a selected channel of a multi - channel signal which is represented by frames composed from sampling values having a high time resolution can be encoded with higher quality when a wave form parameter representation representing a wave form of an intermediate resolution representation of the selected channel is derived , the wave form parameter representation including a sequence of intermediate wave form parameters having a time resolution lower than the high time resolution of the sampling values and higher than a time resolution defined by a frame repetition rate . the wave form parameter representation with the intermediate resolution can be used to shape a reconstructed channel to retrieve a channel having a signal envelope close to that one of the selected original channel . the time scale on which the shaping is performed is shorter than the time scale of a framewise processing , thus enhancing the quality of the reconstructed channel . on the other hand , the shaping time scale is larger than the time scale of the sampling values , significantly reducing the amount of data needed by the wave form parameter representation .