How are these numbers converted to a readable Date/Time string?

I have 2 XML files I'm reading - one has a date/time attribute that's readable (ex. May 1, 2010 12:03:14 AM) and the other... not so much (ex. 1272686594492). Both files have the complicated date/time format, but only the newer one has the readable version. I cannot figure out how to make the complicated version readable. Any ideas?

The numbers are in the pastbin below.

http://pastebin开发者_StackOverflow社区.com/HMLEAGhf

Thanks!

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Looks like what you have is the number of milliseconds from midnight, January 1st 1970 (which is kind of like UNIX time, except it's in milliseconds, not seconds). For example:

long l = 1272740342854;
DateTime dt = new DateTime(1970, 1, 1).AddMilliseconds(l);
Console.WriteLine(dt);

When I plug that in, it's actually a couple of hours off so I guess there must be some kind of timezone offset applied as well.

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My guess is the number represents the seconds since 1st of january 1970

so 1276648174733 = June 16, 2010 00:29:34

http://www.mbari.org/staff/rich/utccalc.htm