My understanding is that if a CD is in good physical condition, the main reason why it might sound inferior to playback of a bit-perfect computer file is NOT errors that the player can't correct on the fly in a bit-perfect manner, which would therefore require inexact interpolation. My understanding, based on numerous references I have seen in the past, is that for a disk that is in good condition that will happen rarely during the playing of a disk, and not at all in many or most cases.
The main reason that real-time CD playback may provide inferior results is that electrical noise generated by the servo mechanisms and circuitry in the transport part of the player, as it tracks the disk, may couple into unrelated downstream circuitry in the player, causing jitter in the D/A conversion process, and/or effects on the analog signal path. The degree to which that occurs will be dependent on the design of the particular player, of course, as well as on the condition of the disk.
From this Wikipedia writeup:
Note that the term "error correction," as properly defined in this context, refers to bit-perfect correction. "Error interpolation" is the term used to refer to the less than bit-perfect approximation that can occur (rarely) when bit-perfect correction fails.
And from a post by Kirkus in this Audiogon thread:
-- Al
The main reason that real-time CD playback may provide inferior results is that electrical noise generated by the servo mechanisms and circuitry in the transport part of the player, as it tracks the disk, may couple into unrelated downstream circuitry in the player, causing jitter in the D/A conversion process, and/or effects on the analog signal path. The degree to which that occurs will be dependent on the design of the particular player, of course, as well as on the condition of the disk.
From this Wikipedia writeup:
Reed–Solomon coding is a key component of the compact disc.... In the CD, two layers of Reed–Solomon coding separated by a 28-way convolutional interleaver yields a scheme called Cross-Interleaved Reed Solomon Coding (CIRC).... The result is a CIRC that can completely correct error bursts up to 4000 bits, or about 2.5 mm on the disc surface. This code is so strong that most CD playback errors are almost certainly caused by tracking errors that cause the laser to jump track, not by uncorrectable error bursts.
Note that the term "error correction," as properly defined in this context, refers to bit-perfect correction. "Error interpolation" is the term used to refer to the less than bit-perfect approximation that can occur (rarely) when bit-perfect correction fails.
And from a post by Kirkus in this Audiogon thread:
CD players, transports, and DACs are a menagerie of true mixed-signal design problems, and there are a lot of different noise sources living in close proximity with suceptible circuit nodes. One oft-overlooked source is crosstalk from the disc servomechanism into other parts of the machine . . . analog circuitry, S/PDIF transmitters, PLL clock, etc., which can be dependent on the condition of the disc.... One would be suprised at some of the nasty things that sometimes come up out of the noise floor when the focus and tracking servos suddenly have to work really hard to read the disc.Regards,
-- Al