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Save timestamps along with EEG data in GDF format

Posted: Wed Mar 01, 2017 11:11 am
by Leo_vasc
Hi,

first, I'd like to thank you guys for developing and constantly improving Openvibe, it indeed is a great ressource.
I am running a relatively simple EEG paradigm during which stimulation depends on certain factors of ongoing activity. So far I have used BCIlab or custom Maltab code only but recently switched to Openvibe.
My problem now is fairly simple but I did not find a solution in the frorum or elsewhere yet: While saving data (the result of some algorithm I pass EEG data through online) I would like to save data from all channels PLUS the time information, i.e. the timestamps for each sample. This is crucial for several reasons. When i save data into .csv format this obviously is not an issue since timestamps are included. CSV however is ASCII based and consumes a lot of space on the harddrive, i.e. is not that effeicient. GDF on the other hand is quite efficient and would be perfect but I did not manage to inlcude timpestamps in GDF files yet.
Does someone have a hint on how to do that?

Many thanks in advance,

Leo

Re: Save timestamps along with EEG data in GDF format

Posted: Wed Mar 01, 2017 3:34 pm
by tgaugry
Hi,

There is indeed no timestamp in gdf files.
You can however :
  • Calculate it using sampling rate and sample number
  • Add a time signal into it with the "Time Signal" box and "Signal Merger" box
Hope that helps,