ANT EEprobe .cnt to Openvibe .gdf

[ndpatel]

Hello,

First of all I am new to Openvibe. I was doing all my work with MATLAB. But it seems that Openvibe has very good interface which can save my time to write and modify the code in MATLAB.

My problem is, I am using ANT-Neuro ASAlab to record my data in LAB. Which will generate .cnt files which are no use in Openvibe. I tried to convert it to .gdf using EEGLAB but that files don't have same format as Openvibe use. I am getting error message as below,


I can't upload my file because of 2MB file limit. So I put the file in Skydrive, Please check link below,
http://cid-64b7eb48fc9caf59.office.live ... c/Openvibe

It will be very helpful if anyone suggest me the solution so I can use my .cnt files in Openvibe. Thanx in advance.


Regards,
NEHAL PATEL

[lbonnet]

Hello Nehal, and welcome on board !

First, I tried to read your GDF file and I got the same error as you did.

Code: Select all

[WARNING] At time 0 (0x0)<Box algorithm::GDF file reader> Can't handle GDF files with channels having different sampling rates!

Based on this message, it seems that your GDF file has different sampling frequencies, and the GDF file reader box does not handle this case.
Is it normal regarding what you are using to record the EEG ?
If not, maybe you can check the conversion CNT > GDF in eeglab. Maybe there is some options to check in the process to be called ?
I am not familiar with EEGLAB so I can't be precise about it, I'm sorry.

Laurent-

[yrenard]

Dear ndpatel,

indeed, the GDF file format allows to store multiple streams with different sampling rate. This is not possible in OpenViBE so the GDF file reader simply denies access to the file. I also know there have been a couple of issues reading OpenViBE generated GDF files from EEGLab and/or vice versa. The Brainamp file format is much simpler than the GDF file format so I think you would not have any issue converting your CNT file to brainamp file format w/ EEGLab and then read it back in OpenViBE with the Brainamp File Reader box.

I hope this helps, keep us posted.
Regards,
Yann

[ndpatel]

Dear Laurent & Yann,

Sorry I was just lost hope for converstion after total frustrating and thinking about why ANT develop such a thing !!!!
I tried each things but not worked out and then I asked Dieter Devlaminck because he interfaced same amplifier which we are using, He give me some good suggestion not to try to play that much hard with .cnt > .gdf if I am novice . And I accepted that.

First of all thanx 2 both of you for replies and sorry for checking so late...

@ Laurent, I really appriciate your work to look out my data. Its ok about not having expirience using EEGLAB, I know that you have much more important works to do rather than playing with such Matlab plugins. But I got my emotiv research headset this week, i followed the instruction on that thread for getting aquistion server. but I found svn://scm.gforge.inria.fr/svn/openvibe/trunk/openvibe-applications/acquisition-server/branches/wip-lbonnet-emotiv does not exist anymore. May be you change some steps, if so I will be happy to hear about that from you. I want to interface emotiv headset with openvibe. I posted under other other thread also, just ignore wherever you want. I will keep trackin both so. Thanks...

@ Yann, That data was recorded from ASA lab(weird one) software which we use to interface ant-neuro amplifier. I just take sample rate 256 Hz for all the channels. EEGLAB uses Biosemi which uses Robert Oostenveld *.cnt reader(if I recall correct !!), So which link is broken who knows ??

I am wondering how do I convert .cnt to brainamp file? Because EEG lab import lots of data format but export either .txt,EDF/GDF/BDF. Any sugesstion for conversion to brainamp file will be very helpful. If it's already implemented, I don't want to bother you much. Or I have other option also like directly connecting that amplifier to openvibe skipping that ASA lab (weird again !!) .


Have a great day !!!


Thanks & Regards,
Nehal.

[lbonnet]

@ Laurent, I really appriciate your work to look out my data. Its ok about not having expirience using EEGLAB, I know that you have much more important works to do rather than playing with such Matlab plugins. But I got my emotiv research headset this week, i followed the instruction on that thread for getting aquistion server. but I found svn://scm.gforge.inria.fr/svn/openvibe/ ... net-emotiv does not exist anymore. May be you change some steps, if so I will be happy to hear about that from you. I want to interface emotiv headset with openvibe. I posted under other other thread also, just ignore wherever you want. I will keep trackin both so. Thanks...

Indeed, the emotiv branch doesn't exist anymore
As stated in the FAQ, the Emotiv driver has been merged in the trunk of the software. It means that you don't need to change anything in the build script to build it. Just do a fresh SVN checkout, put the emotiv Research SDK directory in C:/Program Files, and build the software.

I edited the discussion on "Emotiv driver status", so everyone who read that discussion also gets the information.

If you have any problem with the driver, don't hesitate to post on a new dedicated topic, I'll try to help
have fun with EPOC !

Laurent-

[yrenard]

Dear ndpatel,

sorry for late reply, I remember someone who told me he wrote a cnt file reader back a few years ago. I will have to dig in my email archives to find this out and see what can be done. Meanwhile, I think you should directly connect your amplifier to the OpenViBE acquisition server. If it is compatible with ASALab, it should most likely be compatible with our acquisition server.

Hope this helps,
Yann

[TPAC]

Hi,

Openvibe apparently manages GDF files in version V1.25. If you export EEG data from EEGLAB in a GDF file, this will be created using the gdf 2.11 version, which is not readable by Openvibe (you get the warning message indicating the presence of channels with different sampling rates). As a simple workaround, just modify the script writeeeg.m of EEGLAB like following :

HDR.VERSION = 2.11; ==> HDR.VERSION = 1.25;

EEGLAB will then create gdf files readable by Openvibe.

Hope this helps...

[yrenard]

Dear TPAC,

thank you for this tip and welcome on this forum !

Yann