Previous File Exchange Formats

There have been some file exchange formats which have not obtained or even tried to obtain a status as an official standard but which have been used to exchange biosignal data. These have been studied by members of the File Exchange Format task force but as each one of them has had some limitations, a new format needed to be designed.

"European Data Format"

An earlier, unofficial storage format intended especially for sleep recordings was published in "Kemp B., Värri A., Rosa A.C., Nielsen K.D., Gade J., A simple format for exchange of digitized polygraphic recordings, Electroencephalogr. Clin. Neurophysiol., Vol. 82, 1992, 391-393". This format is often referred to as the "European Data Format", EDF or EDF-92. Display and conversion programs (MS-DOS and Windows-95/NT) for this format can be found in the ftp server sigftp.cs.tut.fi in the directory /pub/eeg-data/programs in the file eurodata.lzh which is an archive file to be opened by lha.exe with the command
LHA E EURODATA.LZH
on a MS-DOS personal computer. Additional information concerning this package can be read from the file euroread.me A program to display EDF-92 files under Windows-95 or Windows NT 4.0 is EDFVIEW which is available in the same directory in the zip archive edfview.zip. Bob Kemp in Leiden, Holland maintains a list of tools and support for EDF.

Extensible Biosignal Format (EBS)

This format has been developed in the Institute for Physiology and Experimental Pathophysiology (IPB) in University of Erlangen-Nürnberg, Germany particularly for the recording of multiple channels of EEG or MEG with the same sampling frequency in all channels. The specification of the EBS data format is available through WWW by following the links of the IPB WWW server at http://www.ipb.uni-erlangen.de/.

SIGIF

SIGIF is a rather flexible data format from university of Porto, Portugal. A document of it has been pulished in
IEEE Transactions on Biomedical Engineering, vol. 44, no. 5, pp. 413-418, May 1997.

IFFPHYS

This format has been developed in co-operation of University of Los Angeles, California and researchers in Australia. Documents on this format can be downloaded via ftp from the ftp server sigftp.cs.tut.fi in the directory /pub/eeg-data/programs in the file iffphys.ps which is a PostScript file to be printed directly with a PostScript printer. The file iffvideo.ext in the same directory contains a short description of a video extension to the format.

Others

CEN/TC251 has produced a prestandard (ENV 1064) for the storage of ECG signals in routine electrocardiography. This prestandard (Standard Communications Protocol - Computer-Assisted Electrocardiography) is very ECG specific and can be used as a reference for future work with other signals and measurements.

ASTM has published a data format for the storage of neurophysiological signals and measurements. The disadvantage of this format is that data is stored in ASCII which is inefficient for biosignals.

Massachusetts Institute of Technology (MIT) has published a database of ECG arrhytmias in digital form. The data format in which the signals have been stored is freely available.

Siemens-Elema, Sweden has made an open specification for storing biomesurements called SIFOR. The disadvantage of this specification is that the structure of binary data is not specified exactly and the sender and the receiver of the data have to be informed about it in advance before data exchange can happen.

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Alpo Värri

Institute of Signal Processing, Tampere University of Technology, P.O. Box 553, FIN-33101 Tampere, Finland
Tel. +358-3-31152575, Fax. +358-3-31153857, E-mail: varri@cs.tut.fi.