Patent ID: 8638945

Claim:
A method of decoding an audio signal, comprising: receiving, by a decoding apparatus, a bitstream including a three-dimensional (3D) down-mix signal, residual information and spatial information for expanding a down-mix signal to multi-channel signal, wherein the spatial information includes down-mix identification information indicating that the down-mix signal is 3D encoded and size information indicating a size in bits of residual information; skipping, by the decoding apparatus, the residual information in the bitstream based on the size information in the spatial information; determining, by the decoding apparatus, based on the down-mix identification information, whether the down-mix signal is a signal obtained by performing a 3D rendering operation; removing, by the decoding apparatus, 3D effect from the 3D down-mix signal by performing an inverse 3D rendering operation on the 3D down-mix signal, the inverse 3D rendering operation being performed using an inverse filter of a filter used for generating the 3D down-mix signal; and generating, by the decoding apparatus, a multi-channel signal using a down-mix signal obtained by the removal and the spatial information, wherein the 3D down-mix signal is a stereo down-mix signal with 3D effect which is reproduced as imaginary multi-channel signal, wherein the generating the 3D down-mix signal is performed using a head related transfer function (HRTF) and the spatial information.