What you are observing is perfectly normal.
PIE/PIF/POE/POF errors are not on the disk.
They are read errors, made by the drive, when it tries to read that data off the disk.
The errors themselves are not on the disk.
Consider the following analogy, to understand the situation:
DVD-disc = a piece of paper
dvd burner = a pen
dvd reader (scanning drive ) = a reader
When somebody writes on a really bad piece of paper, the text may be all there 100% error-free, but readers will make more errors when reading the text from really smudgy paper.
These are read errors.
Some readers are just much better at reading text written with bad quality or on really bad quality paper.
Those readers make much less errors, when reading back bad writing.
The same applies for dvd scanning.
Bad burner or bad disc will result in a bad burn quality.
However, this burn quality does not results in bit-level errors on the disc.
It results in (using the analogy again here) smudged out inscription, which is hard to read.
Now, reading this hard-to-read smudgy inscription results in read errors.
Those are errors that are made by the reader, because the inscription is fuzzy.
Do you understand the difference?
Burn quality = inaccurate, variable and out-of-spec modulation of dye-characteristics on the burned dvd disc
Read quality = number of errors made by the scanning drive, when reading back a disc with a certain level of burn quality
Now, the second question:
Why are readers so different in reading back discs?
Why some drives make more errors than others, when reading back discs with marginal burn quality?
This is a difficult question to answer exhaustively (I'm not sure I even know all the variables).
However, the following properties determine the reader's ability to read back discs error free:
- amount of money used on parts (cheaper can often be worse, but not always)
- amount of time spent on optimizing read capabilities (instead of writing capabilities of drives)
- skill of the dvd design team, availalable testing resources & equipment
However, regardless of what causes it, it is a know fact that some DVD readers are better readers than others.
Hence, they report back lower number of read errors (PIE/PIF/POE/POF).
This is why consumer grade read errors should NEVER be used as a measure of GENERAL disc quality.
A consumer read error DVD scan is always a measure of disc compatibility with the drive doing the scanning.
One can generalize a bit further, by using several different readers (Plextor, LiteOn, BenQ, etc) to scan the same disc, statistically analyze the results and then deduce something from the results.
However, this requires much more scanning and the results are not self-evident.
That is, it is NOT safe to assuma that if PIE/8ECC<280 that the disc is "good" or that if PIF/1ECC > 4 that the disc is bad.
One must use these as a relative measures only.
The numbers reported by different drives are not comparable which each other, not only because the drives are of different reading quality, but because they report different units!
For example, LiteOns report:
- PIE as a sum of 8 consecutive ECC blocks (floating 8ECC window)
- PIF from each 1 ECC block
- PIE as a sum of 8 consecutive ECC blocks (adjacent non-floating 8ECC block groups)
- PIF from each 8 consecutive ECC blocks (adjacent non-floating 8ECC block groups)
- PIE as a sum of 32 or 64 consecutive ECC blocks (adjacent, non-floating)
- PIF for each group of 32 or 64 consecutive ECC blocks (adjacent, non-floating)
As you can see, the type of reporting is different, so are the units. As such, they are not comparable.
I hope this explains some of the background why:
- dvd scan results vary depending on the drive used
- why there are differences
- why one should never compare results from two different drives
- why one should NOT read the results as absolute values (but as relative measures)
- who one should NOT trust any one single reader to provide accurate information about what kind of quality a certain disc is
The overall situation is a little bit more convoluted, but I hope I was able to summarise the situation above in a simplified form.