Patent ID: 7765104

Claim:
A method of decoding an audio signal performed by an audio coding system, the audio signal including a downmix signal and spatial information, the spatial information including a residual signal, comprising: extracting time slot information in variable bit length and residual band information in fixed bit length, the time slot information indicating a time slot to which a parameter set is applied and the residual band information indicating a number of parameter bands to which the residual signal is applied; updating a parameter of the parameter set by using the residual signal based on the residual band information, the parameter set including inter-channel correlation information; and decoding the audio signal by using the parameter set including the updated parameter based on the time slot information, wherein the process of extracting time slot information further comprises: extracting a number of time slots and a number of parameter sets from the audio signal to identify time slot information; determining a bit length of the time slot information, the bit length being variable according to the number of time slots, the number of parameter sets and previous time slot information associated with a previous parameter set; and extracting the time slot information based on the bit length, wherein a number of the time slot information is equal to the number of parameter sets.