The 5x NEC test "standard"

vbimport

#1

Many, if not most of you use 5x for testing PIE and PIF. If you go higher, the burner introduces more jitter\reader related errors, which makes testing write quality less accurate.

OK, so let’s say I tested my DVD at 5x and it had above average PIE\PIF scores. Does this equate into a successful burn? Yes, if we’re basing judgement entirely on laser-to-dye quality, but wouldn’t it be interesting to know how well the disc reads under normal operation? What if your burner has trouble reading the end of the disc at 16x due to high jitter levels, which were undetectable at 5x? Would you still be happy with a disc that scored well on the 5x test, but performs like one that didn’t?

Perhaps some of you should consider including a max speed result the next time you submit your test results.


#2

I do all my scanning on my NEC ND-3520A at 8x. Same for my BenQ DW1620 Pro.

Regards,
TerminalVeloCD


#3

What I said also applies at 8x speed, since 8x is only half of your drive’s max reading speed. 16x introduces major issues for some media, particularly cheap and slow rated media, which means that those using this site as a resource for media\writer combinations may get misled into buying a media\writer combo that really isn’t nearly as good as the 5x and 8x test results show.


#4

Tests should be made only at 4x.


#5

What I’ve seen so far with my drive is that scanning at 12x produces less PIE/PIF errors than scanning at 5x and the PIE/PIF graph is more ‘even’.


#6

Fr4nz, you’re not following me.

4x is FINE for testing burn quality, but my critique isn’t about burn quality. My critique is that many of the drives being tested at low speeds operate at 16x, which means that normal operating conditions are being left ignored. This leads to a false sense of security. Many readers will automatically assume that when a particular media scores well at low speeds, it will perform well in their 16x drives. This couldn’t be further from the truth.

There are many examples of media with low error rates at lower speeds, but what we don’t know enough about is which of these media struggle with errors and reading at 16x.


#7

Try 16x on media other than Verbatim and TY. Try a batch of G04, or one of the cheaper alternatives. If some media can read fine at low speeds, but struggles at 16x, I believe this is something that users would want to know about before spending their money. Such information should be a no brainer for a group of people whose hobby is staring at graphs all day :wink:


#8

When you look around the forum, you’ll notice that most quality tests not only consist of a PIE/PIF scan, but also a transfer rate test. This transfer test is always done at maximum reading speed. So, basically, you have come up with a method of testing the majority of the community is already using. :slight_smile:

BTW, I doubt if the NEC forum is the right place for this subject.


#9

Why and where is the writen law that says so? For a true representaion the test should be done at 1X as that was the original design standard but who could be arsed to sit though that?


#10

Check the media forum and you’ll find why.


#11

perhaps on a burner that supports 4x… which includes liteon pretty much.
the reason liteons need to be scanned at 4x is that they are 1 ecc under low cpu usage situations ranging to 8ecc in high cpu usage situations.

NEC and Benq do not. NEC is able to scan at ecc1-ecc8 (benq is 8 )
NEC scan speeds are 5 8 13 and 16

all of this is covered in the scanning forum where this thread should be.


#12

And just why isn’t this the right place? I’m a 35xx user who specifically chose this forum because I wanted feedback from fellow 35xx\NEC users. The drive I used for testing was an NEC, and am only interested in feedback from those who use a drive with similar burn strategies, speed, and level of jitter mine has. I am not interested in feedback from those whose drives don’t share these characteristics.

This transfer test is always done at maximum reading speed. So, basically, you have come up with a method of testing the majority of the community is already using. :slight_smile:
Always?

http://club.cdfreaks.com/showthread.php?t=134047

On the first page alone, there are 4 transfer tests that were taken below max reading speed. Furthermore, a sampling of the first 5 pages produced some interesting results:

Testers: 37
35xx max speed tests: 8

This is exactly why I started this thread. We have all of these 5x and 8x tests, but no clue as to how these media performed under normal operation. Tested at 16x, satisfaction would turn to disappointment in many cases.

Please keep in mind that this is meant as constructive criticism, not flame bait. The more informed we are – the better.


