function y = MS2LR(x)
% LR2MS Converts stereo audio signal to MS (mid side).
% 
% by Brecht De Man at Centre for Digital Music, 4 June 2013

if size(x,2) ~= 2
    error('Function MS2LR needs a stereo audio input file.');
end

y = zeros(size(x));

% L = (M + S)/2, R = (M-S)/2
y(:,1) = (x(:,1)+x(:,2))/2; % left channel
y(:,2) = (x(:,1)-x(:,2))/2; % right channel

end