DVD Error Correction Tests

Once again, it should be mentioned that the drive is identified as Lite-On DVDRW LDW-811S, and hence the titles appearing at the top of each test graph.

In the following tests we examined the DVD reading capabilities of the Pacific Digital U-30201 drive with scratched / 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 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.

The drive read the 821 test disc without reporting any read errors. Yellow, stray dots indicate that the drive gave back different reading speeds for each reading retry, due to scratches on the media's surface, and here we can see that the drive performed extremely well. The disc was read accurately and exceeded 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 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.

As in the previous test, no read errors occured with this disc. The drive again managed to reach maximum reading speed slightly in excess of 12x CAV.

- 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.

Here too, the drive managed to read both layers without fuss and passed the 8x reading speed for dual layer DVD media.

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 microns (micrometres).

As with all the reading tests for DVD media, this one did not prove to be a problem for the Pacific Digital drive.

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.

Reading the first layer did not prove a problem, with the drive reaching a maximum of just over 8x CAV. The increase in speed is fairly constant and linear, starting at 3.57x and reaching 8.45x by the end of the first layer (outer tracks). The velocity (yellow line on the graph above) also remained fairly constant. The second layer however proved to be a lot more difficult, where at the beginning (outer tracks on the disc's surface), both transfer speed and velocity fluctuated. A little after the 5GB mark reading returned to normal. Since the point of the TDV-541 test disc is to test a drive's ability to switch operation from layer 0 to layer 1, it is evident that the Pacific Digital drive had a few problems.

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.

The drive showed no problems reading this disc.

Continuing our comparison with the LiteOn drive, it is evident that there are some characteristics that are almost identical, such as the TDV 541 test disc where both drives showed the same behaviour when switching layers. On the other hand, the TDV 545 produced no problems on the Pacific Digital drive where we notice a near perfect, linear graph (the same graph for the LiteOn drive produced some problems at the change-over to the second layer). The LiteOn also had a few problems reading the TDR 841 test disc with artificial scratches on the second layer. In general, the Pacific Digital drive appears to give better overall performance with fewer problems on the second layer.