frameNCC.m

% Copyright (c) 2012, Jianxia Xue, jxue@cs.olemiss.edu
% All rights reserved.
%
% Redistribution and use in source, with or without 
% modification, are permitted provided that the following conditions are 
% met:
%
%   * Redistributions of source code must retain the above copyright 
%     notice, this list of conditions and the following disclaimer.
%   * Redistributions in binary form must reproduce the above copyright 
%     notice, this list of conditions and the following disclaimer in 
%     the documentation and/or other materials provided with the distribution
%      
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
% POSSIBILITY OF SUCH DAMAGE.

% function [r, lagIndex] = frameNCC(frame)
%   compute the normalized cross-correlation feature
%     of a given frame
% @param[in] frame        - the given frame in time
% @param[out] r             - the resulting NCC in half length as the input frame
% @param[out] lagIndex  - the resulting NCC lag indexes, starting from 0
%
% @author Jianxia Xue
% @version 0.20120229
%
function [r, lagIndex] = frameNCC(frame)
frame=frame(:);

M = ceil(length(frame)/2);
lagIndex = 0:(M-1);

r = zeros(M,1);
for i=lagIndex
    a = frame(1+lagIndex);
    b = frame(i+1+lagIndex);
    r(1+i) = a'*b / sqrt(a'*a * (b'*b));
end