off of the disc, and show how quickly that they’re able to do so. Ideally there will be no slowdowns and it will show a nice, straight line. As long as the test does not fail, that means that the disc’s data is completely readable in that drive. As I said, a perfect TRT (transfer rate test) is ideal, but a perfect TRT does not necessarily identify a disc that will read back properly in another device, and some slowdowns don’t necessarily identify a disc that will have problems playing back in another drive or at slow speeds. As I said in my last post, ultimately the only test for certainty is testing in the exact application, such as playing back in the intended player. Obviously a good TRT increases the odds of success in other devices, and a poor TRT raises the chances for problems.

Regarding speed to perform a ‘quality scan’ at, there is no real right or wrong, it’s up to the user to decide what they want to get out of their scans. An ideal scenario would probably be to test at both a slower speed and at a high speed, but of course that gets time consuming. There are forum standards here, which is typically 4x or 8x depending on the burner. Benq drives use 8x as a ‘standard’, so scanning at 8x would give the most appropriate scans for comparing to scans posted on CDFreaks from other users. But there is no perfect ‘all in one’ speed or perfect test.

Bad, [B]bad idea to use “quick scan” with Benq drives[/B]. :disagree:
Liteys and NECs are OK with it, but the Benqs react very strangely to it, don’t know why (it’s been bugging me for some time, because for checking disc degradation, quick scan is handy).

Please re-scan, for instance the first two posted discs, with “quick scan” unchecked. If you don’t mind, set the speed to @12X instead of “maximum”, to rule out a possible inconsistency of your unit @16X scanning. :slight_smile: