European Data Format
European Data Format (EDF) is a standard file format designed for exchange and storage of medical time series. A few European medical engineers who first met at the 1987 international Sleep Congress in Copenhagen developed it. EDF was published in 1992. It is widely used for EEG and polysomnography recordings in commercial equipment and multicenter research projects.
EDF stores multichannel data allowing different sample rates for each signal. Internally it includes a header and one or more data records. The header contains information on the whole recording (patient identification, start time...) and on each included signal (filtering, sampling rate...) coded as ASCII characters. The different data records contain samples as little-endian 16-bit integers.
Being an open and non-proprietary format it has been used as an exporting option of commercial devices as well as a vehicle for developing digital signal processing software independent of the acquisition system.
In 2003 an update of EDF (EDF+) allowing coding discontinuous data as well as annotations in UTF-8 format was published .
Main application fields of EDF include Electroencephalography (EEG), electrocardiography (ECG) and sleep recordings. EDF and EDF+ can also be used in a wide range of physiological recordings such as nerve conduction studies, Evoked potentials, EMG and many others.