The SSFF track briefly hits the disk, but the return value of this function is in-memory only.
rdaTrackToSsff(rdaPath, columnExpression)Raw contents of an SSFF-encoded file
Path to the Rda file containing the signal track
The R expression needed to extract the desired signal data from the Rda file, for example `data$audio` or `data$velumgridsigUS`