OpenViBE forum

Hello,

I've been recording some .ov data on openvibe, using EmotivEPOC on the P300-Speller-xDawn procedure.
However, when I try to use it on Scilab/Matlab, converting it to an .EDF file, I can visualise the raw data, but I cannot see when the stimulus are being sent. Where/how can I read the EDF file and know, on Scilab/Matlab, when the stimulus (target letter) was elicited?

(I need to know when the stimulus is shown to be able to recognise the raw data 300 ms after the stimulus).

Thank you in advance!

Hello Artur,

the EDF Writer box apparently has a stimulation input, so in principle it should be able to write the stimulations to the .edf file. How well this feature has been implemented, we don't know. The box is a contribution. At a glance to the box source code it looks like the stimulations are written to the edf file as text format 'annotations'. Then there's the question how to get the annotations out on the reader side, which is a different question entirely.


Best,
Jussi

So, when trying to read those files on Matlab, I do have this column called "EDFAnnotations", but it does not show when the target letter was flashed during the test, and that is exactly what I need to know. Am I missunderstending the information on the column or this information is not inserted there? In this case, how can I get, on Matlab, when the target letter was flashed?

Thank you.

If it doesnt work, you could try another format like gdf. Gdf readers are available via matlab package eeglab for example.

How did you produce the edf file?

Sorry for the late reply,
Jussi