Error correction
Error correction ability is a very important feature of every optical drive. For correct reading of the sector responsible are both: optical system and hardware correction mechanism of the drive. It happens quite often that after several tests in identical conditions we get different results. In that case we present an average result.
Nero CDSpeed - CD Quality
In Nero CDSpeed software there is a 'CD Quality' feature. We can use this function to determine the influence of read error amount on the audio extraction speed. Below screenshot you can see a graph that compares error counts of different drives. The less errors, the better drive.
Dictionary:
Błędy - Errors
Całość - Total
Maksimum - Maximum
Średnio - Average
CD DAE
CD DAE software is designed to rip audio data from CD. Each track is read twice. During the second pass, the program compares our two passes and every difference is treated as a read error. Below the screenshot you can see a graph. This graph is based on the error account reported by CD DAE. The less errors, the better drive.
Error Correction - data CDs
Once more we used Nero CD Speedwith its Scandisk/Surface function. As a result we get some kind of map of our medium - a graphical representation of the positions of the CD damages. Green fields represent correct sectors; yellow fields mean that the drive had to use the error correction mechanism to read that sector; and red fields show the damaged sectors that the drive was not able to correct.
The graphs below are based on data from read tests with different drives. The media used there were some special test discs. Each column consists of two colors/fields. The field on the left represent the percentage content of correct sectors, which are the sectors read without using the error correction mechanism. On the right is shown the amount of sectors read with the help of error correction. Just after the columns we can see numbers, representing the respective percentage.
Reading of a damaged pressed CD
The test CD has a lot of scratches - it looks frosted.
Dictionary:
Błędy - Errors
Nie testow. - Not tested
Nie używ. - Not used
Dobre - Good
Uszkodzone - Damaged
Nieczytelne - Unreadable
Test powierzchni - Surface scan
Read test - media recorded too fast
When we record on low quality media, or when we record media with a speed higher than the speed declared by the producer, we may produce bad sectors. Such errors may cause the medium to become unreadable. And nothing informs us that something is wrong during such a recording. Nero CD Speed, scandisk/surface feature can detect such bad sectors. You can see it below - similarly like before.
Dictionary:
Błędy - Errors
Nie testow. - Not tested
Nie używ. - Not used
Dobre - Good
Uszkodzone - Damaged
Nieczytelne - Unreadable
Test powierzchni - Surface scan
Error correction 
