A scalable encoder (400, 500) for encoding a media signal, which media signal comprises an audio and/or speech signal, the scalable encoder (400, 500) comprising - first encoding means for producing a first data stream, which is a core data stream relating to the media signal, having a first bit-rate, - second encoding means for producing a second data stream, which comprises a set of enhancement data streams relating to the media signal, having a second bit-rate, and - a multiplexer for combining at least the first data stream and the second data stream into a third data stream and for storing the third data stream into a multiplexer buffer, characterized in that the scalable encoder (400, 500) further comprises - input means for transforming preference information that indicates a preferred ratio of the first and second bit-rates into first control information, and - control means (420, 421, 422) comprising first control means for determining a first target bit-rate for the first data stream in the third data stream, using first control information, and for adjusting the first encoding means to operate according to the first target bit-rate, and second control means for determining a second target bit-rate for the second data stream in the third data stream, using first control information, and for adjusting the second encoding means to operate according to the second target bit-rate, wherein the first and second control means (421, 422) are arranged to jointly adjust, in response to second control information indicating occupancy level of the multiplexer buffer to be less than a first threshold (T 2), said first and second target bit-rates in accordance with the preferred ratio of first and second bit-rates indicated in said preference information, and reduce, in response to the second control information indicating occupancy level of the multiplexer buffer to be greater than or equal to the first threshold (T 2), said first and second target bit-rates to respective minima. - first encoding means for producing a first data stream, which is a core data stream relating to the media signal, having a first bit-rate, - second encoding means for producing a second data stream, which comprises a set of enhancement data streams relating to the media signal, having a second bit-rate, and - a multiplexer for combining at least the first data stream and the second data stream into a third data stream and for storing the third data stream into a multiplexer buffer, characterized in that the scalable encoder (400, 500) further comprises - input means for transforming preference information that indicates a preferred ratio of the first and second bit-rates into first control information, and - control means (420, 421, 422) comprising first control means for determining a first target bit-rate for the first data stream in the third data stream, using first control information, and for adjusting the first encoding means to operate according to the first target bit-rate, and second control means for determining a second target bit-rate for the second data stream in the third data stream, using first control information, and for adjusting the second encoding means to operate according to the second target bit-rate, wherein the first and second control means (421, 422) are arranged to jointly adjust, in response to second control information indicating occupancy level of the multiplexer buffer to be less than a first threshold (T 2), said first and second target bit-rates in accordance with the preferred ratio of first and second bit-rates indicated in said preference information, and reduce, in response to the second control information indicating occupancy level of the multiplexer buffer to be greater than or equal to the first threshold (T 2), said first and second target bit-rates to respective minima. first control means for determining a first target bit-rate for the first data stream in the third data stream, using first control information, and for adjusting the first encoding means to operate according to the first target bit-rate, and second control means for determining a second target bit-rate for the second data stream in the third data stream, using first control information, and for adjusting the second encoding means to operate according to the second target bit-rate, wherein the first and second control means (421, 422) are arranged to jointly adjust, in response to second control information indicating occupancy level of the multiplexer buffer to be less than a first threshold (T 2), said first and second target bit-rates in accordance with the preferred ratio of first and second bit-rates indicated in said preference information, and reduce, in response to the second control information indicating occupancy level of the multiplexer buffer to be greater than or equal to the first threshold (T 2), said first and second target bit-rates to respective minima.