Plextor PX-712UF Installation And User Manual page 71

4. To begin measurement, in the PI/PO Test window, click the Start
button. You see the error counts representing the result of PI error
measurement and POF error measurement.
5. To end measurement, click the Stop button, or wait for the
measurement to stop by itself. Your window shows the test results,
and a graph of the error counts recorded by the application.
What the PI/PO Measurements Mean
This test measures the quality of the written or pressed media by
counting the number of low-level errors. Most of these errors are
correctable by the drive.
PI/PO is basically the DVD equivalent of C1/C2 error measurement for
a CD. PI indicates the number of bytes that are corrected during PI
stage, while POF indicates the number of uncorrectable blocks. Each
sector on a DVD disc has 2,366 bytes of data. For error correction on a
DVD, the drive places 16 sectors of data into a series of rows and
columns that form an error correction (ECC) matrix. The drive checks
the rows of the matrix for "parity inner," or PI; and it checks the
columns for "parity outer fails," or POF.
The existence of PI errors on a DVD is perfectly normal, since they can
be corrected by the drive's CIRC logic. However, these numbers should
not be too high, because they can create uncorrectable errors when the
disc's playability decreases (for instance, because of dust, fingerprints,
scratches, etc). With POF errors, there is a chance that the data will
become unreadable.
Section 4. Advanced Features and PlexTools Professional
PX-712UF Installation and Users Manual
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