For this test, each CD-R disc was burned to its maximum capacity and at its maximum speed. Then the same disc is read with the CDSpeed software, and the disc was scanned for digital errors (BLER, C1 and C2) with our system provided by Clover Systems. To simplify the presentation, we present the BLER, E31 and E32 error rates for each disc, which unveil the most serious errors on each disc.

Disc Info

We weren't able to retrieve information about the inserted media with CDSpeed,

so we checked the disc using another drive and got the following:

The BenQ CD-R disc was burned at a speed of 28x using the CAV writing strategy.

Writing strategy - 37.33X Average
Writing time - 2:38 min

Reading strategy - 37.10X Average

The disc was read flawlessly. However, the integrity of the digital data is inspected in the following writing quality tests.

Writing Quality - Clover Systems

We present the BLER and the E31, E32 error rate flags, which practically determine whether the data can be retrieved with overall low error rates that can be digitally corrected. The E32 errors are uncorrectable and thus, they should not be present$ with a good burn. The E31 error rate is reported by the first error correction level (two available in total), and indicates the most severe case of errors from the first stage (three or more bad symbols -this block is uncorrectable at the the first stage and it is passed onto the C2 stage).

We see Low E31 and no E32 (uncorrectable) errors.

- About Clover Systems

The Clover Systems CDX Compact Disc Analyzer is a tool to quantitatively measure the quality of a CD. It will analyze CD-DA, CD-ROM, CD-ROM XA, CD-I, CD-R, Photo-CD, Enhanced CD and CD-RW discs at 4X, 8X, 24X, 32X or 40X speed. It effectively measures disc quality by examining the quantity and severity of CIRC errors generated during playback. It also provides the capability to measure signal parameters related to pit geometry, such as asymmetry and reflectivity. Together, all these bits of information provide a thorough analysis of disc quality. The Clover Systems Analyzers can also perform various format-checking tests on data discs, and do bit-for-bit data comparison on all types of CDs. All tests are carried out at the speed of 4X.

CIRC error correction uses two principles to detect and correct errors. The first is redundancy (extra information is added, which gives an extra chance to read the disc), and the second is interleaving (data is distributed over a relatively large physical area). The CIRC error correction used in CD players uses two stages of error correction, the well known C1 and C2, with de-interleaving of the data between the stages.

The error type E11 means one bad symbol was corrected in the C1 stage. E21means two bad symbols were corrected in the C1 stage. E31 means that there were three or more bad symbols at the C1 stage. This block is uncorrectable at the C1 stage, and is passed to the C2 stage. Respectively, E12 means one bad symbol was corrected in the C2 stage and E22 means two bad symbols were corrected in the C2 stage. E32 means that there were three or more bad symbols in one block at the C2 stage, and therefore this error is not correctable.

BLER (Block Error Rate) is defined as the number of data blocks per second that contain detectable errors, at the input of the C1 decoder. Since this is the most general measurement of the quality of a disc, you will find BLER graphs for all media tested . The Red Book specification (IEC 908) calls for a maximum BLER of 220 per second averaged over ten seconds. Discs with higher BLER are likely to produce uncorrectable errors. Al low BLER shows that the system as a whole is performing well, and the pit geometry is good. However, BLER only tells us how many errors were generated per second, and it does not tell us anything about the severity of those errors.