Adaptive Frequency Prediction

A method of receiving an encoded audio signal, the method comprising:

• receiving the encoded audio signal, the encoded audio signal having an available low band comprising a plurality of spectrum coefficients;
• predicting an extended spectral fine structure of a high band from the available low band, wherein the spectral fine structure of the high band comprises at least one subband having a plurality of spectrum coefficients, wherein predicting comprises
• preparing the plurality of spectrum coefficients of the available low band,
• defining prediction parameters and variation ranges of the prediction parameters based on the available low band,
• estimating possible best prediction parameters based on a regularity of a harmonic structure of the available low band,
• producing the extended spectral fine structure of the high band based on the estimated possible best prediction parameters of the at least one subband.

A system for transmitting an audio signal, the system comprising:

• a transmitter comprising an audio coder, the audio coder configured to:
• convert the audio signal to low band spectral information comprising a plurality of spectrum coefficients,
• predict a high band extended spectral fine structure from the low band spectral information for at least one subband, the high band extended spectral fine structure comprising a plurality of spectrum coefficients,
• prepare the spectrum coefficients of the low band spectral information,
• define prediction parameters for the high band extended spectral fine structure and index ranges of the prediction parameters,
• determine possible best indices of the prediction parameters, wherein a prediction error is minimized between a reference subband in high band and a predicted subband that is selected and composed from an available low band, and
• produce an encoded audio signal comprising the possible best indices of the prediction parameters;
• wherein, the transmitter is configured to transmit the encoded audio signal.