BioSemi.nl

I've received the following error a couple of times:

Error 6004 occurred at File Size in Header does not match Actual File Size. Possible reason(s): Reader will use actual File Size, Please Proceed.

When I open the file in bdf reader or Besa the data looks very unusual. I see mostly solid sections of color (unable to see clear EEG signals) then the signals seem to come back down and then solid sections again, and this repeats throughout the file.

I can't seem to figure out why it happens, my notes for the EEG session indicate that nothing out of the ordinary happened, and during collection the EEG looked fine. Is there a way to fix the header file so the data will look normal again? And do you know of a way to prevent this from happening in the future?

Thanks,
Mallory Hall

The usual cause for a wrong file size in the header is that the recording was not stopped normally (but instead by a PC crash, full harddisk, etc.).

If the file is basically correct, and the problem is just in the header, then you can repair the file with the tool available from http://www.biosemi.com/download/RepairTool.zip

However, your report that BDF-reader cannot show the EEG data suggest that the data itself is corrupted (BDF reader ignores the wrong header value). The symptoms you describe were reported one time earlier by another customer, were the cause was eventually tracked down to a harddisk problem. If ActiView does show clean data, and does not report any errors during the recording itself, then a harddisk problem is the most likely cause.

Which version of ActiView are you using ? Please upgrade to the latest version (there is a bug related to the file writing in version 5.34 and older),

Best regards, Coen (BioSemi)