Contributions:FilePlayback

Function

The FilePlayback filter allows previously recorded BCI2000 data to be "acquired" into BCI2000 as though it was acquired from an amplifier. This functionality could be useful for testing new algorithms, or generating screenshots or video captures after an experiment.

Parameters

The FilePlayback provides the following parameters:

SourceCh

The number of digitized and stored channels that should be read from the file. This should be equal to or less than the SourceChparameter in the dat file.

SampleBlockSize

The number of samples transmitted at a time. This value does NOT need to match the value stored in the dat file. However, it should be noted that the timing of events during the file playback may change relative to the event timing in the saved file, particularly if the event timing is specified in blocks, and not seconds.

SamplingRate

The data sampling rate. This must match the value in the dat file.

SourceChList

The list of channels that should be acquired from each device. The total number of channels listed should correspond to SourceCh, and should be less than or equal to SourceCh.

Speedup

An integer factor indicating the acquisition speed. For example, if a value of 2 is specified, then the data will be read back twice as fast. Additionally, a value of 0 indicates that there should be no pause in-between blocks of data, and that the data should be acquired as quickly as possible. This playback speed will be limited by the processing capabilities of the computer, including the time required to read the data from the file, and to do any signal processing required by the SignalProcessing module.

FileName

The path to the BCI2000 data file.

SuspendAtEnd

This value indicates whether BCI2000 should Suspend at the end of the file, or if it should loop around to the beginning of the file.

StartTime

The starting time of the file, allowing playback to begin in the middle of the file.

Additional Information

Data Storage

As with any acquisition module, the acquired data will be saved in a new dat file. While this may be desired in some instances, it usually makes sense to disable writing the data, since the raw signal will be identical. Therefore, you can pass --FileFormat=Null to prevent duplicate data being saved.

Data Format

The data is acquired from the file uncalibrated; therefore, it is still necessary to enter appropriate SourceChGain and SourceChOffset values for correct processing.

See also

User Reference:DataIOFilter, Programming Reference:GenericADC Class