BDF(+) file format "Status" channel
Posted: Mon May 02, 2016 1:08 pm
We (Cambridge Electronic Design Ltd) have had an importer for EDF(+)/BDF(+) files for many years, and I was revisiting it recently to incorporate it into an improved file importer system.
I doing this, I discovered that we have no specification for the Status channel signal. We seem to have implemented this in the past by assuming it is a 16-bit signal sampled at the same rate as the waveforms and we detect changes in individual bits to implement up to 16 channels of event times.
However, in testing our code changes, I downloaded your example BDF files (Newtest17-256 and Newtest17-2048) and discovered that in your 24-bit data, bits of the Status channel other than the low 16 bits are changing.
I have searched the web for a definitive statement about the format of Status channels, and have been unable to find this. In fact the only reference is on your BDF file format page, but there is no explanation of this channel:
Note1: Total header length (for BDF and EDF) is: {(N+1)*256} bytes, where N is number of channels (including the status channel).
Do you have any documentation about the format of the Status channel, or can you point meat it elsewhere, please?
I doing this, I discovered that we have no specification for the Status channel signal. We seem to have implemented this in the past by assuming it is a 16-bit signal sampled at the same rate as the waveforms and we detect changes in individual bits to implement up to 16 channels of event times.
However, in testing our code changes, I downloaded your example BDF files (Newtest17-256 and Newtest17-2048) and discovered that in your 24-bit data, bits of the Status channel other than the low 16 bits are changing.
I have searched the web for a definitive statement about the format of Status channels, and have been unable to find this. In fact the only reference is on your BDF file format page, but there is no explanation of this channel:
Note1: Total header length (for BDF and EDF) is: {(N+1)*256} bytes, where N is number of channels (including the status channel).
Do you have any documentation about the format of the Status channel, or can you point meat it elsewhere, please?