Transformations for signal enhancement coding

A method of decoding a signal, the method comprising:

• receiving an encoded frame and first and second sets of encoded residual data;
• passing the encoded frame to a decoding module, the decoding module being configured to generate a decoded frame by decoding the encoded frame;
• decoding the first and second sets of encoded residual data to generate first and second sets of reconstructed residual data, wherein the decoding comprises transforming the first and second sets of encoded residual data into reconstructed first and second sets of residual data respectively;
• combining the first set of reconstructed residual data with the decoded frame to obtain a combined frame;
• up-sampling the combined frame to obtain a reference decoded frame;
• and
• combining the second set of reconstructed residual data with the reference decoded frame to obtain a reconstructed frame.

A decoder configured to:

• receive an encoded frame and first and second sets of encoded residual data;
• pass the encoded frame to a decoding module, the decoding module being configured to generate a decoded frame by decoding the encoded frame;
• decode the first and second sets of encoded residual data to generate first and second sets of reconstructed residual data, wherein the decoding comprises transforming the first and second sets of encoded residual data into reconstructed first and second sets of residual data respectively;
• combine the first set of reconstructed residual data with the decoded frame to obtain a combined frame;
• up-sample the combined frame to obtain a reference decoded frame;
• and
• combine the second set of reconstructed residual data with the reference decoded frame to obtain a reconstructed frame.