merging BDFs?

[alvin]

Hi,

Do you know any way to merge two BDF files?

greetings!
Jacob

[brroach]

I am wondering the same thing? I suppose along the same lines, can you concatenate more than two .bdf files with this method?

[Coen]

In principle, merging of two files only involves deleting the header of the second file, adding the data section of the second file to the first file, and adjusting the length field in the header of the first file to the new value (total length of the two files). In LabVIEW, the code will be quite simple, and similar to the cropper tool available from http://www.biosemi.com/download/FileCropper.zip (instead of splitting a file in smaller sections, you will now have build a new file from smaller files).

Please note that the current version 7.1 of LabVIEW imposes a file limit of 2 GByte (the reason for the "new file" options in LabVIEW). I am already testing with the new LabVIEW 8. In this new version, there is no file limit anymore. I plan to put a merger tool on the website for download as soon as we will change the customer versions of ActiView to labVIEW 8 (coming spring).

Best regards, Coen (BioSemi)

[Teuniz]

"In principle, merging of two files only involves deleting the header of the second file,
adding the data section of the second file to the first file, and adjusting the length field in the
header of the first file to the new value (total length of the two files)."

Wrong, if you do so, the result will not be BDF compatibel.

The reason is that BDF claims to be EDF with 24-bit resolution.
So, according to the BDF file-format description, the only differences between BDF and EDF
is the samplesize (three bytes instead of two) and the maximum and minimum digital values
in the header -8388608 instead of -32768 etc.
Because the EDF file-format specification says that an EDF-file always contains een
uninterrupted recording, a BDF file must always contain an uninterrupted recording as well.

I suggest that Biosemi adopts BDF+, a 24-bit version of EDF+ which can
contain interrupted recordings. As well more patient-info and annotations/events.

Regards,

Teunis

[Coen]

Formally, you are right. However, in practice it has been allowed to record several segments in a single BDF file since the introduction of the BDF format in 2001. The start of each segment is indicated by a High "epoch" bit in the status/trigger channel (bit 16 in last channel, see http://www.biosemi.com/faq/trigger_signals.htm). The "pause" function in ActiView is used frequently by customers to start/stop a recording multiple times within a single BDF file (with each start indicated automatically by the "epoch" bit) Sorry for causing confusion by not mentioning this departure from the EDF standard explicitly on our website.

So, if you merge two BDF files according to the above guidelines, then every BDF reader currently in use will process the file without any problem.

Best regards, Coen (BioSemi)

[sbanerjee]

Hello,
I am having trouble using merger 8.2 on my Windows 7 machine. Are there any other versions of this?
Thanks

[Coen]

http://www.biosemi.com/download/ToolsFo ... Engine861/

[ayalaall]

Hi

I downloded the Biosemi file merger but I get an error when trying to run it. Do I need to use the latest ActiveView version in order to use the file merger?

Thanks,

Ayala

[Coen]

For RTE 8.2 use http://www.biosemi.com/download/Merger.zip

For RTE 8.6.1 use http://www.biosemi.com/download/ToolsFo ... Engine861/

[myrto]

Hi,
I am interested, too, in merging two .bdf files into one (I had to interrupt the recording to change battery and start a new file for the same participant to continue the experiment) but cannot make out from the above posts how to do it. Are there anywhere available any clear instructions? I have downloaded in my PC Merger86 tool but cannot figure out how to input the two files.

Any help would be appreciated, thanks!

[Coen]

Install RTE 8.6 (http://ftp.ni.com/support/softlib/labvi ... 861STD.exe) and run the merger86.exe

Press "START", select the first and second BDF files from the successive popping up file dialogs, type the target file name in the third popup file dialog, and the merge will run.

Best regards, Coen (BioSemi)