chsbiking said “I think they should be forced to put a label on it. The reason is, is because the copy protection messes around with the error correction codes on the CD. Which means the CD won’t last as long as a normal CD.” But this is false information. The following text describes what role error correcting codes play on compact discs: “The storage medium used is a compact disc (CD), a flat circular disc resembling a conventional phonograph record but less that 5 inches in diameter, aluminized (for reflectivity, as we shall see is necessary) and coated with a clear protective plastic. Rather than representing an audio signal as a continuous waveform, for digital recordings the signal is sampled at a fixed time intervals, quantized and stored as a sequence of binary numbers. The method of coding sound for storage and playback is called (linear) pulse code modulation (PCM). At a given instance in the time the sound wave is sampled, and the amplitude is determined and assigned a discrete value from 1 to (2^16)-1. This value is given as a binary 16-tuple. Actually two samples, one for the left channel and one for the right, are taken. These samples are taken at a rate of 44,100 per second (44.1 kHz). Each binary 16-tuple is taken to represent two field elements from GF(2^8), and hence each sample produces 4 GF(2^8) symbols. On playback, the compact disc player will have to process (44,100)(32)=1,411,200 bits of audio data per second. As will be seen shortly, for various reasons the number of bits actually processed per second is substantially higher than this. For purposes of error correction, information is grouped into segments called ‘frames’, with each frame holding 24 data symbols. The code used for error correction is a Cross-Interleaved-Reed-Solomon Code (CIRC), obtained by cross-interleaving two Reed-Solomon codes. The 24 symbols from GF(2^8) from 6 samples are used as information symbols in a (28,24)-RS code C1 over GF(2^8). The code is now interleaved to a depth of 28 using a 4-frame delay interleave. The resulting columns of 28 symbols are used as information symbols in a (32,28)-RS code C2 over GF(2^8), with 4 additional parity check symbols determined by each column. (We note that these codes are actually shortened Reed-Solomon codes. Shortened codes are defined in a later exercise). The symbols in a frame, which now corresponds to a C2 codeword, are then regrouped to separate the odd and even-numbered symbols of that frame into distinct frames, with the symbols in odd-numbered symbol positions of one frame grouped with symbols in even-numbered positions from the next frame in time to form a new frame. At this stage the frame consists of 32 8-bit symbols (24 audio data symbols and 8 parity symbols). One more 8-bit symbol is addede which holds ‘control and display’ information, including information for the disc directory and unused bits (possibly for future use). In order to complete the bit description of a frame we require some knowledge of how the information is stored and read from the disc itself.” After that it gets a little technical, but a nice theorem tells us that “An (n,k)-RS code over GF(2^m) implies the existence of a binary (nm,km)-code with burst error correcting capability m(floor((n-k)/2)-1)+1.” The significance of the above observation is that Reed-Solomon codes have a high burst error correction rate. A burst error that occurs over the binary channel will affect a number of sequential bits. If the RS-code chosen can correct this burst error, then, in a nutshell, you’ll have your audio played back without any problems. So, copy protection of compact discs and the error correcting codes that are used to ensure proper audio playback (from things like scratches, dirt or other minor problems) have nothing to do with each other. The text excerpts I quoted above are both from “An Introduction to Error Correcting Codes with Applications” by Vanstone and Oorschot. Thus your CDs will last just as long… probably DUE to the error correcting codes used, rather than the other way around.