Patent ID: 8867753

Claim:
An apparatus for upmixing a downmix audio signal describing one or more downmix audio channels into an upmixed audio signal describing a plurality of upmixed audio channels, the apparatus comprising: an upmixer configured to apply temporally variable upmix parameters to upmix the downmix audio signal in order to acquire the upmixed audio signal; and a parameter interpolator, wherein the parameter interpolator is configured to acquire one or more temporally interpolated upmix parameters to be used by the upmixer on the basis of an information describing a first complex-valued upmix parameter and a subsequent second complex-valued upmix parameter, wherein the parameter interpolator is configured to separately interpolate (a) between a magnitude value of the first complex-valued upmix parameter and a magnitude value of the second complex-valued upmix parameter, and (b) between a phase value of the first complex-valued upmix parameter and a phase value of the second complex-valued upmix parameter, to acquire the one or more temporally interpolated complex-valued upmix parameters.