[FieldTrip] processing ANT cnt files with FieldTrip

[Arnaud Delorme]

Dear Dave,

last time I have checked FileIO (the Fieldtrip data importer) will not read ANT trigger files by default (it should read the raw data though - Robert Oostenveld one of the main developer of Fieldtrip was interning at ANT about 10 years ago and wrote the Matlab import function for them).
The anteepimport1.09 is a plugin for the EEGLAB software. It can import events (and then you can save the data in EEGLAB format and reload it in Fieldtrip). You cannot recompile the ANT project (their source files are proprietary and not included).

Hope this helps.
Best wishes,

Arno

On 18 Dec 2012, at 08:59, Dave Britton wrote:

> I am trying to process EEG data in .cnt files obtained from the ANT system. I am using a Linux Xubuntu 12.04 amd64 operating system. I have installed the Linux 64 bit version of FieldTrip.
> 
> What is required to successfully process ANT eeg .cnt and .trg files? The libraries that came with the FieldTrip download did not work as it came from the download, and my investigations led me to what should be the latest version of the ANT import library. I have downloaded the latest ANT eep library, anteepimport1.09/libeep-3.3.167, and run config, make and make install, successfully, but MATLAB cannot find the shared object file it should generate, even when I link the .so.3 file into the same directory as the MATLAB m-file and the MATLAB current directory.
> 
> Initially the system was unable to read the cnt files, which is why I attempted to reinstall the anteepimort library. Is there more to this installation than the standard" configure, make, make install" process? Any clues would be appreciated!
> 
> Dave Britton
> City College of New York
> Psychology Dept.
> 
> Here is the error message I get:
> 
> >> cfg.headerfile = '/home/dave/semanticflanker/data/ANT/20121114_1013.cnt';
> >> cfg.hdr = ft_read_header(cfg.headerfile);
> Invalid MEX-file
> '/home/dave/fieldtrip-20121102/anteepimport1.09/libeep-3.3.167/mex/matlab/read_eep_cnt.mexa64':
> libeep.so.3: cannot open shared object file: No such file or directory
> 
> Error in ft_read_header (line 627)
> hdr = read_eep_cnt(filename, 1, 1);
> 
> Previous efforts before recompiling libeep produced failures that seemed to indicate the read_eep_cnt routine was incorrectly assessing the cnt file size and obtaining garbage, which is why I attempted to rebuild the eepimport library:
> ===== error messages ====
> >> clear;
> % required items for cfg:
> flank1 = 'FLANK1'; % markersA in tutorial walkthru
> flank2 = 'FLANK2';
> target = 'TARGET';
> cfg=[];
> cfg.trialdef.prestim = 0.05; % 50 ms baseline
> cfg.trialdef.poststim = 0.5; % trials last 500 ms
> cfg.trialdef.eventtype = 'input';
> cfg.trialdef.eventalue = target;
> cfg.dataset = '/home/dave/semanticflanker/data/ANT/20121114_1013.cnt';
> cfg.headerfile = '/home/dave/semanticflanker/data/ANT/20121114_1013.cnt';
> cfg.triggerfile = '/home/dave/semanticflanker/data/ANT/20121114_1013.trg';
> cfg.trialfun = 'trialfun_semattn';
> cfg.padding = 2;
> cfg.dataformat = 'ns_cnt32'; % see faq about reading Neuroscan cnt files
> cfg.headerformat = 'ns_cnt32';
> cfg.eventformat = 'ns_cnt32';
> cfg.blockread = 1;
> %
> cfg = ft_definetrial(cfg);
> evaluating trialfunction 'trialfun_semattn'
> Warning: could not determine channel type from the CTF header
> > In ft_chantype at 213
> In ft_read_header at 1711
> In trialfun_semattn at 5
> In ft_definetrial at 162
> Warning: could not determine channel type from the CTF header
> > In ft_chantype at 213
> In ft_read_header at 1711
> In ft_read_event at 600
> In trialfun_semattn at 6
> In ft_definetrial at 162
> found 407 events
> created 132 trials
> the call to "ft_definetrial" took 4 seconds and required the additional allocation of an estimated 13 MB
> Loading file /home/dave/semanticflanker/data/ANT/20121114_1013.cnt ...
> Reading data .....
> Scaling data .....
> Reading Event Table...
> Skipping event table (tag != 1,2,3 ; theoritically impossible)
> Warning: channel labels should not be empty, creating unique labels
> > In ft_read_header at 1684
> In ft_preprocessing at 343
> In semattn_main at 34
> processing channel { '�`RXqwh��' ............(channel data is garbage)....
> 
> ===== end of error messages===
> 
> 
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