Error Correction Tests

In the following tests we check the drive's behavior when it comes to reading scratched / defected audio discs. The test discs we use are the ABEX series from ALMEDIO.

- ABEX TCD-721R

Errors total	Num: 115802595
Errors (Loudness) dB(A)	Num: 546383	Avg: -25.2 dB(A)	Max: -4.9 dB(A)
Error Muting Samples	Num: 22790	Avg: 3120.0 Samples	Max: 3584 Samples
Skips Samples	Num: 2	Avg: 698.0 Samples	Max: 698 Samples
Total Test Result	51.0 points (out of 100.0 maximum)

The drive did not manage to correct the severe errors of the ABEX TCD-721R test disc. Both, the amount and the level of the reported errors are high, resulting to a low quality score. On the other hand, the drive starts reporting errors in the expected position and not earlier, meaning that the optics and error correction circuits are tuned adequately. According to EAC author, such level might lead to audible problems in the output signal.

The amount of the muted samples is also very high. This means that the drive will generally play your old audio discs pretty well, unless their physical condition is not as bad as this of the Abex 721R disc. These are first indications about the overall performance of the drive and the following additional tests will help us come up with safer conclusions.

- ABEX TCD-726

Errors total	Num: 0
Errors (Loudness) dB(A)	Num:4	Avg:-94.0 dB(A)	Max: -87.6 dB(A)
Error Muting Samples	Num: 0	Avg: 0.0 Samples	Max: 0 Samples
Skips Samples	Num: 1	Avg: 185.0 Samples	Max: 185 Samples
Total Test Result	83.6 points (out of 100.0 maximum)

Abex TCD-726 is much easier for the drive to read. For this reason, Philips DVDR824P corrected almost all errors and the overall quality score is very high (83.6 points).

- CD-Check Audio Test Disc

The CD-Check Test Disc is a very useful tool for evaluating the Sound Reproduction / Error correction capabilities of a CD player. The disc offers a signal combination with disc error patterns to rate the drive's abilities to read music and reproduce it completely. Five tracks on the disc contain a sequence of progressively difficult tests. These tracks are referred as Check Level-1 through Check Level-5.

The files are reproduced (played) through a software multimedia player (i.e. Windows Media Player). Each level is considered as passed, if the tone coming out from the speakers is smooth, continuous without interruptions, skipping or looping. The higher the Check Level passed, the more reliable the sound reproduction of the tested device.

Error Level	1	2	3	4	5
Philips DVDR824P	5/5	5/5	5/5	5/5	5/5

The drive passed all 5 Check Levels of the test. The performance reveals very good sound reproduction and error correction. The fifth level includes an error size of 1.500mm, and the drive managed to play the file without audible clicks.

The results with the Abex TCD-721R (max scratch size 3,00mm) and CD-Check test show that Philips DVDR824P is tuned to correct errors coming from scratches sized up to 1,500mm approximately.

- Summary

Test Disc	Reading Speed	Score
ABEX TCD-721R	Max	51.0
ABEX TCD-726		83.6
Average Score		67.3

Combining the two scores from the ABEX tests we estimate an average total score of 67.3 points out of 100. This is not the highest score we have ever experienced from a drive, but it does not fully give the image of the drive's performance. Philips DVDR824P managed to read severely scratched discs with a high accuracy, as long as the scratches did not exceed a critical size.