Recording simultaneously with two OpenBCI devices

Obtaining data from various hardware devices
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jessicaloke
Posts: 4
Joined: Thu Jan 18, 2018 4:15 pm

Recording simultaneously with two OpenBCI devices

Post by jessicaloke »

Hello all,

I would like to record EEG data using two OpenBCI devices simultaneously. Both participants are presented with the same audio stimulus at a given moment using Presentation.

My questions are -
1. Is it possible to use two devices together?
2. How can both acquisition clients in OpenVibe receive the same trigger from Presentation?

Thank you so much,
jessica

jtlindgren
Posts: 778
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: Recording simultaneously with two OpenBCI devices

Post by jtlindgren »

Hi,

you can use two separate Acquisition Servers, and two Acquisition Clients, and then merge the signal in Designer; however the streams might not be too well synchronized in this case. I've never tried to synchro multiple devices personally, so I'm afraid I don't know how well that goes. There's a box called 'Stream Synchronization' in openvibe that is probably intended for this purpose, but I'm not familiar in its operation.

If you use two acquisition servers at the same time, you need to configure them to use different server ports, and different TCP Tagging ports. You can't have two servers on the same port.


My three cents,
Jussi

ralf
Posts: 1
Joined: Thu Aug 23, 2018 9:15 pm

Re: Recording simultaneously with two OpenBCI devices

Post by ralf »

Hello forum,
given that this reply is a few years old I wanted to touch base about whether anything has changed. My goals are similar. I have multiple smarting devices, which individually work fine with openvibe. But now I am trying to figure out how to plug them together. Of note, I probably will have to record each devices data separately via bluetooth on an individual computer (equipped with a bluetooth receiver) and then send the data over an ethernet cable. I searched the forum a bit but couldn't exactly find how to do this.

My idea would be to try this way
EEG1 -> bluetooth -> PC1 running proprietary AcquisitionSoftware -> LabstreamingLayer (LSL)
EEG2 -> bluetooth -> PC2 running proprietary AcquisitionSoftware -> LabstreamingLayer
Then, I'd use (here I don't know how exactly) the OpenvibeAcquisitionServer to get the data from the LSL and send them over to a OpenvibeDesigner.

I could also try to have two separate acquisition servers
EEG1 -> OpenvibeAcquisitionServer1
EEG2 -> OpenvibeAcquisitionServer2
Then I'd have to send the data from the AcquisitionServers (again, here I am blanking) over the ethernet into an OpenVibeDesigner....

Any ideas are welcome. I am not an engineer but do have a fair amount of coding skills, mostly in python/matlab - not so much networking.

Best, ralf

jtlindgren
Posts: 778
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: Recording simultaneously with two OpenBCI devices

Post by jtlindgren »

Hi Ralf, things have not changed that much, I'm afraid!

Solution #1 would work if you can find a way outside OpenViBE to merge two LSL streams into one stream. The LSL driver in OpenViBE only supports one signal and one stimulation stream. If you get the merge done into one LSL stream, then you can pull it in with the Acquisition Server's LSL driver.

Solution #2 might work if you can get each Smarting device send some sort of 'start' stimulation, which you can then send to the Stream Synchronization box: http://openvibe.inria.fr//documentation ... ation.html and apparently get 4 synchronized streams. I have never used that box myself.

A C++ solution would involve hacking either the Acquisition Server or OpenViBE's LSL driver to take in multiple streams and merge them. This might require some skill. Doing the merge in the LSL driver would be easier than trying to get AS to run two LSL drivers at the same time.

Best,
Jussi

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