PI Error Scanning --> Slower = More Accurate in General?

vbimport

#1

I know that there are different scanning speeds recommended for different
drives (e.g. 8x for BenQ, 5x for NEC, etc.).

But is it safe to say in general that slower scanning speeds tend to give more
exact results ? In other words: could a slow scanning speed produce worse
(less exact) results than a faster one ?

Is a choosing a slow scanning speed (4x) the safe thing to do when in doubt
about a certain drive’s peculiarities ?

Thanks.
Raynor


#2

Hi,

In my opinion: no.

Is a choosing a slow scanning speed (4x) the safe thing to do when in doubt about a certain drive’s peculiarities ?
There are some users, that scan at high speeds in order to reveal weaknesses of the disc. Also, a good scan does not automatically mean that your burn is a good one. That’s why it should be accompanied by a read test like the “benchmark” test in CD/DVD Speed.

If you are interested in further details, then check this article at first: http://www.cdfreaks.com/reviews/Home-PI_PIF-scanning---Who-to-believe

Michael


#3

No, but less variable scans as a general rule.

In other words: could a slow scanning speed produce worse (less exact) results than a faster one ?
There’s really no such thing as an “exact” result if you’re thinking in terms of some value that is objectively correct for a disc. This is because PIE and PIF are measurements of how the disc and drive interact, and it’s meaningless to try to remove the drive from that interaction.

That being said, scanning at slower speeds will tend to produce less variable results on the same drive and between drives of the same type, while scanning at higher speeds tend to magnify differences between drives, between discs, and between scans of the same disc in the same drive.

This makes slower scanning speeds better for comparing your own scans with scans performed by other people in other drives.

For the same exact reason, this makes faster scanning speeds better in terms of discovering problems that might not be seen at slower scanning speeds!

So both fast and slow scanning have their own advantages and disadvantages, but neither is more “exact” than the other in an objective sense.

@raynor: Welcome to CDFreaks! :slight_smile:


#4

Thank you for your replies.

So I guess that for the sake of comparison, I’ll stick to 4x speed.

The thing is that when scanning with my Samsung 182D, the results look comparable
to results that are posted by other people when using 4x speed whereas that is not
the case when using 8x or higher.

Example: A nicely burned disc (from which I know that it is a very nice
burn) shows up nicely when using 4x speed, but the results with 8x seem
to be off a little bit in the beginning (too high).

What do you think is more likely:
a) The result at 8x is due to the peculiarities of the scanning drive (my guess)
b) The result at 8x points to “a problem that might not be seen at slower
scanning speeds”
(which would certainly only be a slight one)

Attachments: 2 scans of the same disc (MCC 004 burned @ 8x in the
venerable NEC-3500A) Once scanned with 8x, the other time with 4x.




#5

How do you know that it’s a very nice burn? :confused:
Do you have some sort of super powers like X-ray vision, which makes this possible without looking at the scans? :bigsmile:

a) and b) are both possible explanations. Looking only at those scans makes it impossible to say which is the right explanation - it could even be a combination of the two.

Much more testing of the scanning drive is needed to know which explanation is more likely to be right.


#6

How do you know that it’s a very nice burn? :confused:
Do you have some sort of super powers like X-ray vision, which makes this possible without looking at the scans? :bigsmile:

OK, sorry, I should have rather said that I strongly guessed that it
"simply had to be" a good burn due to the past exellent results I got
with my NEC-3500 and MCC004 media. Of yourse, there is no way of
being sure about that :wink:

Much more testing of the scanning drive is needed to know which explanation is more likely to be right.

You are right, I’ll be off conducting many more tests, thx for now :bigsmile: