Weight function determination device and method for quantizing linear prediction coding coefficient

1. A method of encoding a linear predictive coding (LPC) coefficient in an encoding device, the method comprising:

obtaining, performed by at least one processor, a line spectral frequency (LSF) coefficient from the linear predictive coding (LPC) coefficient of a subframe in an audio signal;

obtaining a magnitude weighting function of the subframe based on spectral magnitude of the LSF coefficient;

obtaining a frequency weighting function of the subframe based on frequency information of the LSF coefficient;

combining the magnitude weighting function and the frequency weighting function to obtain a first weighting function of the subframe;

obtaining a second weighting function of the subframe based on position information of adjacent LSF coefficients;

combining the first weighting function and the second weighting function to determine a third weighting function of the subframe; and

encoding the LSF coefficient based on the third weighting function,

wherein the magnitude weighting function is obtained based on a maximum value of a magnitude of a spectral bin corresponding to a frequency of the LSF coefficient and a magnitude of at least one spectral bin neighboring the spectral bin.

2. The method of claim 1 further comprising normalizing the LSF coefficient.

3. The method of claim 1 , wherein the magnitude weighting function is relevant to a spectral envelope of the audio signal.

4. The method of claim 1 , wherein the magnitude weighting function is determined by using magnitudes of one or more spectral bins corresponding to the frequency of the LSF coefficient.

5. The method of claim 1 , wherein the frequency weighting function is determined by using at least one selected from a perceptual characteristic and a formant distribution of the audio signal.

6. The method of claim 1 , wherein the first weighting function is determined based on at least one selected from a bandwidth, a coding mode, and an internal sampling frequency.

7. The method of claim 1 , wherein the second weighting function is determined by using the position information of adjacent LSF coefficients.

8. An apparatus of quantizing a line spectral frequency (LSF) coefficient in an encoding device, the apparatus comprising:

at least one processor configured to:

obtain an LSF coefficient from a linear predictive coding (LPC) coefficient of a subframe in an audio signal;

obtain a magnitude weighting function of the subframe based on spectral magnitude of the LSF coefficient;

obtain a frequency weighting function of the subframe based on frequency information of the LSF coefficient;

combine the magnitude weighting function and the frequency weighting function to obtain a first weighting function of the subframe;

obtain a second weighting function of the subframe based on position information of adjacent LSF coefficients;

combine the first weighting function and the second weighting function to determine a third weighting function of the subframe; and

encode the LSF coefficient based on the third weighting function,

wherein the magnitude weighting function is obtained based on a maximum value of a magnitude of a spectral bin corresponding to a frequency of the LSF coefficient and a magnitude of at least one spectral bin neighboring the spectral bin.

9. The apparatus of claim 8 , wherein the at least one processor is configured to determine the third weighting function to be identically applied to a frame-end subframe and a mid-subframe.

10. The apparatus of claim 8 , wherein the at least one processor is configured to apply the third weighting function during directly quantizing the LSF coefficient in a frame-end subframe.

11. The apparatus of claim 8 , wherein at least one processor is configured to weight an unquantized LSF coefficient of a mid-subframe by using the third weighting function; and quantize a weighting parameter for obtaining a weighted average between quantized LSF coefficients of frame-end subframes of a previous frame and a current frame based on the weighted LSF coefficient of the mid-subframe.

12. The apparatus of claim 11 , wherein the weighting parameter of the midsubframe is searched for in a codebook.

13. A non-transitory computer-readable storage medium storing a program for executing the method of claim 1 .