dST_choose_segments.m

function [startsSec,stopsSec] = dST_choose_segments(hdr,ftype)

% dt_choose_segments.m
%
% Divide acoustic data into smaller chunks to prevent over-committing memory
% Find a reasonable length of data to handle taking into account that the
% interleaved channels will also be read. To ensure that analysis
% is continuous across a segment, we make sure that the time split
% time is some multiple of the frame rate.

switch ftype
    
    case 1 % wav files
        % Figure out how long the file is by summing up all the bytes
        starts = 0;
        stops = sum(hdr.xhd.byte_length)/hdr.xhd.ByteRate;
        fftSize = 2^ceil(log2(hdr.fs *  .01));
        
        frameAdvanceSec = fftSize / hdr.fs; % this should now be used instead of
        % p.frameLengthSec because it has more precision
        
        chooseMB  = 45; % Based upon empirical performance on a 1 GB machine.
        chooseSamples = chooseMB * 1024 * 1024 / 8;  % change into samples
        chooseSec = chooseSamples / hdr.fs;  % translate into time
        maxTimeSec = frameAdvanceSec * floor(chooseSec/hdr.nch/frameAdvanceSec);
        
        labLength = stops-starts;
        segmentsRequired = ceil(labLength/maxTimeSec);  % # segments per interval
        
        startsSec = zeros(sum(segmentsRequired), 1);
        stopsSec = zeros(sum(segmentsRequired), 1);
        newIdx = 1;
        
        % Step through starts, and if multiple segments are required to handle an
        % interval, add intermediate starts/stops, so you end up with smaller
        % chunks.
        for oldIdx = 1:length(starts)
            for k=1:segmentsRequired(oldIdx)
                startsSec(newIdx) = starts(oldIdx) + ((k-1)*maxTimeSec);
                stopsSec(newIdx) = min(startsSec(newIdx)+ maxTimeSec-1/hdr.fs, stops(oldIdx));
                newIdx = newIdx+1;
            end
        end
        
    case 2 % xwav files
        dnum2sec = 60*60*24;
        starts = hdr.raw.dnumStart;
        stops = hdr.raw.dnumEnd;
        startsSec = (starts - starts(1)).*dnum2sec;
        stopsSec = (stops - starts(1)).*dnum2sec;
end