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Home > Hardware Reviews > Optical Storage > 48x CD-RW

Friday, September 27, 2002
PleXWriter PX-W4824A

4. Error Correction Tests

PleXWriter PX-W4824A IDE CDR-W- Page 4

Error Correction Tests

In the following tests we examine the reading error correction capabilities of the PleXWriter PX-W4824A.

- EAC CD-R Test Disc

- Introduction

We used the testing methodology as described in EAC website. The CD-R test disc includes 5 scratches and a black triangle defect. Using the "c2extract.exe" software and by setting the reading speeds with Nero Drive speed (max & 4X) we ripped the disc. The attached analyse.exe software used to get the necessary results.

The graph tells a lot about the abilities of the drive. The quality of the optical system (and/or of the error correction capabilities of the firmware) is shown in at which time index the error start. The error hiding qualities are shown when the wedge gets bigger.

The grid of the graph has the following means:

  • The X position of a grid line is always a start of a new minute position on the CD (in play time, up to 74 min).
  • The Y axis shows the dB (A) value of the error in the extracted file. dB (A) is a weighting/curve that does not look as much at high and very low frequencies as at medium frequencies, using an A-weighting curve.
  • The graph shows a range of 6 dB (A) down to -120.0 dB (A). Each line represents 6 dB(A) of volume (6 dB(A) louder means that the sound is double as loud)
  • " For the test CD, everything below -60 dB (A) is quite acceptable for error correction. Anything higher than -42 dB (A) is quite critical, and you would hear that in any case. Of course that also depends on the surrounding music/noise. If the rest of the song is absolutely silent, you will probably even hear a -96 dB (A) - only by using 24 bit audio files. If it is hidden in -6 dB music, you will probably not hear -72 dB (A) (or even -66 dB (A) anymore...

- Explanation

After the analyze finishes, we will get a detailed report about the various errors:

- Errors total tells about the total number of wrong stereo samples. This includes areas of wrong samples that may include some correct samples.

- Errors Loudness is the number of FFT analysis done. For that the average and maximum value tells the power difference of the two signals. No acoustic model is used for this calculation, so the audible error may differ from these values.

- Error Muting tells something about error hiding. On bad errors (or bad error hiding techniques), the last error free sample is held for some time until a new valid sample is found. The number of these mutings is given as first result, following the average and maximum sample length of these mutings.

- Skips are occurring when the sync was lost and the drive had to reposition again (and started on a slightly different position). Non-accurate stream devices would loose the sync very often and smaller and bigger skips occur (thus samples are missing or extraneous). The average and maximum values denote the length in samples of such skips.

- Total Score is calculated according to the previous errors. The higher score a drive gets the better!

- Test Results (4X Reading)

The PleXWriter PX-W4824A at 4X got a higher score than max speed. The main reason is that it corrected all the 5 scratches but could not correct the black triangle defect. In that area, the spikes reach the -4.5 dB (A). The drive gets a 70.5 score out of 100 (max).

Errors total
Num: 771492
Errors (Loudness) dB(A)
Num: 4892
Avg:-74.9 dB(A)
Max: -4.5
Error Muting Samples
Num: 1022
Avg: 2.5 Samples
Max: 27
Skips Samples
Num: 14
Avg: 6.0 Samples
Max: 6
Total Test Result
70.5 points (of 100.0 maximum)

- Test Results (Max Reading)

The PX-W4824A, at full speed, starts reporting errors at 16mins. The errors within the black triangle defect, reached -6.0 dB. The five scratches are not repaired as in the 4X reading speed test. The drive gets a score of 69.8, out of 100 (max).

Errors total
Num: 1238512
Errors (Loudness) dB(A)
Num: 8034
Avg: -74.4 dB(A)
Max: -6.0
Error Muting Samples
Num: 1026
Avg: 1.8 Samples
Max: 93
Skips Samples
Num: 11
Avg: 9.8 Samples
Max:48
Total Test Result
69.8 points (of 100.0 maximum)

- ABEX TCD-721R

- Introduction

This test disc includes artificial scratches with lengths from 1.8 mm to 3.0 mm.

