An audio signal is encoded by a first waveform encoder (103) to generate a first waveform based bit-stream component. A second encoder (105) encodes the audio signal to generate a second bit-stream component comprising first enhancement data and a third encoder (107) encodes the audio signal to generate a third bit-stream component comprising second enhancement data for the first waveform based bit-stream component. The first and second bit-stream components correspond to a first representation of the audio signal and the first and third bit-stream components correspond to a second representation of the audio signal. A scalable audio bit-stream is generated by a bit-stream generator (109). The different representations may be selected between by a decoder thereby allowing a flexible and scalable bit-stream to be communicated. The second encoder (105) may specifically be a waveform encoder and the third encoder (107) may specifically be a parametric encoder.