4x DVD+R/RW Roundup- Page 7

DVD Error Correction Tests

Mitsumi DW-7801

In the following tests we examined the DVD error correction capabilities of Mitsumi DW-7801TE. 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 from 2.6 to 4.8 mm. The following transfer rate picture comes from CDVD Benchmark v1.21.

As you can see from the graph the Mitsumi DW-7801TE had serious problems to read the disc contents, after the 570.000 sector of the ABEX disc. By that point, the scratch on the test disc had a 1.8mm size. The reading speed was reduced to 3x, and read errors were reported. CDVD Benchmark performs multiple readings of the same sector when it is initially found unreadable. The duration of the test was more than 3 hours, and finally the reading process was terminated.

ABEX TDR-825

This is also a single sided, single layer DVD-ROM of a 4.7GB capacity. The data structure of the disc is exactly the same as that of the TDR-821, with a single difference that there are no scratches on it but defected areas with dimensions ranging from 0.5 to 1.1 mm. There are also fingerprints sized from 6.5 to 7.5 mm.

The drive did not have any problems to read the disc contents. The yellow dots correspond to the current speed in each area of the disc. No read errors were reported.

- Dual Layer media

ABEX TDR-841

This is a 8.5GB dual layer, single sided, DVD-ROM disc with artificial scratches of dimensions ranging from 0.4 to 4.8 mm, in both layers.

Since the drive had hard times to read the single layer scratched disc (ABEX TDR-821), the results in the above test were not surprising. Non of the layers was entirely read, and multiple read errors occurred as soon as the size of the scratch was 2mm.

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 0.065 to 0.075 mm.

Although the artificial defects and fingerprints on the TDR-845 test disc, the Mitsumi DW-7801 finished the test without any read errors.

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 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 model checks also the error correction capabilities of the drive and includes scratches from 1.8 to 3 mm.

The drive supports 2-5x CAV average reading speed for the DVD-Video format. Again the test was terminated with a read error, during the first layer.

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 0.8 to 1.0 mm. It has also 0.065 - 0.075 mm fingerprints.

Black dots and fingerprints were not a problem for the drive. The test was successful, with a 3.44x average speed.