1. Audio coding system comprising: a linear prediction (LP) unit ( 201 ) for filtering an audio signal based on a LP filter, the LP unit operating on a first frame length of the audio signal; an adaptive length transformation unit ( 202 ) for transforming a frame of the audio signal into a transform domain, the transformation being a Modified Discrete Cosine Transform (MDCT) operating on a variable second frame length; a quantization unit ( 203 ) for quantizing a MDCT-domain signal; a gain curve generation unit ( 1070 ) for generating MDCT-domain gain curves based on magnitude responses of the LP filter; and a mapping unit ( 1100 ) for mapping LP parameters to corresponding frames of the MDCT-domain signal.