How to tell "good" from "really good" media?

vbimport

#1

I’ve been trying a few different media in my new Sony DRU-800A (with f/w KY04). Some have been not so good (RicohJPNR02, RicohJPNR03, CMC MAG. AM3) while others have been “good” (well under the max 280 PI, max 4 PIF)

But, how to choose among the “good” media?

All 4 were scanned with KProbe 2.4.2 at 4x, ECC 8/1. So:

[ul]
[li]Is it better to have just 6800 total PI but 300 total PIF, or (higher) 120,000 total PI but (lower) just 110 total PIF?
[/li][li]Or, is there any real difference between total PIF of 100 or 200 or 300, or is this just noise once it gets this low?
[/li][/ul]

Disc : DVD-R , MCC 03RG20 [Mitsubishi Chemical Corporation]
Speed : 4x
ECC blocks sum (PI/PIF) : 8/1
Scanned range : 0 - 2280735
Sampling count : 122841
Errors : 0
PI Max : 41
PI Average : 7.08
PI Total : 117370
PIF Max : 2
PIF Average : 0.01
PIF Total : 114

Disc : DVD-R , TYG03 [Taiyo Yuden Company Limited]
Speed : 4x
ECC blocks sum (PI/PIF) : 8/1
Scanned range : 0 - 2280742
Sampling count : 129846
Errors : 0
PI Max : 41
PI Average : 6.88
PI Total : 115036
PIF Max : 2
PIF Average : 0.01
PIF Total : 185

Disc : DVD+R , MCC004 [Mitsubishi Chemical Corporation]
Speed : 4x
ECC blocks sum (PI/PIF) : 8/1
Scanned range : 0 - 2280750
Sampling count : 128793
Errors : 0
PI Max : 208
PI Average : 5.94
PI Total : 99061
PIF Max : 3
PIF Average : 0.02
PIF Total : 260

Disc : DVD+R , YUDEN000T02 [Taiyo Yuden Company Limited]
Speed : 4x
ECC blocks sum (PI/PIF) : 8/1
Scanned range : 0 - 2280745
Sampling count : 130020
Errors : 0
PI Max : 7
PI Average : 0.40
PI Total : 6729
PIF Max : 2
PIF Average : 0.02
PIF Total : 300

One final newbie question: If PIF are “uncorrected” PI errors, why do they not result in data corruption on a data DVD? What corrects the uncorrectable errors?


#2

There are two levels of error correction involved. The first one occurs on a relatively “fine scale” and is known as “inner parity”. The second level operates on a much larger grained scale, less frequent parity blocks but containing very much more parity information per block, this is what is referred to as “outer parity”.

Inner parity should mostly correct incidental read errors but cant handle the sort of multiple errors that a scratch or significant physical defect can produce, this is where outer parity comes into play. Essentually if outer parity is not being invoked very often then your media is in good shape.

BTW, since outer parity is invoked whenever inner parity fails then a PIF (parity inner fail) is basically the same thing as a PO (parity outer) invocation. It’s a parity outer fail that will really cause trouble for your discs readabilty.


#3

To answer your question, all of your scans are very good, and will vary from lot to lot. Some lots of MCC03 may burn better than some lots of Taiyo Yuden, but the differences will be small. I personally only use the medias that you are testing. I would trust any one of them as my backup/restore for my computer (making two seperate backups of course)…


#4

Thanks for a short and clear explanation. I’m used to KProbe’s terminology, but I now see that CDSpeed presents the differences more clearly:

  • PI Errors
  • PI Failures
  • PO Failures
    where only PO Failures cause data loss.

#5

Just to throw my 2 cents in, and have you confused a little :bigsmile: , I’d say that for me the difference between “good” and “very good” MIDs is not found in PI/PIF scans, but in the consistency between batches, climatic stability of the discs, and compatibility with drives…

Hey, uart, I see you’ve done your homework! Very nicely put. :clap: - I have many old TDKG02 discs showing very high (>400) PIE levels but very low PIF levels and they play just fine, when the opposite (in-specs PIE levels but high PIF levels) is much more problematic… :iagree: