We have just recently started using Brainstorm.
We noticed that the when we upload a dataset up on brainstorm using .mat file, the dataset time increases to 14547.967s, when we only recorded for 2 hours (~7200s).
We have tried other file formats such as .dat file and when we had recorded for 90min (~5400s) we were only able to get a read out of ~300s.
It looks like we are looking at the frames from epoch when we compare to the read out from EEGLAB.
These files were originally converted from open ephys file to .mat using the following script:
If you take a look at the screenshots below:
when we open it in EEGLAB it shows the correct time (s) that was recorded.
However when we upload it to brainstorm the time changes and from 2hr to almost 4 hrs. If you also take a look at MATLAB in the workspace the timestamps shows the similar value as the time in seconds but the decimal value is different.
We tested with other files and it looks like the timestamp value is being inserted into the time (s). However this is not correct insertion is there a way to have the correct time (s) output?
We have noticed that the timestamp is usually 2x the value of the time recorded. Why might this be?
I noticed before and when I tried to look up the difference between
create a link to raw data vs import raw eeg
from the resources I found it said there was no difference between which method I use to import the raw data.
However since I can only adjust the sampling frequency via the latter just wanted to know if there were further differences or reasons to choose one vs the other method.
Reviewing, creates a link to the raw data, and it does not modified in any manner. As mentioned in the tutorial, most of the pre-processing (filters and artifact removal happens when in the raw data) then you can turn on and off SSP and ICA components and see their impact in the signals. Moreover, in the specific case for data coming from Matlab .mat files, as in your case, reviewing automatically generates a binary (.bst) file with the data in the mat file. Reading from the binary file instead of the mat file, allows reading only the data to be plotted, instead of reading the entire file, thus it's possible to explore long recordings without using all the memory in the computer.
Importing is used once your data is pre-processed. It will created copies of the data in the Brainstorm database. The import options allow to import segments of the raw data, either by time, or by events (option that is useful to extract epochs/trials).
The recommendation is to use review if pre-processing will be performed on the data. This is also true if the data is already pre-processed, but stills need to be epoched.
