Sync restoring method for variable-length decoding and apparatus thereof

Claim 1

A sync restoring apparatus for receiving variable-length-coded data on the basis of a data format including a block end signal representing a first block having a predetermined magnitude and a second block larger than the first block, and variable-length-decoding the received data, said sync restoring apparatus comprising: a first-in-first-out (FIFO) memory for storing the received variable-length-coded data and sequentially outputting a predetermined number of bits of data from firstly stored data every time a read signal is applied to the FIFO memory; a variable-length-decoder for performing a variable-length-decoding operation on data output from said FIFO memory, outputting the block end signal obtained by the variable-length-decoding operation, and generating a data request signal every time a number of bits of data used in the variable-length-decoding operation becomes a predetermined number; an error detector for judging whether the block end signal output from the variable-length-decoder is decoded at an exact variable-length-decoding time based on a data format, and generating an error signal when a number of the block end signals which are not decoded at the exact variable-length-decoding time obtained by the judged result is equal to or larger than a predetermined limit value; an interfacer coupled to transmit the data output from the FIFO memory to the variable-length-decoder according to the read signal, and if the error signal is not generated in the error detector, applying a read signal to the FIFO memory according to the data request signal generated from the variable-length-decoder, while if the error signal is generated in the error detector, applying read signals to the FIFO memory until error-detected second block data is wholly read from the FIFO memory, independently of the data request signal; and a controller for controlling the variable-length-decoder so as to stop the decoding operation of the variable-length-decoder when the error signal output from the error detector is applied to the controller, while when the second block data following the error-detected second block is supplied to the variable-length-decoder, the decoding operation is performed.