Introduction

EDF+ files are a little bit different from EDF files. EDF+ annotations are perhaps the most important difference between EDF and EDF+ files.edfAnn was designed to handle EDF+ annotations.

Let's consider some objects

• The sleep stages quantified by Rechschaffen and Kales criteria
• The annotations included by the technician describing lights on/off
• The output of an algorithm detecting QRS complexes
• Some marks indicating artifacts to avoid the processing of these segments
• The triggers indicating the presence of some stimulus used to mark the onset time in the averaging process...

All the previous objects (I am sure that you will be able to think in many other examples) have a lot in common. As a matter of fact they can be described using the following marks

• An onset
• A duration (it can be 0 in case of a point annotation)
• A content

We called generically this creature an annotation. The process followed to arrive to the annotation can be very diverse (some examples would be: the output of an algorithm, some complex analysis made by humans, some signal generated by an auxiliary device and many others).

Other physiological formats maintain annotations and signals in different files. EDF+ allows the inclusion of annotations in the same file that contains the signals. This inclusion implies some modifications in the structure of the file that can be somewhat difficult.

edfAnn is a program to import/export annotations between EDF+ and ASCII files. To do it we need a method to write annotations in the ASCII file. edfAnn reads and writes ASCII files with this structure:

onset<TAB>duration<TAB>content<CR>
onset<TAB>duration<TAB>content<CR>
onset<TAB>duration<TAB>content<CR>
...

This structure can be easily created (e.g., as the output of a processing carried out by Scilab, R or Octave) and can be reviewed by humans. Once converted to an annotation signal, the position of the annotations can be reviewed together with the signals and if we have the appropriate software they can be edited (erased/moved/created) by hand. In this process a text file is included in an EDF+ file.

The opposite process is also important: you can have different annotations in the same signal and you want to extract the annotations to get several goals e.g. to separate them in different files or to create a report. In this process a part of an EDF+ file is exported to an ASCII file.

Both processes can by done with edfAnn.

Finally, EDF+ uses a very special empty annotation marking the onset of each data record. In discontinuous EDF+ files (and also in continuous ones) they mark the time at which the data record begins. edfAnn allows the edition of these annotations too.

To compile the program you will need to install Qt. The program was developed on Linux using a Suse 9.0 and 9.1 distribution. Then, it was ported to Windows OS. To compile the sources on Windows, Borland 5.5 and Qt non-commercial (such as they are included at the book the official Qt book,C++ GUI Programming with Qt 3) were used. The source can be compiled with no change. Once more, I think that I fill the requirements of the license so I decided to distribute the binary files too. Of course if this is not the case let me know and I will retire the binary files immediately. Since it is necessary to distribute some dll, and it can be somewhat troublesome, a installer of the Windows binaries ( NIS and HM NIS EDIT) was used.