It is true that audio CDs use all 2352 bytes per block for sound samples, while CD-ROMs use only 2048 bytes per block, with most of the rest going to ECC (Error Correcting Code) data. The error correction that keeps your CDs sounding the way they're supposed to, even when scratched or dirty, is applied at a lower level. So while there isn't as much protection on an audio CD as there is on a CD-ROM, there's still enough to provide perfect or near-perfect sound quality under adverse conditions.

All of the data written to a CD uses CIRC (Cross-Interleaved Reed-Solomon Code) encoding. Every CD has two layers of error correction, called C1 and C2. C1 corrects bit errors at the lowest level, C2 applies to bytes in a frame (24 bytes per frame, 98 frames per sector). In addition, the data is interleaved and spread over a large arc. (This is why you should always clean CDs from the center out, not in a circular motion. A circular scratch causes multiple errors within a frame, while a radial scratch distributes the errors across multiple frames.)

If there are too many errors, the CD player will interpolate samples to get a reasonable value. This way you don't get nasty clicks and pops in your music, even if the CD is dirty and the errors are uncorrectable. Interpolating adjacent data bytes on a CD-ROM wouldn't work very well, so the data is returned without the interpolation. The second level of ECC and EDC (Error Detection Codes) works to make sure your CD-ROM stays readable with even more errors.

It should be noted that not all CD players are created equal. There are different strategies for decoding CIRC, some better than others.

Andy McFadden

The lowest level is "EFM" or eight-to-fourteen modulation". It takes each byte, and turns it into 14 bits in a fashion wherein it is possible to both correct many misreads as well as tell when a misread is uncorrectable.

Then there is an interleaving, to allow for scratches, holes, pits, etc in the CD data layer.

After that a reed-solomon code is used to error correct and error check again.

After that, if the RSC can't get it right, the player either interpolates (for a block or two) or mutes.

On most CDs there is almost nothing getting past the reed-solomon code. Usually in fact nothing at all

Source: http://www.hydrogenaudio.org/

The funny thing is, that the low cost CD723 player is able to read any CD or CD-R that is not severely scratched without any interpolation or hold. You can even put it upside down, there will be zero interpolation /hold.

Uncorrected samples could only be generated by dropping the player (5cm) or by extremely scratched CDs.

Source: http://www.jitter.de

...all CD Ripping programs, all brands of DVD and CD drive will rip bit perfect (drive offset accounted for, BTW the offset is not audible past the first micro-seconds of a track) on the majority (over 95%) of undamaged discs. The differences in CD ripping software: ability to detect errors, potentially correct errors (by re-reading) and eventually report errors if they cannot be corrected.

Spoon (developer dBpoweramp)

Usually if there are problems with a CD it's only in one track. dBpoweramp will also report how many problem frames are involved (75 frames per second). Often there is just one frame that's bad. If you go and listen to the track then there is a 50-50 chance you won't hear anything wrong. If you own a CD and it rips with errors and you want to listen to it, then just do so. You may be pleasantly surprised that the error are inaudible.

If you get errors on more than a small fraction of your disks and the disks have no obvious problems then it is likely that your drive isn't working so well. The best thing to do then is to try reading the problem disk on a different drive, e.g. on a different computer.

I haven't seen a pattern on whether EAC or dBpoweramp does better on the marginal disks. I have seen a pattern when using different drives.

Tony Lauck