DVD Burning Quality Criteria

Before getting to the tests proper, we want to remind you about the criteria we guide ourselves by when evaluating the recorded discs and the drives.  We scan the surface of a disc with two programs – CD-DVD Speed and KProbe – that assess the quality of the disc by counting up the number of PI errors and PI failures.

The ECMA standards for DVD-R/RW and DVD+R/RW media say that the total number of PI errors in 8 subsequent ECC blocks should not exceed 280. This is the first limiting value we will base our judgments upon. A PI error is a row in an ECC block which contains at least one erroneous byte. A row in its turn consists of 182 bytes in which the last ten bytes contain Parity Inner information. Each ECC block contains 208 rows where 16 last rows contain Parity Outer information. So, an ECC block should not contain more than four irrecoverable PI errors (an irrecoverable PI error is referred to as PI failure by KProbe and CD-DVD Speed).

Thus, we consider those DVD discs as quality media that have no more than 280 PI errors and 4 PI failures per one ECC block. The errors of the second type, the irrecoverable ones, are the worst, of course.

This approach to analyzing the test results isn’t perfect, though. In some cases there are just single spikes of errors in a few spots of the disc that exceed the allowable maximum, while the rest of the disc surface is quite perfect. Thus, such a disc might be wrongly considered inferior to a medium where there are much more errors in total but without high spikes above the allowable maximum. So, in order to make your choice correctly, you should examine the screenshots with the surface-scan graphs and look at the total number of the errors or at their average rate. This way you’ll have the fullest picture of the quality of a particular disc.