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 the error correction capabilities of the firmware) can be estimated by checking the time positions the errors start, during reading. Higher wedges mean lower error correction capabilities.

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 is not affected much in high and very low frequencies, but mainly in 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 a 6 dB(A) volume. (6 dB(A) louder means that the sound is two times louder)
• " For the test CD, a wedge 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. For example, 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 between a -6 dB of music, you will probably not hear a -72 dB (A) or even -66 dB (A)...

- Explanation

After the analyze.exe software finishes, we get a detailed report about 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 gives information 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 start 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 defected area of the disc seems to be very hard for Sony CRX-210E1 to read. The spikes in this area are high, producing many errors. The scratched areas after the 48 min of the disc gave less errors, as you can see from the graph. The average signal/noise level is -81.7dB(A), which is low enough. The total score for the drive is 68.1. In the same test, the PlexWriter PX-4824A got 70.5.

- Test Results (Max Reading)

In the maximum ripping speed, the results were unexpectedly improved over the previous we got in the 4X ripping speed. The amount of the Loudness errors is small and the average signal level is -86dB(A). In addition, no Muting and skip samples are reported, resulting to a very high score of 88.9 points. We are very skeptical for the accuracy of the results, but the phenomenon to get best results maximum ripping speed appeared in previous tests, as well. EAC author is aware of this and we hope that we will have a good explanation soon.

- 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.

- Test Results (4X speed)

The amount of the Loudness errors is not higher than we expected to be with this test disc. The score is not high, and the increased length of the error muting samples among with the skip samples, lead to 63.4 points total score.

- Test Results (Max speed)

In the maximum ripping speed the results are better. There are less errors loudness, and no skip samples. The error muting samples are also less, and the total score is 75.8 points.

- 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)

The signal /noise rate is very low but the skip samples were large, leading to only 58 points total score.

- Test Results (Max Speed)

The average Loudness errors is only -78.4dB(A). The total score for this test is 78.3 points.

- Conclusion

Compared to the total score of PlexWriter PX-W4824A, the Sony drive was not so accurate and could be improved.

- 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!

A newer version of EAC's analyse software also offers C2 accuracy %. Both results are posted below.

- Test Results (MAX Speed)

The C2 accuracy of the Sony CRX-210E1 is very high, and reaches the 99.96% of the total errors. Nero CDSpeed gave the drive a 79.9 total quality score (good).

The EAC results are the same, at least for the maximum speed, where the Sony drive gets a 100% score. Again the results are not so good for the 4X reading speed.