b@0: function y = LR2MS(x)
b@0: % LR2MS Converts stereo audio signal to MS (mid side).
b@0: % 
b@0: % by Brecht De Man at Centre for Digital Music, 4 June 2013
b@0: 
b@0: if min(size(x)) ~= 2
b@0:     error('Function LR2MS needs a stereo audio input file.');
b@0: end
b@0: 
b@0: y = zeros(size(x));
b@0: 
b@0: % M = L+R, S = L-R
b@0: y(:,1) = x(1,:) + x(2,:); % mid
b@0: y(:,2) = x(1,:) - x(2,:); % side
b@0: 
b@0: % normalise if necessary
b@0: if max(max(abs(y))) >= 1
b@0:     y = y/max(max(abs(y)));
b@0: end
b@0: 
b@0: end