EEP - Signal Data Files

Signal Data Files

The filename extension "cnt" was introduced by the NeuroScan acquisition software and stands for "continuous EEG data file".

In EEP, "cnt" is used as the general shortcut for several variants of signal data files. In this context "cnt" means only: a file which somehow allows to retrieve/store

a signal matrix (N_channels * N_samples sample points in max. 32 bit signed accuracy)
unit and amplitude axis scaling factors for each channel
a unique label for each channel (channel labels in EEP are evaluated case insensitive, must not be longer than 10 characters and must consist of the allowed characters only (letters, digits, '-', '+' and '_'; NO whitespaces, parentheses, punctuations...)
one common time axis scaling factor for all channels
optionally, a list of time/code pairs (better known as "triggers" or "events")

Currently, these fileformats are valid input to the cnt... programs:

Name Extension Description
NeuroScan (ns) cnt the data files produced by our NeuroScan SynAmps amplifier software;
read only, output is converted to riff

EEP 2.0 (eep) cnt the file format of the DOS EEP 2.0 software (a proprietary, slightly modified version of an older NeuroScan file format)
EEP 3.x (riff) cnt the highly recommended proprietary EEP 3.x format;
files are compressed to about 1/3 of the size, compared with the other two cnt variants

EEP average avr the ERP matrix files used in the EEP software;
read only, output is converted to riff

Each of the formats above can contain data which are not needed/maintained by EEP modules. They try to keep these data unchanged. Other things are not 100% portable between the formats.

In summary, it's possible to read each filetype listed above with the cnt... programs, but you should use the compressed format whenever possible and you cannot rely on any little detail in any format.

Name	Extension	Description
NeuroScan (ns)	cnt	the data files produced by our NeuroScan SynAmps amplifier software; read only, output is converted to riff
EEP 2.0 (eep)	cnt	the file format of the DOS EEP 2.0 software (a proprietary, slightly modified version of an older NeuroScan file format)
EEP 3.x (riff)	cnt	the highly recommended proprietary EEP 3.x format; files are compressed to about 1/3 of the size, compared with the other two cnt variants
EEP average	avr	the ERP matrix files used in the EEP software; read only, output is converted to riff