tion, called by some the "big bang" in digital audio, came in the late 1970s with the audio CD (compact disk), as originated from a joint standardization effort of Sony and Philips. 6 The resulting audio-CD standard has been published in the Red Book. 7 As with speech, the A-D conversion is achieved with PCM, here with a two-channel (stereo effect), each made of 16-bit or two-byte codewords, at a sampling rate of 44.1 kHz. The first level of block code is called a frame. As illustrated in Fig. G1, the audio-CD frame includes six stereo samplings (2x2x6 = 24 bytes), an eight-byte error-correction field (CRC), a "subcode" byte for control and display purposes, e.g., telling to the CD player which 1 See, for instance: http://en.wikipedia.org/wiki/G.711. See, for instance: http://en.wikipedia.org/wiki/Pulse-code_modulation. See, for instance: http://en.wikipedia.org/wiki/A-law_algorithm 4 See, for instance: http://en.wikipedia.org/wiki/Mu-law_algorithm E. Desurvire, Wiley Survival Guides in Global Telecommunications, Signaling Principles, Network Proto- cols, and Wireless Systems (New York: J. Wiley & Sons, 2004). See, for instance: http://en.wikipedia.org/wiki/Compact_disk http://searchstorage.techtarget.com/ sDefinition/0,,sid5_gci503642,00.html; www.answers.com/topic/compact-disc-2. See, for instance: www.mpeg.org/MPEG/DVD/Red_Book/CD.html, Overview of data compression standards song or track is currently being read. This makes the frame 24 + 8 + 1 = 33 bytes long altogether, as seen from the figure. The frame is then processed according to the following. Each audio byte is first converted into a 14-bit EFM codeword (eight- to-fourteen modulation, also called 8/14 code). The EFM code expansion ensures that each 1 bit to be physically recorded on the CD is surrounded by at least two 0 bits (up to a maximum of ten 0 bits), which is a necessary condition for mechanical tracking, phase-locking, and synchronization purposes. The 14-bit EFM codeword then interleaved with a three-bit merging word, and finally appended wi