Start_time format in .mat file
that value represents the absolute time offset from the 30th of December, 1899. The way MATALB stores the absolute time is a bit different from the way it's done in Delphi, so we should first convert this channel to a number that means something to MATLAB. I've attached an image which shows you how to do that.
If you want to get each time stamp in the absolute format, you can convert it into the number of days, which is done by diving with a a factor of (24*60^2) and then add each point to the absolute time offset.
I think that you should be able to get the correct time using the syntax in the attached image. Let me know if you need anything else.