Trouble using Classifier Processor for P300 BCI

Concerning processing components: filters, file load/save, visualizations, communication ...
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4emmaliz
Posts: 3
Joined: Tue Jul 20, 2021 8:34 pm

Trouble using Classifier Processor for P300 BCI

Post by 4emmaliz »

Hi,
I am using OpenVibe as a P300-based BCI. I am able to successfully train the classifier, but receive little to no accuracy and this warning when doing online trials:

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[WARNING] Box <Classifier processor> sends inconsistent chunk dates on output [0] (current chunk dates are [98864994766,101441975143] whereas previous chunk dates were [0,0])
 [WARNING] 'Stimulations' streams should have continuously dated chunks
 [WARNING] Please report to box author and attach your scenario
I get this warning when using the provided P300 speller and magic card examples. I just built the latest code from the git to see if it would be resolved, but it is not.

Thibaut
Posts: 264
Joined: Wed Oct 31, 2018 9:14 am

Re: Trouble using Classifier Processor for P300 BCI

Post by Thibaut »

Hi,
This warning is not a problem, stimulations date are a little boring to use and often if you don't pay attention to that you have this kind of warning.
Thibaut

4emmaliz
Posts: 3
Joined: Tue Jul 20, 2021 8:34 pm

Re: Trouble using Classifier Processor for P300 BCI

Post by 4emmaliz »

Hi,
Thanks for the reply. On an older post: viewtopic.php?f=13&t=10179 the similar problem occurred and was fixed. I had the same issue previously, built the latest code that was suggested there, and the problem was solved. I'm not sure why it is occurring again. Is it possible there is another bug with the classifier box?

Thibaut
Posts: 264
Joined: Wed Oct 31, 2018 9:14 am

Re: Trouble using Classifier Processor for P300 BCI

Post by Thibaut »

Hi,
It's not a real bug but yes there is a problem in the code of the classifier processor. The real problem is the check of consistent date for stimulations. For information all stimulation stream must have chunks that start when the previous ones have finished. but the stimuli are not sent every time.
Thibaut

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