48x CD-RW Combo Roundup Vol.1 - Page 8

DVD Error Correction Tests

Optorite DC4801

In the following tests we examined the DVD error correction capabilities of the Optorite DC4801. For the tests we used CDVD Benchmark v1.21 and Nero CDSpeed . The reference test media comes from ALMEDIO.

- Single Layer media

ABEX TDR-821

This is a single-sided, single-layer DVD-ROM of 4.7GB capacity, in which there are scratches of dimensions 0.4 to 3.0 mm. The following transfer rate picture comes from CDVD Benchmark v1.21.

The drive read the disc normally from the begginning of the disc until sector 1.000.000, where the scratched area became large enough to be able to continue reading at maximum speed. The drive slowed down and finished reading at a speed lower than 8x. However, no read errors were reported.

ABEX TDR-825

This is also a single sided, single layer DVD-ROM with a 4.7GB capacity. The data structure of the disc is exactly the same as the TDR-821, with the difference that there not scratches on it but defected areas with dimensions from 0.5 to 1.1 mm. There also fingerprints sized from 65 to 75 micro meters.

The drive didn't have any problems to read the disc contents. Optorite DC4801 read the disc under the CAV mode until the end of the disc and reached the maximum read of 16X. The test was completed succesfully and no read errors occured.

- Dual Layer media

ABEX TDR-841

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

This time the scratched areas of both layers were read flawlessly. The Optorite drive had no problem to finish the ABEX 841 test with no reading errors. Although the scratched areas are the same as in the case of the ABEX 821 test disc (single layer), the drive did not slow down and gave the maximum supported read of 8X by the end of each layer.

ABEX TDR-845

The disc is a single sided, dual layer DVD-ROM disc with 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 are ranged from 0.5 to 1.1 mm and the fingerprints are sized from 65 to 75 micro meters.

Optorite DC4801 finished and this test without read errors. The disc was read a normal dual layer DVD-ROM disc at 8X CAV.

ABEX TDV-541

The TDV-541 is a single sided, dual layer DVD-VIDEO disc, with capacity of 7.91GB. 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 correction capabilities of the drive and includes scratches from 0.4 to 3.0 mm.

The drive had reading problems in the second layer of the disc. The reading speed was reduced down to 3X and reached the 1X in the inner part of the disc. It seems that the drive could not read the scratched areas of the second layer only, and this is also confirmed by the increased seek times reported.

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.

This time, the defects on the disc surface did not cause reading problems and both layers were read easily at 7X CAV reading speed.