Apparatus and method for encoding/decoding signal

An apparatus for decoding a signal, comprising:

• a hardware bit unpacking unit receiving an arbitrary down-mix signal and spatial information, wherein the spatial information includes compensation information necessary for compensating for the arbitrary down-mix signal, arbitrary down-mix identification information indicating whether the compensation information is included in the spatial information, channel level difference information describing level differences between two channels of a multi-channel signal and inter channel correlation information describing an amount of correlation between two channels of the multi-channel signal;
• a hardware down-mix compensation unit compensating the arbitrary down-mix to ensure that a level of the arbitrary down-mix signal is same as a level of a down-mix signal obtained when the spatial information was estimated on an encoding apparatus signal using the compensation information;
• and
• a hardware three-dimensional (3D ) rendering unit generating a 3D down-mix signal by performing a 3D rendering operation on the compensated arbitrary down-mix signal wherein the 3D rendering operation is performed using a head related transfer function (HRTF), and
• wherein the 3D down-mix signal is a stereo down-mix signal with 3D effect,
• wherein the compensation information comprises information regarding a difference between the down-mix signal generated by the encoding apparatus and the arbitrary down-mix signal generated by another encoding apparatus.