Apparatus and method for adaptive time/frequency-based encoding/decoding

An apparatus and a method for adaptive time/frequency-based encoding/decoding are provided to achieve high compression efficiency by encoding a frequency band suitable for audio compression in a time-based encoding type and encoding the other frequency band in a frequency-based encoding type. A conversion and mode determination unit(100) divides a frequency region into a plurality of frequency regions in an input audio signal, and determines a time-based encoding mode or a frequency-based encoding mode for the divided frequency regions. An encoding unit(110) encodes the signals of the divided frequency regions in the determined encoding mode. A bit stream output unit(120) outputs the encoded data, the divided information, and the determined encoding mode information.