[FieldTrip] Reading brainvision data: problem with channel's resolution

[Ricardo Moura]

Dear all,

I am very new to fieldtrip and I am experiencing a problem when reading
brainvision data. I searched in the mailinglist archives but I didn't find
anything that could help me. In case there is information about it
somewhere else, I would appreciate if someone can send me a reference.

The problem is the following. I am tring to read continuous data from the
brainvision analyzer (already preprocessed), but I always have an error
which seems to be due to a problem with the identification of the channels
resolution. I exported the data from brainvision in ".dat" vectorized
format, and I am loading it first with the ft_preprocessing command.

Here is the command I am running to load it:
cfg = [];
cfg.dataset = 'Raw Data Inspection.dat';
eegData = ft_preprocessing(cfg)


Then the following warning message is returned, for each of the 56 channels
I have in the data:
Warning: Unknown resolution for channel 55 in Raw Data Inspection.vhdr!
> In fileio\private\read_brainvision_vhdr at 50
  In ft_read_header at 381
  In ft_preprocessing at 394


And at the end, I have the following error:
??? Index exceeds matrix dimensions.

Error in ==> read_brainvision_eeg at 150
    dat(chan,:) = tmp(begsample:endsample);

Error in ==> ft_read_data at 400
    dat = read_brainvision_eeg(filename, hdr.orig, begsample, endsample,
chanindx);

Error in ==> ft_preprocessing at 573
      dat = ft_read_data(cfg.datafile, 'header', hdr, 'begsample',
begsample, 'endsample', endsample, 'chanindx', rawindx,
      'checkboundary', strcmp(cfg.continuous, 'no'), 'dataformat',
cfg.dataformat)


Interestingly, when I read the header file with the "hdr =
ft_read_header('Raw Data Inspection.vhdr')", it says that I have only 80
samples in the data. When checking the header file with the notepad, it
says that there are actualy 797740 data points.

So, am I realling doing it right?
Thank you very much in advance, and best wishes,
Ricardo
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20130214/618aff5d/attachment-0001.html>