NEC ND-6500A - Page 4

DVD Error Correction Tests

In the following tests we examined the DVD reading capabilities of the NEC ND-6500A drive with scratched / defective DVD media. For the tests, we used CDVD Benchmark 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, 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 ND-6500A managed to complete this operation without errors. It did not even need to lower its speed to read over the scratched area. Very good performance.

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 it but instead, defective areas of dimensions ranging from 0.5 to 1.1 mm. There are also fingerprints sized from 65 to 75 micrometers.

Again, the clean, straight line indicates very good DVD error correction capabilities, since no errors were reported throughout the reading process.

- 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.

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The NEC drive read the scratched media without problems, as if there were no scratches at all.

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 defective areas and fingerprints. The dimensions of the defective areas range from 0.5 to 1.1 mm and the fingerprints are sized from 65 to 75 micrometers.

Once more, excellent performance from NEC at this point.

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 from 0.4 to 3.0 mm.

The ND-6500A read this test disc as if there were no scrathes on it. Usually, NEC based drives lowered their speed after the layer break-point, but in this case, there were no speed drops reported. It started to read at a speed of 1.90X, reached a highest reading speed of 4.56X at the end of the first layer, and reported an average speed of 3.42X.

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 meter fingerprints.

Not even this disc was a problem for the ND-6500A model.

- Summary

Although CD error correction was not a strong point of the ND-6500A, it seems to perform extremely well with defective/scratched DVD media. High DVD error correction capabilities from NEC.