The present document relates to audio coding systems. In particular, the present document relates to efficient methods and systems for parametric multi-channel audio coding. An audio encoding system (500) configured to generate a bitstream (564) indicative of a downmix signal and spatial metadata for generating a multi-channel upmix signal from the downmix signal is described. The system (500) comprises a downmix processing unit (510) configured to generate the downmix signal from a multi-channel input signal (561); wherein the downmix signal comprises m channels and wherein the multi-channel input signal (561) comprises n channels; n, m being integers with m<n. Furthermore, the system (500) comprises a parameter processing unit (520) configured to determine the spatial metadata from the multi-channel input signal (561). In addition, the system (500) comprises a configuration unit (540) configured to determine one or more control settings for the parameter processing unit (520) based on one or more external settings; wherein the one or more external settings comprise a target data-rate for the bitstream (564) and wherein the one or more control settings comprise a maximum data-rate for the spatial metadata.