Low-frequency emphasis for lpc-based coding in frequency domain

Method for encoding a non-speech audio signal so as to produce therefrom a bitstream, the method comprising:

• filtering with a linear predictive coding filter comprising a plurality of linear predictive coding coefficients and converting a frame of the audio signal into a frequency domain in order to output a spectrum based on the frame and on the linear predictive coding coefficients;
• calculating a processed spectrum based on the spectrum, wherein spectral lines of the processed spectrum representing a lower frequency than a reference spectral line are emphasized;
• and
• controlling the calculation of the processed spectrum depending on the linear predictive coding coefficients of the linear predictive coding filter;
• producing a quantized spectrum based on the processed spectrum;
• and
• embedding the quantized spectrum and the linear predictive coding coefficients into the bitstream.

Method for decoding a bitstream based on a non-speech audio signal so as to produce from the bitstream a non-speech audio output signal, in particular for decoding a bitstream produced by the method according to the preceding claim, the bitstream comprising quantized spectrums and a plurality of linear predictive coding coefficients, the method comprising:

• extracting the quantized spectrum and the linear predictive coding coefficients from the bitstream;
• producing a de-quantized spectrum based on the quantized spectrum;
• calculating a reverse processed spectrum based on the de-quantized spectrum, wherein spectral lines of the reverse processed spectrum representing a lower frequency than a reference spectral line are deemphasized;
• and
• controlling the calculation of the reverse processed spectrum depending on the linear predictive coding coefficients comprised in the bitstream.