dawn@0: function [Limits] = calculate_Silence( x, fs, frameLength )
dawn@0: 
dawn@0: % Convert mono to stereo
dawn@0: if (size(x, 2)==2)
dawn@0: 	x = mean(x')';
dawn@0: end
dawn@0: [m n]=size(x);
dawn@0: if(m>n)
dawn@0:     x=x';
dawn@0: end
dawn@0: % Window length and step (in seconds):
dawn@0: win = frameLength/fs;
dawn@0: step = win;
dawn@0: 
dawn@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%
dawn@0: %  THRESHOLD ESTIMATION
dawn@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%
dawn@0: 
dawn@0: % Weight = 10; % used in the threshold estimation method
dawn@0: 
dawn@0: % Compute short-time energy and spectral centroid of the signal:
dawn@0: Eor = ShortTimeEnergy(x, win*fs, step*fs);
dawn@0: 
dawn@0: 
dawn@0: % Apply median filtering in the feature sequences (twice), using 5 windows:
dawn@0: % (i.e., 250 mseconds)
dawn@0: E = medfilt1(Eor, 5); E = medfilt1(E, 5);
dawn@0: 
dawn@0: % normalise
dawn@0: 
dawn@0: E = E*(1/max(E));
dawn@0: 
dawn@0: % Get the average values of the smoothed feature sequences:
dawn@0: E_mean = mean(E);
dawn@0: % 
dawn@0: %Find energy threshold:
dawn@0: % [HistE, X_E] = hist(E, round(length(E) / 10));  % histogram computation
dawn@0: % [MaximaE, countMaximaE] = findMaxima(HistE, 3); % find the local maxima of the histogram
dawn@0: 
dawn@0: 
dawn@0: T_E = 0.0005; % determined empirically
dawn@0: 
dawn@0: % Thresholding:
dawn@0: Flags1 = (E>=T_E);
dawn@0: 
dawn@0: flags = Flags1;
dawn@0: 
dawn@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
dawn@0: %  SPEECH SEGMENTS DETECTION
dawn@0: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
dawn@0: count = 1;
dawn@0: WIN = 0;
dawn@0: Limits = [];
dawn@0: while (count < length(flags)) % while there are windows to be processed:
dawn@0: 	% initilize:
dawn@0: 	curX = [];	
dawn@0: 	countTemp = 1;
dawn@0: 	% while flags=1:
dawn@0: 	while ((flags(count)==1) && (count < length(flags)))
dawn@0: 		if (countTemp==1) % if this is the first of the current speech segment:
dawn@0: 			Limit1 = round((count-WIN)*step*fs)+1; % set start limit:
dawn@0: 			if (Limit1<1)	Limit1 = 1; end        
dawn@0: 		end	
dawn@0: 		count = count + 1; 		% increase overall counter
dawn@0: 		countTemp = countTemp + 1;	% increase counter of the CURRENT speech segment
dawn@0: 	end
dawn@0: 
dawn@0: 	if (countTemp>1) % if at least one segment has been found in the current loop:
dawn@0: 		Limit2 = round((count+WIN)*step*fs);			% set end counter
dawn@0: 		if (Limit2>length(x))
dawn@0:             Limit2 = length(x);
dawn@0:         end
dawn@0:         
dawn@0:         Limits(end+1, 1) = Limit1;
dawn@0:         Limits(end,   2) = Limit2;
dawn@0:     end
dawn@0: 	count = count + 1; % increase overall counter
dawn@0: end
dawn@0: 
dawn@0: %%%%%%%%%%%%%%%%%%%%%%%
dawn@0: % POST - PROCESS      %
dawn@0: %%%%%%%%%%%%%%%%%%%%%%%
dawn@0: 
dawn@0: % find the frame index of the start and end frames of non-silent segments
dawn@0: Limits = floor( Limits / frameLength );
dawn@0: pos = find(Limits == 0);
dawn@0: if(pos)
dawn@0:     Limits(pos) = 1;
dawn@0: end
dawn@0:     
dawn@0: % A. MERGE OVERLAPPING SEGMENTS:
dawn@0: RUN = 1;
dawn@0: while (RUN==1)
dawn@0:     RUN = 0;
dawn@0:     for (i=1:size(Limits,1)-1) % for each segment
dawn@0:         if (Limits(i,2)>=Limits(i+1,1))
dawn@0:             RUN = 1;
dawn@0:             Limits(i,2) = Limits(i+1,2);
dawn@0:             Limits(i+1,:) = [];
dawn@0:             break;
dawn@0:         end
dawn@0:     end
dawn@0: end
dawn@0: 
dawn@0: % B. Get final segments:
dawn@0: segments = {};
dawn@0: for (i=1:size(Limits,1))
dawn@0:     segments{end+1} = x(Limits(i,1)*frameLength:Limits(i,2)*frameLength); 
dawn@0: end