dburtsev (dburtsev) wrote,


There is more than one way to handle C1 and C2 error detection/correction, but a simple and common way is to detect and correct up to two errors per frame in each stage and detect three or more errors:

  • E11: 1 error detected and corrected by C1 layer
  • E21: 2 errors detected and corrected by C1 layer
  • E31: 3 or more errors detected but not corrected by C1 layer

The sum of these (per second) is called the Block Error Rate: BLER=E11+E21+E31

  • E32: 3 or more errors detected but not corrected by C2 layer

Any E31 is un-correctable by the C1 layer and will result in the bytes in that frame being redistributed into multiple frames which are passed to the C2 layer.

Any E32 is un-correctable by the C2 layer and will result in interpolation being used for Audio CDs or will result in third layer error correction being used for Data CDs.

Different drives have different ways of reporting these errors in a Disc Quality scan.  Lite-On CD-RW drives will report C1 and C2 errors this way:

  • C1=BLER=E11+E21+E31
  • C2=E32

Here is an easier way to look at Disc Quality Scanning:

A written CD-R disc will always have some C1 errors; C1 errors are easily corrected by the drive’s error correction capabilities. The next level of errors is C2, while C2 errors could also be corrected by most drive’s error correction capabilities; they are not wanted on a good quality disc. A good disc should not contain any C2 errors, and preferably have an average C1 error amount of below 2.0 for the best discs, or at least below 10.0 averages for good quality discs. After C2 errors, there are only un-correctable errors that will make a disc unusable.

In short, our analysis will be based on this guideline to determine the quality of the burned disc:

CD-R/RW quality scans guideline

Average C1 errors

C2 errors


2 and lower



Between 2.1 and 5


Very good

Between 5.1 and 10



Between 10.1 and 50



Above 50



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