Problem visualizing EOG and EMG of .edf file (normal eeg tracks view)

Francois · May 28, 2018, 6:04pm

I checked the code, and channels with lower sampling rates are indeed ignored when reading from EDF files in Brainstorm. This is probably why you don’t see anything in the EMG and EOG windows.

github.com

brainstorm-tools/brainstorm3/blob/master/toolbox/io/in_fopen_edf.m#L146


    else
        error(['The number of samples is not specified for channel "' hdr.signal(i).label '".']);
    end
end
hdr.signal(i).sfreq = hdr.signal(i).nsamples ./ hdr.reclen;
end
% Find annotations channel
iAnnotChans = find(strcmpi({hdr.signal.label}, 'EDF Annotations'));  % Mutliple "EDF Annotation" channels allowed in EDF+
iStatusChan = find(strcmpi({hdr.signal.label}, 'Status'), 1);        % Only one "Status" channel allowed in BDF
iOtherChan = setdiff(1:hdr.nsignal, [iAnnotChans iStatusChan]);
% Remove channels with lower sampling rates
iIgnoreChan = find([hdr.signal(iOtherChan).sfreq] < max([hdr.signal(iOtherChan).sfreq]));    % Ignore all the channels with lower sampling rate
if ~isempty(iIgnoreChan)
iOtherChan = setdiff(iOtherChan, iIgnoreChan);
end
% Get all the other channels
if isempty(iOtherChan)
error('This file does not contain any data channel.');
end
% Read events preferencially from the EDF Annotations track
if ~isempty(iAnnotChans)

Brainstorm can’t handle signals with mixed sampling rates. It would be possible to reinterpolate the signals with the lower sampling rates using a higher rate, but it would require some consequent rewriting and testing of the current reading functions.
If you are interested in working on this, you are more than welcome than welcome to contribute to the project!