Audio encoding apparatus and method, and audio decoding apparatus and method

Disclosed are an audio encoding apparatus for encoding audio signals and an audio decoding apparatus for decoding the encoded audio signals through a lossless encoding method or a lossy encoding method. The audio encoding apparatus according to one embodiment may comprise: an input signal type determining unit for determining the type of an input signal based on the characteristics of the input signal; a residual signal generating unit for generating a residual signal based on the output signal from the input signal type determining unit; and an encoding unit for performing lossless encoding or lossy encoding using the residual signal.