LG GSA-4081B Multi DVD Recorder - Page 5

DVD Error Correction Tests

In the following tests we examined the DVD error correction capabilities of the LG GSA-4081B Multi DVD Recorder. 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 with a 4.7GB capacity, in which there are scratches with dimensions ranging from 2.6 to 4.8 mm. The following transfer rate picture comes from CDVD Benchmark v1.21.

The graph shows that the drive had a few problems reading the disc, especially towards the end. This is a little strange as the defects are located mostly in the first half of the disc.

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 there are no scratches on the surface and instead defective areas ranging in dimensions from 0.5 to 1.1 mm. There are also fingerprints with height between 65 and 75 micrometers.

The resultant graph here is almost the same as the one from the previous test. Once again, the performance is not particularly good and the drive certainly shows problems reading this disc.

- 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 4.8 mm, on both layers.

With this disc, the drive manages to produce a linear speed increase for both layers without any major glitches. The thickness of the lines however indicates the number of attempts required to read each point, while the random dots intersperesed above and below show major speed fluctuations. These fluctuations are common as the drive tries to overcome the defective areas. What is more puzzling is, as was the case with the tests above, that the major problem appears to be in the areas where there are no defects.

ABEX TDR-845

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

Again, there seem to be more problems away from the defective areas, towards the end of each layer. As for the defects, while not the best results we have, seen, the drive seems to bypass defects without any major problems.

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 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 drive shows a major problem when switching to the second layer in this test. Both velocity and reading speed are dramatically affected and it takes quite a while before the drive recovers.

ABEX TDV-545

The TDV-545 disc is based on the TDV-540 series. It is a single sided, dual layer Video/S-2 disc with a capacity of 8.5GB. The TDV-545 includes artificial black dots on the disc's surface, sized from 0.4 to 1.0 mm. It also has 65 - 75 micrometre high fingerprints.

 Black dots and fingerprints were not a problem for the drive. The test was successfully completed, with an average reading speed of 6.14x. It appears that defects are not so much the problem with this drive since in virtually all of this series of tests with defective media, the drive performed admirably over the defective areas. The problems seemed to manifest themselves in regions on the disc's surface where there were no defects, and if there is a pattern, it seems to be that the problem is at the end of the layer or layers.