[FieldTrip] reading EDF+ annotation channel with FieldTrip

[Ingrid Nieuwenhuis]

Hi

I would like to read in EDF+ data with FieldTrip, including triggers 
that are coded in the annotation channel. FieldTrip has recently been 
updated to be able to read EDF+ data (Thanks Robert!). Before, FieldTrip 
could only read EDF data (so then it could not read events which are 
coded on the annotation channel). However, in the EDF+ data that I have 
(which is generate by Net Station software, EGI company), the events on 
the annotation channel are not read in correctly. I asked EGI support 
for the definition they use to write the events to the annotation 
channel in the EDF+ format as is produced by Net Station, and I got this 
answer from one of their technicians:

- Each annotation channel contains a time keeping TAL for each 
EDF+ block, which is +blockTime[20][20][0]

Then, it contains each event for the block, in this format.
         +startTime[21]duration[20]name[20][0]

All times are in seconds. The values in [ ] are the numbers that are 
written into the binary file, and are described in the EDF+ specification.

My knowledge on reading in data and the EDF+ format is not sufficient to 
understand this. I would like to update read_edf (in private of fileio) 
to also be able to read in the EGI version of EDF+ data. Does anyone 
know how to do this? Any help would be greatly appreciated.

And while I'm at it, are there any other EGI users on the list that are 
or will be using the new MFF data format? I would like to use this new 
data format in FieldTrip, but so far FieldTrip can't read it in yet. Did 
anyone already write some code to read this format in that we could 
include into FieldTrip? Also, I've just created a "getting started with 
EGI data <cid:part1.04070304.09070603 at berkeley.edu>" page on the 
FieldTrip wiki. I'll document my experiences there. Everyone else with 
relevant info is (as allways) invited to help fill it.

Thanks a lot,

All the best,
Ingrid

-- 
Ingrid Nieuwenhuis PhD
Sleep and Neuroimaging Laboratory
Department of Psychology
University of California, Berkeley
California 94720-1650

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