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1 % specgrm - Time-Varying Spectrum
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2 %
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3 % specgrm ::
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4 % X:[[T]] ~'signal of length T',
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5 % N:natural | H:[[N]] ~'window length or window',
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6 % M:natural ~'hop size',
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7 % options {
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8 % fs :: nonneg/1 ~'sampling rate';
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9 % range:: [[2]] ~'range for tfdimage'
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10 % }
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11 % -> [[1+N/2,floor(T/M)]] ~'sequence of short term spectra'.
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12 %
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13 % Examples:
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14 % Y1=specgram(x,hanning(256),128,'fs',44100)
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15 %
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16 % Side Effects
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17 % Image Plot of the spectrogram if no output
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18
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19 function y=specgrm(x,w,m,varargin)
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20 if length(w)==1, H=ones(w,1);
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21 else H=w; end
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22 if nargin<3 m=[]; end
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23
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24 n = length(H); if isempty(m), m=n/2; end
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25 if n>m, bufargs={'nodelay'}; else bufargs={}; end
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26 y = powspec(diag(sparse(H))*buffer(zeropad(n-m,x),n,n-m,bufargs{:}));
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27
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28 % Make Spectrogram Display if no arg out
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29 if nargout==0
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30 opts=options('fs',1,'range',13.5,varargin{:});
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31
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32 tfdimage(y,n,m,opts.fs,opts.range,opts);
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33 clear y;
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34 end
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35
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36
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