Audio signal processing method and device

1. A method for processing an audio signal, the method comprising:

receiving an input audio signal including a multi-channel signal;

receiving filter order information variably determined for each subband of a frequency domain;

receiving block length information for each subband based on a fast Fourier transform length for each subband of filter coefficients for binaural filtering of the input audio signal;

receiving Variable Order Filtering in Frequency-domain (VOFF) coefficients corresponding to each subband and each channel of the input audio signal per block of the corresponding subband, a total sum of lengths of the VOFF coefficients corresponding to the same subband and the same channel being determined based on the filter order information of the corresponding subband; and

filtering each subband signal of the input audio signal by using the received VOFF coefficients to generate a binaural output signal.

2. The method of claim 1 , wherein the filter order is determined based on reverberation time information of the corresponding subband, which is obtained from proto-type filter coefficients, and

the filter order of at least one subband obtained from the same proto-type filter coefficients is different from the filter order of another subband.

3. The method of claim 1 , wherein the length of the VOFF coefficients per block is determined as a value of power of 2 having the block length information of the corresponding subband as an exponent value.

4. The method of claim 1 , wherein the generating of the binaural output signal further comprises:

partitioning each frame of the subband signal into subframe units determined based on the predetermined block length, and

performing fast convolution between the partitioned subframes and the VOFF coefficients.

5. The method of claim 4 , wherein the length of the subframe is determined as a value which is a half as large as the predetermined block length, and

the number of partitioned subframes is determined based on a value obtained by dividing the total length of the frame by the length of the subframe.

6. An apparatus for processing an audio signal for performing binaural rendering of an input audio signal including a multi-channel signal, the apparatus comprising: a fast convolution unit configured to perform rendering of direct sound and early reflection sound parts for the input audio signal, wherein the fast convolution unit is further configured to:

receive the input audio signal,

receive filter order information variably determined for each subband of a frequency domain,

receive block length information for each subband based on a fast Fourier transform length for each subband of filter coefficients for binaural filtering of the input audio signal,

receive Variable Order Filtering in Frequency-domain (VOFF) coefficients corresponding to each subband and each channel of the input audio signal per block of the corresponding subband, a total sum of lengths of the VOFF coefficients corresponding to the same subband and the same channel being determined based on the filter order information of the corresponding subband; and

filter each subband signal of the input audio signal by using the received VOFF coefficients to generate a binaural output signal.