Patent ID: 7761177

Claim:
A method for decoding an encoded audio signal performed by a decoding apparatus, comprising: receiving, in the audio decoding apparatus, a downmix signal, fixed channel configuration information indicating a predetermined tree configuration and arbitrary channel configuration information including a type identifier comprising an arbitrary tree configuration, wherein the type identifier includes previous signal division information and current signal division information corresponding to one of a division identifier and a non-division identifier, the division identifier indicating a presence of a channel division at a node of a layer and the non-division identifier indication an absence of a channel division at a node of a layer; generating, in the audio decoding apparatus, fixed output channels using the fixed channel configuration information and the downmix signal; and generating, in the audio decoding apparatus, at least one arbitrary output channel using the arbitrary channel configuration information and the fixed output channels such that each arbitrary channel is generated from only one fixed channel, which comprises: assigning a node to lower layer if the previous signal division information is represented by the division identifier; and assigning an arbitrary output channel if the previous signal division information is represented by the non-division identifier, wherein a number of the fixed output channels is more than a number of channels of the downmix signal, wherein a number of output channels of the decoded audio signal including the at least one arbitrary output channel is greater than the number of the fixed output channels, wherein, if the previous signal division information for a node of an upper layer is the division identifier, the current signal division information indicates whether a signal division at the node of the lower layer is present, wherein the previous signal division information is adjacent to the current signal division information in a bitstream.