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% spec.m
% Jean Marc Valin
%
% Spectrogram function for Octave
%
% Copyright (c) John-Marc Valin 2012
%
% Redistribution and use in source and binary forms, 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.
%
% - Neither the name of Jean Marc Valin nor the names of its
% contributors may be used to endorse or promote products derived from
% this software without specific prior written permission.
%
% 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 FOUNDATION 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 X = spec(x, Fs, framesize, start, stop)
gr=[zeros(1024,1),[0:1023]'/1023,.68*[0:1023]'/1023];
%gr=[.4*[0:1023]'/1023,[0:1023]'/1023,.68*[0:1023]'/1023];
%t=[0:1023]'/1023;
%t=(1+.25*t-cos(pi*t))/2.25;
%gr = [zeros(1024,1),t,.68*t];
%colormap(gr);
if nargin < 2 || isempty(Fs)
Fs = 44100;
end
if nargin < 3 || isempty(framesize)
framesize = 2048;
endif
offset = framesize/8;
X = 20*log10(abs(specgram(x, framesize, 48000, blackmanharris(framesize)', framesize-offset)));
XM=max(max(X));
X = max(XM-30,X);
%size(X)
F = -[framesize/2-1:-1:0]/framesize*Fs;
%F = [0:127]/128*24000;
T=[1:size(X,2)]/Fs*offset;
%imagesc(X(end:-1:1,:));
if nargin < 4 || isempty(start)
istart=1;
else
istart = round(start*Fs/offset);
end
if nargin < 5 || isempty(stop)
istop = size(X,2);
else
istop = round(stop*Fs/offset);
endif
istart = max(1,istart);
istop = min(istop, size(X,2));
imagesc(T(1+istart:istop), F, X(end:-1:1,1+istart:istop));
X = X(:,1+istart:istop);
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