DVD Error Correction Tests

The following tests examine the DVD reading capabilities of the Optorite DD0401 drive with scratched and defective DVD media. For the tests we used CDVD Benchmark and Nero CDSpeed. The reference test media came from ALMEDIO.

- Single Layer media

ABEX TDR-821

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

The Optorite DD0401 read the 821 test disc without reporting any read errors. The yellow dots indicate that the drive returned different reading speeds for each read retry, as a result of the scratched areas. The disc was read accurately at 12x CAV.

ABEX TDR-825

This is also a single sided, single layer DVD-ROM of 4.7GB capacity. The data structure of the disc is exactly the same as that of the TDR-821, with the difference that instead of scratches, there are defective areas of dimensions ranging from 0.5 to 1.1 mm. There are also fingerprints sized between 65 and 75 micrometres.

As in the previous test, no read errors occured with this disc. The drive read the disc with CAV mode but did not manage to reach the maximum reading speed of 12x. The difficult areas on the specific disc seem to be the artificial fingerprints, where the drive slowed down to 11x CAV in order to complete the test .

- Dual Layer media

ABEX TDR-841

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

Reading of the dual layer DVD-ROM disc produced some interesting results. As can be seen from the graph above, the result is not a continuous ascending line indicating CAV reading from beginning to end, but instead the speed dropped to around 4x where it appears to have gone into CLV reading. The drive did manage to read both layers with some difficulty though, especially towards the end, and did not surpass 7x reading speed althoughand it finished the test without posting any read errors.

ABEX TDR-845

The TDR-845 test disc is a single sided, dual layer DVD-ROM disc with a capacity of 8.5GB. The difference between the TDR-845 and the TDR-841 test disc used in the previous test, is that the TDR-845 includes defective areas and fingerprints. The dimensions of the defective areas range from 0.5 to 1.1 mm and the fingerprints have a height of 65 to 75 micrometres.

The first layer was read intact. The second layer however, produced similar results to the test to those of the TDR-841 disc, where reading dropped speed and continued at a constant velocity.

ABEX TDV-541

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

The results are presented above as 2 alternating screen shots. The drive initially returned a "NO SEEK COMPLETE" error message. The test was run a second time and again returned the same result. The DVD was then viewed with PowerDVD and played without any visible problems. We ran the test a third time and the result is the second of the screen shots from above. The 3rd test completed without errors but it is evident that the drive had difficulty.

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 also has 65 - 75 micrometre fingerprints.

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