Data conversion method and apparatus for converting undefined length data to fixed length data

Claim 1

A data conversion apparatus for converting undefined-length codes into fixed-length data, wherein all codes of the undefined-length codes having a code length greater than or equal to n+1 bits have all of the bits thereof except n bits from the least significant bit (LSB) the same, comprising: first input means for directly inputting the undefined-length code in which the code length is less than or equal to n bits, and for inputting only n bits from the LSB of the undefined-length code in which the code length is more than or equal to n+1 bits; second input means for inputting code length data representing the code length of the undefined-length code inputted from said first input means, and for shifting and outputting a bit position of the output undefined-length code; first hold means for holding residual data which could not be converted into fixed-length data by a previous conversion; second hold means for holding residual length data of the residual data held by said first hold means; conversion means for converting the undefined-length code into fixed-length data by packing the undefined-length code outputted from said shift-output means and the residual data held at said first hold means; and control means for controlling a shift-number of the bit position shifted by said shift-output means in accordance with the code length data inputted from said second input means and the residual length data held at said second hold means.