Prerecorded DAT file as source

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TBlakely
Posts: 4
Joined: 05 Mar 2008, 03:21

Prerecorded DAT file as source

Post by TBlakely » 05 Mar 2008, 03:27

Heya Gerv, Jurgen!

Just curious... have you or anyone you know of written a signal source module that will read in a BCI2000 DAT file as real-time data? I'm happy to write it myself, but figured I'd check to see if I would be wasting a week re-inventing the wheel in doing so.

-Tim Blakely

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

pre-recorded data

Post by gschalk » 05 Mar 2008, 22:30

Tim,

With predictable regularity, this question comes up every few months. We have not done this to date, and that for several reasons.

First, 'replaying' a session does not generally work. For example, application modules may randomize target presentation (so that in replayed mode, the prerecorded EEG would be inappropriate), and in user-paced trials, trials may actually take longer during the simulated session so that their duration exceed the duration of the prerecorded EEG.

Second, this capability would invite people to 'simulate' performance of different parameter combinations on individually recorded (i.e., small) datasets. This is generally a very bad idea since analyses should be based on significant amounts of data and not individual runs.

Having said this, there are some legitimate reasons for wanting to do this, and several users have written specialized modules for this.

Gerv

TBlakely
Posts: 4
Joined: 05 Mar 2008, 03:21

Post by TBlakely » 06 Mar 2008, 16:30

I see, thanks for the clarification. The only reason it would be nice to have is so that we can compare the online performance on a specific dataset to known results from Matlab analysis. In short, we would like to ensure that our new signal analysis module is giving us results that we expect to see from a given dataset previously analyzed offline with Matlab.

mellinger
Posts: 1114
Joined: 12 Feb 2003, 11:06

Post by mellinger » 10 Mar 2008, 05:58

Tim,

do I understand correctly that you designed a signal processing algorithm in Matlab, then implemented it into a BCI2000 filter, and now would like to test whether that filter does what it is supposed to?

The BCI2000 command line environment allows you to link your filter into an executable, and to send existing data through a pipe formed from such executables, which might be what you need. For a reference with examples, see
http://www.bci2000.org/wiki/index.php/U ... Processing

In case you do not only intend to check the signal processing module's output but need to simulate cursor movement and target classification as well, the you should add the ConditionalIntegrator and StateTransform filters to your pipe:
http://www.bci2000.org/wiki/index.php/U ... Integrator
http://www.bci2000.org/wiki/index.php/U ... eTransform

If there are any further questions, please post.

Regards,
Juergen

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