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function ft_realtime_signalproxy(cfg)
% FT_REALTIME_SIGNALPROXY creates some random data and writes it to a FieldTrip buffer.
% The FieldTrip buffer is a network transparent server that allows the acquisition
% client to stream data to it. An analysis client can connect to read the data upon
% request. Multiple clients can connect simultaneously, each analyzing a specific
% aspect of the data concurrently.
% Use as
% ft_realtime_signalproxy(cfg)
% with the following configuration options
% cfg.blocksize = number, in seconds (default = 0.5)
% = cell-array with channel names
% cfg.fsample = sampling frequency
% cfg.speed = relative speed at which data is written (default = 1)
% cfg.precision = numeric representation, can be double, single, int32, int16 (default = 'double')
% The target to write the data to is configured as
% = string, target destination for the data (default = 'buffer://localhost:1972')
% = string, default is determined automatic
% You can apply some filtering to the random number data to make it
% appear slightly more realistic with
% cfg.lpfilter = 'no' or 'yes' lowpass filter (default = 'no')
% cfg.hpfilter = 'no' or 'yes' highpass filter (default = 'no')
% cfg.bpfilter = 'no' or 'yes' bandpass filter (default = 'no')
% cfg.lpfreq = lowpass frequency in Hz
% cfg.hpfreq = highpass frequency in Hz
% cfg.bpfreq = bandpass frequency range, specified as [low high] in Hz
% To stop this realtime function, you have to press Ctrl-C
% Copyright (C) 2009-2011, Robert Oostenveld
% This file is part of FieldTrip, see
% for the documentation and details.
% FieldTrip is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
% FieldTrip is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% GNU General Public License for more details.
% You should have received a copy of the GNU General Public License
% along with FieldTrip. If not, see <>.
% $Id$
% set the defaults
if ~isfield(cfg, 'target'), = []; end
if ~isfield(, 'headerformat'), = []; end % default is detected automatically
if ~isfield(, 'dataformat'), = []; end % default is detected automatically
if ~isfield(, 'datafile'), = 'buffer://localhost:1972'; end
if ~isfield(cfg, 'blocksize'), cfg.blocksize = 0.5; end % in seconds
if ~isfield(cfg, 'channel'), = ft_senslabel('eeg1020'); end
if ~isfield(cfg, 'fsample'), cfg.fsample = 250; end % in Hz
if ~isfield(cfg, 'speed'), cfg.speed = 1 ; end % relative
% set the defaults for filtering
if ~isfield(cfg, 'lpfilter'), cfg.lpfilter = 'no'; end
if ~isfield(cfg, 'hpfilter'), cfg.hpfilter = 'no'; end
if ~isfield(cfg, 'bpfilter'), cfg.bpfilter = 'no'; end
if ~isfield(cfg, 'lpfiltord'), cfg.lpfiltord = []; end
if ~isfield(cfg, 'hpfiltord'), cfg.hpfiltord = []; end
if ~isfield(cfg, 'bpfiltord'), cfg.bpfiltord = []; end
if ~isfield(cfg, 'lpfilttype'), cfg.lpfilttype = 'but'; end
if ~isfield(cfg, 'hpfilttype'), cfg.hpfilttype = 'but'; end
if ~isfield(cfg, 'bpfilttype'), cfg.bpfilttype = 'but'; end
if ~isfield(cfg, 'lpfiltdir'), cfg.lpfiltdir = 'twopass'; end
if ~isfield(cfg, 'hpfiltdir'), cfg.hpfiltdir = 'twopass'; end
if ~isfield(cfg, 'bpfiltdir'), cfg.bpfiltdir = 'twopass'; end
if ~isfield(cfg, 'debug'), cfg.debug = 'no'; end
if ~isfield(cfg, 'precision'), cfg.precision = 'double'; end
% translate dataset into datafile+headerfile = ft_checkconfig(, 'dataset2files', 'yes');
ft_checkconfig(, 'required', {'datafile' 'headerfile'});
hdr = [];
hdr.Fs = cfg.fsample;
hdr.label =;
hdr.nChans = length(;
hdr.nSamples = 0;
hdr.nSamplesPre = 0;
hdr.nTrials = 1;
blocksmp = round(cfg.blocksize*hdr.Fs);
count = 0;
prevSample = 0;
stopwatch = tic;
onlinefilter = strcmp(cfg.lpfilter, 'yes') + strcmp(cfg.hpfilter, 'yes') + strcmp(cfg.bpfilter, 'yes');
if onlinefilter>1
error('you cannot specify more than one filter')
if onlinefilter
% Nyquist frequency
Fn = hdr.Fs/2;
if strcmp(cfg.lpfilter, 'yes')
Flp = cfg.lpfreq;
N = ft_getopt(cfg, 'lpfiltord', 4);
[B, A] = butter(N, Flp/Fn);
elseif strcmp(cfg.hpfilter, 'yes')
Fhp = cfg.hpfreq;
N = ft_getopt(cfg, 'hpfiltord', 4);
[B, A] = butter(N, Fhp/Fn, 'high');
elseif strcmp(cfg.bpfilter, 'yes')
Fbp = cfg.bpfreq;
N = ft_getopt(cfg, 'bpfiltord', 3);
[B, A] = butter(N, [min(Fbp)/Fn max(Fbp)/Fn]);
% initialize the filter model
FM = ft_preproc_online_filter_init(B, A, zeros(hdr.nChans, 1));
% this is the general BCI loop where realtime incoming data is handled
while true
% increment the number of samples
hdr.nSamples = hdr.nSamples + blocksmp;
begsample = prevSample+1;
endsample = prevSample+blocksmp;
% remember up to where the data was read
prevSample = endsample;
count = count + 1;
fprintf('processing segment %d from sample %d to %d\n', count, begsample, endsample);
% create a random data segment
dat = randn(hdr.nChans, blocksmp);
switch cfg.precision
case 'double'
% keep the data as it is
case 'single'
dat = single(dat);
case 'int32'
dat = int32(dat);
case 'int16'
dat = int16(dat);
ft_error('unsupported value for cfg.precision');
% wait for a realistic amount of time
% apply some filters
if onlinefilter
[FM, dat] = ft_preproc_online_filter_apply(FM, dat);
if strcmp(cfg.lpfilter, 'yes'), dat = ft_preproc_lowpassfilter (dat, hdr.Fs, cfg.lpfreq, cfg.lpfiltord, cfg.lpfilttype, cfg.lpfiltdir); end
if strcmp(cfg.hpfilter, 'yes'), dat = ft_preproc_highpassfilter(dat, hdr.Fs, cfg.hpfreq, cfg.hpfiltord, cfg.hpfilttype, cfg.hpfiltdir); end
if strcmp(cfg.bpfilter, 'yes'), dat = ft_preproc_bandpassfilter(dat, hdr.Fs, cfg.bpfreq, cfg.bpfiltord, cfg.bpfilttype, cfg.bpfiltdir); end
% from here onward it is specific to writing the data to another stream
if strcmp(cfg.debug, 'yes')
fprintf('sample time = %f, clock time = %f\n', endsample/hdr.Fs, toc(stopwatch));
if count==1
% flush the file, write the header and subsequently write the data segment
ft_write_data(, dat, 'header', hdr, 'dataformat',, 'append', false);
% write the data segment
ft_write_data(, dat, 'header', hdr, 'dataformat',, 'append', true);
end % if count==1
end % while true