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I don't get it. It's not analog data. So how can quality of digital data differ unless you have deteriorated disk and simply data loss? Is this about what hardw

by shmerl 4y ago

I don't get it. It's not analog data. So how can quality of digital data differ unless you have deteriorated disk and simply data loss? Is this about what hardware recovers data from defective disks better?

userbinator 4y ago
The data is digital but the reading is actually somewhat error-prone; even when the disc and drive are perfect, occasional correctable errors will appear. Also, in audio mode, the error correction is weaker than in data mode.
- shmerl 4y ago
  So it means some percentage of data can end up being incorrect depending on the quality of the drive?
  - giantrobot 4y ago
    Sort of. If you take the same disc between different drives it's possible to get different readings on each of the drives. Red Book audio data is at a fairly high frequency with multiple channels. A few corrupted samples are likely not noticeable. So its error correction is best effort and interpolates between previous and later samples. Two different drives with different read mechanisms and implementation of the Red Book standard might produce different samples when reading an error and depending on the nature of the error.
  - mlyle 4y ago
    If your disc is marginal, some data can end up being incorrect. Depending upon the quality of the drive mechanism itself, and how it reports errors to the ripping software, you can end up with incorrect data more or less often.
adql 4y ago
There is no "digital data" in physical reality. There is "analog data that is within a threshold of the bit that we decided". Hard drive or CD doesn't read "1" or "0", it reads say (after normalization) 0.823V. Or 0.654V. Or 0.983V. The way circuit is designed decides that above some value its "1", below that is "0", but physical deterioration and material variance will change that value and it will differ bit by bit too. It's all good when signal is strong and say all the 1's are > 0.8, all the 0's are < 0.2 but when it starts to blur (again, bad media, degradation etc.) you get bits that can be 1 one read, 0 another. And having "tri state" input that can say "ok, it's between 0.4-0.6, we can't tell whetehr that's 0 or 1" is generally rare.

by shmerl 4y ago

userbinator 4y ago

The data is digital but the reading is actually somewhat error-prone; even when the disc and drive are perfect, occasional correctable errors will appear. Also, in audio mode, the error correction is weaker than in data mode.

shmerl 4y ago
So it means some percentage of data can end up being incorrect depending on the quality of the drive?
- giantrobot 4y ago
  Sort of. If you take the same disc between different drives it's possible to get different readings on each of the drives. Red Book audio data is at a fairly high frequency with multiple channels. A few corrupted samples are likely not noticeable. So its error correction is best effort and interpolates between previous and later samples. Two different drives with different read mechanisms and implementation of the Red Book standard might produce different samples when reading an error and depending on the nature of the error.
- mlyle 4y ago
  If your disc is marginal, some data can end up being incorrect. Depending upon the quality of the drive mechanism itself, and how it reports errors to the ripping software, you can end up with incorrect data more or less often.

adql 4y ago

There is no "digital data" in physical reality. There is "analog data that is within a threshold of the bit that we decided". Hard drive or CD doesn't read "1" or "0", it reads say (after normalization) 0.823V. Or 0.654V. Or 0.983V. The way circuit is designed decides that above some value its "1", below that is "0", but physical deterioration and material variance will change that value and it will differ bit by bit too. It's all good when signal is strong and say all the 1's are > 0.8, all the 0's are < 0.2 but when it starts to blur (again, bad media, degradation etc.) you get bits that can be 1 one read, 0 another. And having "tri state" input that can say "ok, it's between 0.4-0.6, we can't tell whetehr that's 0 or 1" is generally rare.