METHOD OF CONVERTING A STREAM OF DATABITS OF A BINARY INFORMATION SIGNAL INTO A STREAM OF DATABITS OF A CONSTRAINED BINARY CHANNEL SIGNAL, DEVICE FOR ENCODING, SIGNAL COMPRISING A STREAM OF DATABITS OF A CONSTRAINED BINARY CHANNEL SIGNAL, RECORD CARRIER

摘要

A sequence of n-bit information words is converted into a sequence of corresponding channel words, some channel words having mi-bits and other channel words having m2-bits, and the sequence of channel words is transmitted. The information words are converted into corresponding mi-bit channel words in accordance with a channel code C1, and the information words are converted into corresponding m2-bit channel words in accordance with a channel code C2 that is different than the channel code C1. The sequence of channel words complies with a runlength constraint and with a second constraint related to the parity of the m2-bit channel words. Each channel code includes a predetermined plurality of alternative channel words for use in the conversion of each information word. For channel words immediately following a previous channel word in the sequence, the selection of the channel word from the predetermined plurality of channel words depends on an end part of the immediately preceding channel word so as to comply with the runlength constraint. The predetermined plurality of m2-bit channel words includes channel words having opposite polarity, and the selection of m2-bit channel words from the predetermined plurality of m2-bit channel words also depends on the second constraint related to the parity of the m2-bit channel words.