Read BDF (BioSemi Data Format) file

Reads a BDF file and returns a PhysioExperiment object. BDF is a 24-bit extension of the EDF format used by BioSemi systems.

Usage

readBDF(
  path,
  channels = NULL,
  start_time = NULL,
  end_time = NULL,
  resample = FALSE,
  status = TRUE
)

Arguments

path: Path to the BDF file.
channels: Optional character vector of channel names to load. If NULL, all channels are loaded.
start_time: Optional start time in seconds for reading a subset. Note that BDF subsetting is record-granular: start_time/end_time are rounded outward to whole data records (typically 1 s), so the returned signal and any extracted trigger onsets share that record-aligned window (onsets are relative to it and may extend slightly past end_time).
end_time: Optional end time in seconds for reading a subset.
resample: Logical. If FALSE (default) and channels have differing native rates, a MultiRatePhysioExperiment is returned; if TRUE, all channels are resampled to the highest rate (legacy).
status: Logical. If TRUE (default) and a BioSemi "Status" channel is present, stimulus triggers are extracted from it (see bdfTriggerEvents) and attached to the result as events.

Value

A PhysioExperiment, or a MultiRatePhysioExperiment when native rates differ and resample = FALSE.

Details

BDF (BioSemi Data Format) is a 24-bit variant of EDF used by BioSemi acquisition systems. The main differences from EDF are:

24-bit data resolution (vs 16-bit in EDF)
Header starts with 0xFF followed by "BIOSEMI"
Digital range is -8388608 to 8388607

Examples

# Round-trip a small recording through a temporary BDF file
pe <- PhysioExperiment(
  assays = list(raw = matrix(rnorm(400), nrow = 100, ncol = 4)),
  colData = S4Vectors::DataFrame(label = c("A1", "A2", "B1", "B2")),
  samplingRate = 100
)
tmp <- tempfile(fileext = ".bdf")
writeBDF(pe, tmp)

# Read the file back
pe_in <- readBDF(tmp)

# Read only specific channels
pe_sub <- readBDF(tmp, channels = c("A1", "B1"))

unlink(tmp)