Method for generating filter for audio signal and parameterizing device therefor

An apparatus for post-processing an audio signal by a binaural renderer, comprising:

• a first processor configured to generate a filter for an audio signal;
• and
• a second processor configured to receive an input audio signal and filter the input audio signal by using one or more parameters generated by the first processor;
• wherein the first processor is configured to:
• receive one or more binaural room impulse response (BRIR) filter coefficients in a time domain corresponding to at least one position in a virtual reproduction space,
• convert the BRIR filter coefficients into a plurality of sets of subband filter coefficients,
• truncate each set of subband filter coefficients based on a filter order value for each subband obtained by at least partially using characteristic information extracted from each set of subband filter coefficients, wherein the filter order value is determined to be variable in a frequency domain, and
• generate fast Fourier transform (FFT) filter coefficients by fast Fourier transforming each set of truncated subband filter coefficients by a predetermined block size in a corresponding subband,
• wherein the second processor is configured to perform block-wise fast convolution on each subband signal of the input audio signal by using the FFT filter coefficients corresponding thereto,
• wherein the predetermined block size is determined to be a smaller value between a first value and a second value,
• wherein the first value is obtained by multiplying a reference filter length of a corresponding set of truncated subband filter coefficients by 2, and
• wherein the second value is a predetermined maximum FFT size.