Using the ABEX TCD-714 as the reference disc, we created the reference.wav file that is needed for the comparison. Using the c2 extract software and by setting the reading speeds with Nero Drive speed (max & 4X) we ripped the disc. The attached analyse.exe software gave the comparison results. The drive under the 4X reading speed mode, refused to end the task since aborted at 50%. Therefore only the max speed result is showed.

- Test Results (Max speed)

At the maximum reading speed, the drive got a score of 68.1.

Errors total
Num: 14642824
Errors (Loudness) dB(A)
Num: 48717
Avg: -68.6 dB(A)
Max: -9.4
Error Muting Samples
Num: 60753
Avg: 2.4 Samples
Max: 279
Skips Samples
Num: 2
Avg: 6.0 Samples
Max: 6
Total Test Result
68.1 points (of 100.0 maximum)

- ABEX TCD-726

- Introduction

The ABEX TCD-726 includes three kinds of defects, interruption, black dots and fingerprints. The interruption defects are sized from 0.5 mm to 1.0 mm. The black dots are from 0.4 mm to 1.0 mm and the fingerprints range from 65 to 75 micro meters.

- Test Results (4X Speed)

At 4X reading speed, the drive showed a very good behaviour. The only two spikes gave the drive a score of 80.9 out of 100 (max).

Errors total
Num: 368
Errors (Loudness) dB(A)
Num: 15
Avg:-76.4 dB(A)
Max: -23.7
Error Muting Samples
Num: 0
Avg: 0.0 Samples
Max: 0
Skips Samples
Num: 1
Avg: 408.0 Samples
Max: 408
Total Test Result
80.9 points (of 100.0 maximum)

- Test Results (Max Speed)

At the maximum reading speed, errors occurred at the same positions as in the 4X reading speed test. However the drive now gets a higher score of 81.5 out of 100 (max), since the average loudness reaches -72.5dB compared to the -76.4dB in the 4X reading speed.

Errors total
Num: 312
Errors (Loudness) dB(A)
Num: 9
Avg:-72.5 dB(A)
Max: -23.7
Error Muting Samples
Num: 0
Avg: 0.0 Samples
Max: 0
Skips Samples
Num: 1
Avg: 408.0 Samples
Max: 408
Total Test Result
81.5 points (of 100.0 maximum)

- Conclusion

Test Disc
Reading Speed
Score
EAC CD-R
4X
70.5
Max
69.8
ABEX TCD-721R
4X
Not completed!
Max
68.1
ABEX TCD-726
4X
80.9
Max
81.5
Average Score
74.16

The PleXWriter PX-W4824A gets an average 74.16 score out of 100 at our reading error correction tests.

- C2 Information accuracy

- Introduction

The Advanced DAE Error Correction tests are available in the latest version of Nero CD Speed. With the A-BEX TCD-721R disc, we can test the drive's C2 error information accuracy. First we created the image with the A-BEX TCD-714 test disc. Then we tested with the Advanced DAE Error Correction test, the C2 error information accuracy. According to the CD Speed author, the C2 accuracy should be very high (99%) to be useful. The "Quality" test score table is shown below:

  • 0-50: bad
  • 51-60: not so good
  • 61-70: ok
  • 71-80: good
  • 81-90: very good
  • 91-100: excellent!

- Test Results (MAX Speed)

The PX-W4824A drive got an 83.12% score (out of 100% max) for the C2 accuracy and 66.6 score for the overall reading error correction capabilities with the A-BEX TCD-721R test disc. The 83% score is actually very bad because means that the PX-W4824A misses almost 1 out of 5 errors! In other words you will not get good results with software which depends on C2 error information, like CD-R media quality scanners or DAE ripping software like EAC.




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