Testbed and Methods

We took a Lite-On SOHW-1653S (firmware revision CS09) as our etalon of an optical drive. We made this choice basing on the fact that drives from Lite-On are widely available on the market, under Lite-On’s own brand as well as under other company’s badges. For example, the SOHW-1653S is in fact identical to such models as Lite-On SOHW-1633S, Sony DW-U22A, and Teac DV-W516A. Another reason for our choosing this Lite-On for this test session was the compatibility of this drive with Nero CD-DVD Speed. The KProbe utility that we use for scanning the surface of the written disc also supports Lite-On’s drives. Of course, high-quality burning comes as the result of a harmonious combination of a drive and a disc, but we will be evaluating the quality of the tested discs basing on their performance in one particular drive due to the above-explained reasons. We use two programs to scan the written DVDs to obtain objective results and also to understand their operation better with more media and to ultimately answer the question which program is more efficient and correct.

So, we copied a DVD Video movie from its ISO image on the hard disk drive to the tested disc and scanned the disc after that. The configuration of our computer was like follows:

• Intel Bonanza D875PBZ mainboard;
• Intel Pentium 4 2.8GHz CPU;
• IBM DTLA-307015 HDD, 15GB;
• GeForce2 MX400 64MB graphics card;
• 512MB DDR SDRAM;
• Microsoft Windows XP Professional with Service Pack 1 and DirectX 9.0b.

We attached the optical drive to the second IDE channel as “Master”.

The following software was used in the tests:

• Nero Burning ROM version 6.6.0.1
• Nero CD-DVD Speed 3.61
• DVD Identifier 3.6.2
• KProbe 2 version 2.4.2

The DVD-RW/+RW discs were recorded at the maximum speed they are rated for by their manufacturers. If this information was unavailable, we determined it practically, finding the maximum possible speed. The subsequent scanning of the written discs was performed at a constant speed of 4x.

DVD Quality Criteria

Before getting to the tests proper, we want to illumine you on some theoretical aspects concerned with evaluating the quality of DVD discs. We base our judgments about the quality on the data we receive by scanning the recording with the two above-mentioned programs (we should say it first that the numbers may be different with another optical drive). CD-DVD Speed and KProbe evaluate the quality of DVD discs 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. 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.