Patent ID: 7343292

Claim:
An audio signal encoder comprising: a mapping transform unit for subjecting input audio signals to a mapping transform and generating frequency region signals that take frequency as a variable; a code amount designation unit for supplying as a code amount a coding bit rate that has been set or is designated by a user; a frequency region signal compression encoder for performing a compression encoding processing on said frequency region signals based on the code amount designated by the code amount designation unit and generating a bitstream; and a bandwidth-limiting unit for: executing bandwidth-limiting processing in accordance with attenuation characteristics that have been set corresponding to the code amount designated by said code amount designation unit, said bandwidth-limiting processing including steps of allocating a part of the frequency zone covered by said frequency region signals to an attenuation frequency zone, and multiplying the values of frequency region signals in said attenuation frequency zone by attenuation coefficients each having a value of 1 or less to attenuate said frequency region signals in said attenuation frequency zone; and supplying frequency region signals that have undergone said bandwidth-limiting processing to said frequency region signal compression encoder.