Encoding of events in biomedical signal processing

Events are an important part in Biomedical signal processing. Mostly, events are stored in a separate channel with 16 bits, in pairs of timestamp/event, in triples of timestamp/event/channel or in quadruples of timestamp/event/channel/duration.

Here, we propose a two-byte (16 bit) coding scheme for events. In case the data format for the events contains more than 16 bits, the event code should be stored in the least significant 2 bytes. The first version of proposed codes is presented in Table 1.

Dataformats:

The most most recent revision of the table of event codes can be obtained from [2]:

Software:

The idea of this document is to standardize the encoding of events in biomedical signals.

It will be supported by the BioSig-tools [1] according to Table 2. Other software vendors are invited to use this encoding scheme.

Table 2: Encoding of Events in BIOSIG. M indicatets the number of different eventtypes.

Description	units	Field in Header struct	Remark

Number of events		HDR.EVENT.N(1)	Optional
timestamp	samples	HDR.EVENT.POS(1:HDR.EVENT.N)	Required
event	[see Table 1]	HDR.EVENT.TYP(1:HDR.EVENT.N)	Required
channel		HDR.EVENT.CHN(1:HDR.EVENT.N)	Optional
duration	samples	HDR.EVENT.DUR(1:HDR.EVENT.N)	Optional
Description of event code		HDR.EVENT.CodeDesc(1:M)	Optional
IndexCode for corresponding event		HDR.EVENT.CodeIndex(1:M)	Optional

References:

[1] Alois Schlögl, BIOSIG, http://biosig.sf.net/. 2003-2009.

[2] https://sourceforge.net/p/biosig/code/ci/master/tree/biosig4matlab/doc/eventcodes.txt