I've noticed a strange error in the time stamp when I take videos with my phone.  A Google search has not led me to others experiencing the same problem, so I'm posting it here so that the problem will be "out there" in case someone comes along.

The photo and video time stamps seem to be consistent and accurate, until I change time zones.  When I do, my phone automatically updates its time to reflect local time, which is exactly what I want it to do.  Whatever time stamps my photos apparently grabs the system time, because they show the correct local time.  However, the videos do not.

When I shot videos in St. Louis, Missouri, which is on Central Time, their time stamp was still on Eastern Time—one hour ahead.  When I took videos in Switzerland, the time stamp acted as if I were still back in the U.S., on Eastern Time:  it was six hours behind.

As long as I am aware of the problem, I can easily correct the time because my file naming convention includes the date and time.  I just have to remember to add or subtract for the videos, and that's usually easy enough because otherwise they appear out of sequence.  That's how the problem came to my attention in the first place.

But what I'm really curious about is why the photos have the correct time and the videos don't.  It's the same camera that takes them both.  The only logical place for the software to get the time is from the phone's system time.  But obviously whatever stamps the videos is doing something altogether different.  Well, not altogether:  the minutes and seconds are correct.  It's just the hour that's wrong, and it's clearly a time zone effect.

If anyone comes by here looking for answers, I don't have them.  But at least you'll know that someone else has had the problem.  And if anyone comes by with solutions, thanks in advance!

Posted by sursumcorda on Saturday, October 10, 2015 at 8:50 am | