User Reference:GDFFileWriter
Function
The GDFFileWriter component writes out data in the GDF File Format.
General storage related parameters are described on the DataIOFilter documentation page. The GDFFileWriter provides the same parameters as the EDFFileWriter does. In addition, the GDFFileWriter provides an option to define mappings between BCI2000 state variables and GDF events.
Parameters
EventCodes
BCI2000 does not prescribe the semantics of its state variables. GDF, on the other hand, associates a fixed set of events with certain numeric codes. Thus, a general mapping of BCI2000 states onto GDF events is not possible. Instead, GDF events are created via a user-defined set of mapping rules in the EventCode parameter, which also has a set of rules predefined for the most important cases.
The EventCodes parameter is a two-column matrix, with each row associating a boolean expression with a hexadecimal event code as defined in the GDF File Format. The expression is evaluated for each data block; whenever its value switches from "false" to "true", the GDF event code from the second column is entered into the GDF event table.
The default value of the EventCodes parameter defines the most common mappings between BCI2000 states and GDF event codes:
| Condition | Code | GDF Event |
|---|---|---|
| TargetCode!=0 | 0x0300 | trial begin |
| TargetCode==0 | 0x8300 | trial end |
| TargetCode==1 | 0x030c | cue up |
| TargetCode==2 | 0x0306 | cue down |
| (ResultCode!=0)&&(TargetCode==ResultCode) | 0x0381 | hit |
| (ResultCode!=0)&&(TargetCode!=ResultCode) | 0x0382 | miss |
| Feedback!=0 | 0x030d | feedback onset |
Besides GDF events, BCI2000 state variables will also be mapped to additional signal channels the same way as for EDF.
States
None.