matthiasm@8: 
matthiasm@8: 
matthiasm@8: 
matthiasm@8: 
matthiasm@8: % CQ2HPCP Convert Constant Q spectrum to a HPCP
matthiasm@8: %
matthiasm@8: %   CQ2HPCP(cqframes, info)
matthiasm@8: %
matthiasm@8: %   cqframes = vector or matrix constant q spectrum / spectra
matthiasm@8: %   info = info structure containing parameters
matthiasm@8: %
matthiasm@8: 
matthiasm@8: function [hpcpframes] = mmcq2hpcp(cqframes, info)
matthiasm@8: 
matthiasm@8: %get cq parameters from info structure
matthiasm@8: num_win = info.numberframes;
matthiasm@8: 
matthiasm@8: cqbins = size(cqframes,1); 
matthiasm@8: 
matthiasm@8: bpo = info.binsperoctave;
matthiasm@8: 
matthiasm@8: % calculate the number of octaves we have in the spectrum
matthiasm@8: num_oct = floor(cqbins/bpo)-1;
matthiasm@8: 
matthiasm@8: hpcpframes(1:num_win, 1:bpo) = 0;   
matthiasm@8: 
matthiasm@8: 
matthiasm@8: 
matthiasm@8: % for each window calculate chromagram
matthiasm@8: for i = 1 : num_win
matthiasm@8:     % add each octave of the spectrum into the chromagram
matthiasm@8:     for oct = 0:num_oct;     
matthiasm@8:         ind = oct*bpo;
matthiasm@8:         
matthiasm@8:         hpcpframes(i, 1:bpo) = hpcpframes(i, 1:bpo) + abs(cqframes(ind+1:ind+bpo,i))';   
matthiasm@8:                 
matthiasm@8:     end;
matthiasm@8:  
matthiasm@8:     % normalise
matthiasm@8: %     hpcpframes(i,1:bpo) = hpcpframes(i,1:bpo)/max(hpcpframes(i,1:bpo));
matthiasm@8:     meanc = mean(hpcpframes(i,1:bpo));
matthiasm@8:     if meanc > 0.0000001
matthiasm@8:         hpcpframes(i,1:bpo) = hpcpframes(i,1:bpo)/mean(hpcpframes(i,1:bpo)); %scale to be a distribution!
matthiasm@8:     else
matthiasm@8:         hpcpframes(i,1:bpo) = (bpo)^(-1);
matthiasm@8:     end
matthiasm@8: end;
matthiasm@8: