Audio signal processing method and device

1. An audio signal processing device for rendering an input audio signal, the audio signal processing device comprising:

a receiving unit configured to receive the input audio signal;

a processor configured to generate an output audio signal by binaural rendering the input audio signal; and

an output unit configured to output the output audio signal generated by the processor,

wherein the processor is configured to:

obtain a first transfer function based on a position of a virtual sound source corresponding to the input audio signal with respect to a listener;

generate at least one flat response having a constant magnitude in a frequency domain;

generate a second transfer function based on the first transfer function and the at least one flat response; and

generate the output audio signal by binaural rendering the input audio signal based on the generated second transfer function.

2. The audio signal processing device of claim 1 , wherein the processor is configured to generate the second transfer function by calculating a weighted sum of the first transfer function and the at least one flat response.

3. The audio signal processing device of claim 2 , wherein the processor is configured to:

determine a weight parameter which is used for the weighted sum of the first transfer function and the at least one flat response, based on binaural effect strength information corresponding to the input audio signal; and

generate the second transfer function based on the determined weight parameter.

4. The audio signal processing device of claim 3 ,

wherein the first transfer function comprises magnitude components in the frequency domain, and

wherein the processor is configured to generate the second transfer function by calculating, for each frequency bin, a weighted sum of the magnitude components and the at least one flat response based on the weight parameter.

5. The audio signal processing device of claim 1 , wherein phase components of the second transfer function are identical to phase components of the first transfer function, corresponding to the respective frequency bins in the frequency domain.

6. The audio signal processing device of claim 1 , wherein the processor is configured to:

determine a panning gain based on the position of the virtual sound source corresponding to the input audio signal with respect to the listener; and

generate the at least one flat response based on the panning gain.

7. The audio signal processing device of claim 6 , wherein the processor is configured to determine the panning gain based on an azimuth value of an interaural polar coordinates indicating the position of the virtual sound source.

8. The audio signal processing device of claim 1 , wherein the processor is configured to generate the at least one flat response based on at least a part of the first transfer function.

9. The audio signal processing device of claim 8 , wherein the at least one flat response is a mean of magnitude components of the first transfer function corresponding to at least some frequencies.

10. The audio signal processing device of claim 1 , wherein the first transfer function is either an ipsilateral head related transfer function (HRTF) or a contralateral HRTF included in an HRTF pair corresponding to the position of the virtual sound source corresponding to the input audio signal.

11. The audio signal processing device of claim 10 , wherein the processor is configured to:

generate each of an ipsilateral second transfer function and a contralateral second transfer function based on each of the ipsilateral HRTF and the contralateral HRTF, and the at least one flat response; and

set a sum of energy levels of the ipsilateral second transfer function and the contralateral second transfer function to be equal to a sum of energy levels of the ipsilateral HRTF and the contralateral HRTF.

12. An audio signal processing method comprising the steps of:

receiving an input audio signal;

obtaining a first transfer function based on a position of a virtual sound source corresponding to the input audio signal with respect to a listener;

generating at least one flat response having a constant magnitude in a frequency domain;

generating a second transfer function based on the first transfer function and the at least one flat response;

generating an output audio signal by binaural rendering the input audio signal based on the generated second transfer function; and

outputting the generated output audio signal.

13. The audio signal processing method of claim 12 , wherein generating the second transfer function comprises generating the second transfer function by calculating a weighted sum of the first transfer function and the at least one flat response.

14. The audio signal processing method of claim 13 , wherein generating the second transfer function comprises:

determining a weight parameter which is used for the weighted sum of the first transfer function and the at least one flat response, based on binaural effect strength information corresponding to the input audio signal; and

generating the second transfer function based on the determined weight parameter.

15. The audio signal processing method of claim 14 ,

wherein the first transfer function comprises magnitude components in the frequency domain, and

wherein generating the second transfer function, the second transfer function is generated by calculating, for each frequency bin, a weighted sum of the magnitude components and the at least one flat response based on the weight parameter.

16. The audio signal processing method of claim 12 , wherein phase components of the second transfer function are identical to phase components of the first transfer function, corresponding to the respective frequency bins in the frequency domain.

17. The audio signal processing method of claim 12 , wherein generating the flat response comprises:

determining a panning gain based on the position of the virtual sound source corresponding to the input audio signal with respect to the listener; and

generating the at least one flat response based on the panning gain.

18. The audio signal processing method of claim 17 , wherein determining the panning gain comprises determining the panning gain based on an azimuth value of an interaural polar coordinates indicating the position of the virtual sound source.

19. The audio signal processing method of claim 12 , wherein generating the flat response comprises generating the at least one flat response based on at least a part of the first transfer function.

20. The audio signal processing method of claim 19 , wherein the at least one flat response is a mean of magnitude components of the first transfer function corresponding to at least some frequencies.