FeatureTimeAcfCoeff

computes the ACF coefficients of a time domain signal
> called by ::ComputeFeature
>
> @param x: audio signal
> @param iBlockLength: block length in samples
> @param iHopLength: hop length in samples
> @param f_s: sample rate of audio data (unused)
> @param eta: index (or vector of indices) of coeff result
>
> @retval vacf autocorrelation coefficient
> @retval t time stamp
 ======================================================================

0001 %computes the ACF coefficients of a time domain signal
0002 %> called by ::ComputeFeature
0003 %>
0004 %> @param x: audio signal
0005 %> @param iBlockLength: block length in samples
0006 %> @param iHopLength: hop length in samples
0007 %> @param f_s: sample rate of audio data (unused)
0008 %> @param eta: index (or vector of indices) of coeff result
0009 %>
0010 %> @retval vacf autocorrelation coefficient
0011 %> @retval t time stamp
0012 % ======================================================================
0013 function [vacf, t] = FeatureTimeAcfCoeff(x, iBlockLength, iHopLength, f_s, eta)
0014  
0015     % initialization
0016     % these values are arbitrary - adapt to your use case
0017     if (nargin < 5)
0018         eta = 20;
0019     end
0020 
0021     % blocking
0022     [x_b, t] = ToolBlockAudio(x, iBlockLength, iHopLength, f_s);
0023     iNumOfBlocks = size(x_b, 1);
0024     
0025     % allocate memory
0026     vacf = zeros(length(eta),iNumOfBlocks);
0027     
0028     for (n = 1:iNumOfBlocks)
0029         % calculate the acf
0030         if (sum(x_b(n, :)) == 0)
0031             afCorr = zeros(2*size(x_b, 2)+1,1);
0032         else
0033             afCorr = xcorr(x_b(n, :), 'coeff');
0034         end
0035         afCorr = afCorr((ceil((length(afCorr)/2))+1):end);
0036     
0037         % find the coefficients as requested
0038         vacf(1:length(eta),n) = afCorr(eta);
0039     end
0040 end