Error Correction

In this section, we try to simulate one of the most interesting problems an average user frequently faces while using a DVD player, namely the reading accuracy of a DVD player when accessing a defective or scratched DVD or CD. The performance of the drive here may be influenced by the quality/precision of its mechanical parts (Optical Pickup Unit, sufficient servo control, etc), as well as with the drive's reading strategy under abnormal conditions, controlled by the main chipset and firmware commands. We tested the NeuNeo DV308 with a number of pressed DVD-Video and AudioCD test discs. The ABEX series from Almedio offers a good picture of a CD/DVD reader's error correction capabilities. In addition, we used the SBC444A test disc from Philips and CD-Check test disc from Digital Recordings.

DVD-Video

• Abex TCD-545

This is a single-sided, dual layer (S-2 type, OTP) disc with 8.5GB capacity. The disc can be used for checking the layer switching operation from layer1 to layer 0. The disc also includes test pictures and test signals for Dolby Digital , linear PCM (48kHz/24bit, 96kHz/24bit) and others, to examine high quality pictures and sound. The disc content is an MPEG-2 NTSC DVD-Video file. The TCD-545 includes defects on the disc area (black dots and fingerprints). The size of the black dots varies from 0.4mm to 1.0mm and fingerprints from 0.065mm to 0.075mm.

The NeuNeo DV308 read the disc without skips, picture stills or glitches. This is good behavior since this is prominent problem amongst most PC DVD recorders/players.

• Abex TCD-541

This disc is exactly the same as the Abex TCD-545 tested previously, except that the defect is a scratch ranging in size from 0.4mm to 3.0mm, increasing by 0.2mm /per step. The DV308 showed very good performance again. All chapters of the DVD-Video were played correctly. Here we should say that not all PC DVD/CD players are able to read this specific test disc.

AudioCD

• Abex TCD-726

This is an AudioCD disc used for measurement and adjustment of the error correction capability and tracking/focusing of the servo characteristics of a player against possible defects on some CDs. Three kinds of defects are included on this disc: interruption in information layer, black dots and fingerprints. The interruptions are fabricated by intentionally varying the lengths of pits on the disc fabrication area. Their size varies from 0.5mm to 1.0mm. The diameter of black dots is from 0.4mm to 1.0mm. The simulated fingerprints are in turn, small gathered dots, of diameters sized from 65 micrometers to 75 micrometers. 160 black dots together construct an artificial fingerprint.

All audio tracks were played successfully by the NeuNeo player while no audible read errors (clicks, skips) were noticed.

• Philips SBC 444A

The test concept with the Philips SBC 44A is the same as in the previous test disc. Interruptions on the information layer vary from 400 micrometers to 1000 micrometers, while black dots have size of 300 micrometers to 800 micrometers. This disc is not too difficult for players to read and the DV308 read it accurately.

• Abex TCD-721R

The medium has the same contents as the Abex TCD-726 but with a different defect - a scratch sized from 0.4mm to 3.0mm on the disc's surface. Error symptoms expected when playing this disc are noise, sound skips, same sector repeatedly played, start of tune cannot be detected, etc.

Only the first 6 tracks of this CD played without clicks or skips. The specific track has an artificial scratch sized at 1.2mm. The rest of the tracks, even the last with a 3.0mm scratch, reported few clicks or skips. According to this performance the drive has average error correction.

• CD-Check

We finish this testing cycle with the CD-Check disc from Digital Recordings. Five audio signals (5 tracks) are combined with disc error patterns to rate the player's ability to read and reproduce music completely. The five tracks contain a sequence of tests of progressively rising difficulty .

Check level 1 (track 1): Standard manufacturing errors

Check level 2 (track 2): 0.375mm scratch

Check level 3 (track 3): 0.750mm scratch

Check level 4 (track 4): 1.125mm scratch

Check level 5 (track 5): 1.500mm scratch

Any clicks, interruptions or looping during audio reproduction indicate failure of a Check level (audio track). Below you can see the test results:

The NeuNeo DV308 played flawlessly the first 2 tracks, which correspond to a scratch up to 0.750mm at the end of the track. The last 3 tracks presented a problem for the player. However we should mention that many players, even PC drives, cannot read the past the fourth or the fifth track on this disc.

Summarizing, we can say that the DV308 performed well in our error correction tests. However its performance with the ABEX TCD-721R could be better.