#13

Just thought I’d be the first to throw in a maximum speed reading :slight_smile:

Not bad methinks.


#14

I don’t completely agree with that. The topic is about testing in general, so IMO the thread should be in the “DVD Media Testing” subforum. If your critisism is really meant to be constructive (not that I doubt that), then why not let the owners of other drives benefit from it? All of this definitively applies to them as well.

Finally I understand what you mean.

I think you’re not making a clear enough distinction between PIE/PIF testing and transfer rate testing. I took a look at the first 75 posts, but what caught my attention was that most people just posted their PIE/PIF scans (which must be performed at low speed). Only a few added a high speed transfer rate test to their post.

Maybe people got a bit carried away by that long-awaited, exciting, brand new PIE/PIF scanning feature and forgot the importance of a good old transfer rate test. If my memory serves me correctly, Dee once posted in one of the L&D Mod.fw. threads that a test isn’t complete without a transfer rate test, but apparently a lot of people missed that post.

If this is what you mean (there has been quite some miscommunication so far), then I fully agree with you.


#15

If a burner had trouble reading at 16X would it not simply slow down to a speed at which it could read ? failing only if it could NOT read at all

When dealing with Movies would it not make sense to test at 1X ? My uderstanding is that 1X is the speed at which a DVD has to operate to play a movie or am I wrong ? Testing at 16X or Max ( not always the same) tells us what ?


#16

I have to agree, moved to media forum with revised thread title.


#17

Congrats, TommyCP.

As for my response to your post and others, I deleted it. I’m through wasting my time trying to help children.


#18

and for that michael jackson thanks you!


#19

I totally agree with what you have said. Many people, however, may not be aware that scanning with many LiteOn DVD writers at 4X will generate higher PIE/PIF counts than other speeds.


#20

Actually testing at anything above 0x will test also the drive, and not just the disc.

The dvd disc is a rotational medium.

It needs to be spun when read (excluding off-line electromicroscopy scanners for now).

However, the more you spin it, the more you get RF jitter.

RF jitter is what causes PIE/PIF/POE/POF errors when the signal is being read back.

So, the amount of errors will vary as a function of read (rotation) speed (and drive): more speed almost always equals more read errors.

So, what is the optimal speed to test at?

If you want to stress the quality of the disc more than the reader, then the lowest speed is theoretically the best.

However, as pointed out, that doesn’t take everyday use into consideration.

In everyday use, discs are being read back from anywhere between 4x to 16x (depending on drive, settings, firmware, disc and which part of the disc is being read).

So, ideally, to test for worst case REAL LIFE compliance, discs should be tested at 16x.

However, that doesn’t take into account the fact that the higher the read speed, the more drive/reader dependent the score is.

So, while one drive might be able to read the disc at 16x ok, another might fail utterly so.

Is that disc then good or bad? How is the burn quality?

One scan with one drive cannot prove anything about the general burn quality. Just compatibility with that one drive.

Also, again scanning at slower speeds doesn’t stress eccentricity issues so much as as scanning at higher speeds. The rising mountain type of read error graphs is most of the time related to disc eccentricity issues and the drives inability to cope with it.

So, to sum it up:

There is no one right speed to do quality scans at (theoretically and practically), but for practical purposes it is useful to standardise on ONE speed, rather than getting wildly varying speeds from everyone (making the rough comparisons between scans even more impossible).

At CD Freaks the recommendation has been 4x (or sometimes higher for some other models, if 4x isn’t doable).

However, this does not mean that scans at other speeds are worthless. It’s just a way of standardising the scans at one speed, rather than getting different speeds scans from different people.

regards,
Halcyon

PS My personal opinion is that a good disc (i.e. a mechanically properly constructed/non-eccentric/evenly thick disc, with nice optical characteristics, no birefringence, no dye or sputtering unevennes and good burn definition) will scan with low error rates in ALL drives regardless of the scan speed. However, consumer dvd burning isn’t that good yet. Therefor it’s usually more practical to talk about average everyday disc compatibility (i.e. reads back at 4x in various drives) than ultimate burn/disc quality (reads back at 16x in EVERY drive).