DVD Error Correction Tests

In the following tests we examined the DVD reading capabilities of Plextor PX-708A drive with scratched / defected DVD media. For the tests we used CDVD Benchmark and Nero CDSpeed . The reference test media come from ALMEDIO.

- Single Layer media

ABEX TDR-821

This is a single sided, single layer DVD-ROM with a 4.7GB capacity, and its surface has an artificial scratch of dimensions varying from 0.4 to 3.0 mm. The following transfer rate picture comes from the CDVD Benchmark v1.21 transfer rate test.

Plextor PX-708A read the disc at 12x CAV and the scratched area did not affect the process. The disc was read accurately and no read errors or were reported. The performance reveals high error correction capabilities with scratched single layer DVD-ROM discs.

ABEX TDR-825

This is also a single sided, single layer DVD-ROM of a 4.7GB capacity. The data structure of the disc is exactly the same as that of the TDR-821, with the difference that there are no scratches on it but defected areas of dimensions ranging from 0.5 to 1.1 mm. There are also fingerprints sized between 65 and 75 micrometers.

As in the previous test, the disc was read without any read errors. The reading speed was not reduced when the drive read the defected areas, and the test was finished successfully.

- Dual Layer media

ABEX TDR-841

This is a 8.5GB dual layer, single sided DVD-ROM disc with artificial scratches of dimensions ranging from 0.4 to 3.0mm, in both layers.

The drive gave back uncorrectable read errors in the heavily scratched areas and the reading test was terminated from the first layer of the disc. The results were confirmed through the Windows Explorer since the disc contents were not accessible.

Although the drive finished successfully the ABEX 821 reading test, which has the same scratches for a single layer, it seems to face serious problems with the scratched double layered media.

ABEX TDR-845

The disc is a single sided, dual layer DVD-ROM disc of a capacity of 8.5GB. The only difference between the TDR-845 and the TDR-841 is that the first includes defected areas and fingerprints. The dimensions of the defected areas range from 0.5 to 1.1 mm and the fingerprints are sized from 65 to 75 micro meters.

As in the corresponding test with the ABEX TDR-825 (defected single layer DVD-ROM), the disc was read accurately. The average reading speed for each layer was 6.06x, but the seek times were increased.

According to the results we have gathered until now, Plextor PX-708A can easily read scratched / defected single layer DVD-ROM discs, reads adequately the defected (fingerprints, black dots) dual layer discs, but needs to be improved when it comes to reading dual layer scratched DVD-ROMs.

ABEX TDV-541

The TDV-541 is a single sided, dual layer DVD-VIDEO disc, with a capacity of 8.5GB.The disc is based upon the TDV-540 series which is designed for inspection and adjustment of DVD-VIDEO players. The discs check the layer switch operation from layer 0 to layer 1 and also include test pictures and test signals for DVD sound files. The current TDV-541 checks also the error correcting capabilities of the drive and includes scratches from 0.4 to 3.0 mm.

The reading process started at 3.5x until the 2.0GB address of the test disc, where the drive lowered the speed in order to read the scratched area. Although the first layer was read, not easily however, the second layer was even harder for the drive. CDSpeed gave a read error and the test was terminated, as you can see in the screen shot above.

The test results were confirmed when we tried to play the DVD Video files of the disc in our test PC, with CyberLink PowerDVD software. Playback froze by the end of the first layer (below 4.0GB address), and many skips occurred. We did not manage to playback the rest of the movie (second layer).

ABEX TDV-545

The TDV-545 disc is based on the TDV-540 series. It is a single sided, dual layer DVD-VIDEO disc with a capacity of 8.5GB. The TDV-545 includes artificial black dots on the data surface, sized from 0.4 to 1.0 mm. It has also 65 - 75 micro meters fingerprints.

Black dots and fingerprints on the disc surface did not create any reading problems, and the drive finished the task successfully.