[Eeglablist] Neuroscan .cnt files

[Dwight Peterson]

Hi Kimberly,

       What is your sampling rate?  I had a similar issue when I was
sampling at an excessive rate (files sizes were also like 1 or 2 GB).  I
have recently downsampled the data via a few matlab scripts we wrote in our
lab.  This made the process much faster regarding importing EEG files into
EEGLAB.  Downsampling the data and saving into a .mat file will probably
help, and then you can import your downsampled data file into EEGLAB.   I
have not used Neuroscan, rather we have an old 8 channel system that
records the EEG (24 bit A>D converter) using Audacity at a rate of 48000
Hz.  This is way too high for EEG data, so we downsample our files from
48000 Hz to 1000 Hz after the raw data file has been exported.  This might
help.   There is also a couple memory settings in the EEGLAB GUI that you
might mess with pertaining to memory issues/options. However, I think you
need to downsample.  There are a few matlab functions, such as decimate.m
that might help you with this downsampling process.

--Dwight--


On Sun, Jan 20, 2013 at 1:28 PM, Kimberly Talboom <kwingert1009 at yahoo.com>wrote:

> Good afternoon,
>
>
> Our laboratory's .cnt files are 3.5 GB give or take a GB depending on the
> research paradigm, and I am having a really difficult time getting the
> files to open in EEGLAB. Neuroscan can open smaller files but has also had
> issues exporting large data files to EEGLAB.
>
> To attenuate the issues with RAM availability and file size, Neuroscan
> suggested that I:
>
>
> 1) Down-sample when I can
> 2) I guess there is a compiled version of EEGLAB (i.e., rather than
> interpreted code) that may help, but is not recommended?
>
>
> I can get the files to open, but it takes an hour, and then it takes
> another hour each time I press a button.
>
> I am running an i7 (laptop)/ i5 (desktop), both are 64 bit 4GB RAM. I have
> the 64 bit version of MATLAB.
>
>
> If anyone has had a similar problem and has found a way around it, I would
> appreciate the help.
>
>
>
> Thank you,
>
> Kimberly Talboom
>
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-- 
Dwight J. Peterson, M.A.
Graduate Assistant
Cognitive and Brain Sciences
Department of Psychology/296
Memory and Brain Laboratory
University of Nevada, Reno
Reno, NV 89557
Cellular: 319-231-8596
Laboratory: 775-682-8667
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