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not EDF compliant (Physical Maximum)

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eabouzeid +0 points · 4 months ago

Hi,

While trying to open the CHAT Polysomnography .edf files (with both pyEDFlib code and EDFBrowser app) , an important number of files do not open and throw the following error:

  • pyEDFlib code: "OSError: the file is not EDF(+) or BDF(+) compliant (Physical Maximum)"
  • EDFBrowser app: "Physical maximum of signal 34 is equal to physical minimum File is not a valid EDF or BDF File"

I believe the issue is that according to the EDF specifications, the digital minimum must be different from the digital maximum (could be to avoid zero division). The question I have is how to fix it and make the file usable?

An example of such files is the chat-baseline-300039.edf

Please let me know.

Thank you

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mrueschman +0 points · 4 months ago

I see what you mean - it looks like all the EDFs received from one of the CHAT sites/beds have this quirk. Unfortunately, many PSG manufacturers do not follow the EDF specifications to the letter. Other tools like Polyman and Luna do not seem to have issue opening these files.

Based on my reading of the EDF FAQ Q8 is that you could theoretically put dummy values in the physical min/max (i.e. rewrite this part of the EDF header for affected files) to overcome this issue.

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eabouzeid +0 points · 4 months ago

Thanks for the info. There are an important number of files with this issue (80 out of 454 in Baseline; 111 out of 407 in Followup) so changing the physical min/max manually is tedious. Do you know of any programmatic way to change the physical min/max (pyedflib functions are failing to operate on these files)?

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