Hmm...well, if we're going to start throwing around credentials (an exercise I'm not generally fond of), I guess I should point out that I am a mathematics professor at a major American university, and that while my main research area is not the theory of error correcting codes, I have on occasion taught courses in the subject. To engineers.
Upthread a comparison was drawn between the degradation of a stylus due to wear, in which distortion might gradually increase with time or plays, and the degradation of a CD player due to gradual laser misalignment. I believe they are not at all comparable. If a packet of data in a CD is missing enough bits that it does not decode, it can't be approximately decoded. The error-correction algorithm doesn't give values over the weeks or months that are less and less correct. A given player might use a strategy to replace missing packets, either by resampling or perhaps by interpolating the value between neighboring time readings, but if a laser is degrading over time to the point where you are getting a significant number of misreadings, then the player will simply fail.
In practice I've never owned a CD player that failed gradually in this way. Some of my players got worse by virtue of refusing to read some CDs, and shortly after that they generally refused to read all CDs. They didn't just gradually distort more and more. And if I had one that did that, I would certainly not suspect the digital side, pace restorer-john.
Upthread a comparison was drawn between the degradation of a stylus due to wear, in which distortion might gradually increase with time or plays, and the degradation of a CD player due to gradual laser misalignment. I believe they are not at all comparable. If a packet of data in a CD is missing enough bits that it does not decode, it can't be approximately decoded. The error-correction algorithm doesn't give values over the weeks or months that are less and less correct. A given player might use a strategy to replace missing packets, either by resampling or perhaps by interpolating the value between neighboring time readings, but if a laser is degrading over time to the point where you are getting a significant number of misreadings, then the player will simply fail.
In practice I've never owned a CD player that failed gradually in this way. Some of my players got worse by virtue of refusing to read some CDs, and shortly after that they generally refused to read all CDs. They didn't just gradually distort more and more. And if I had one that did that, I would certainly not suspect the digital side, pace restorer-john.
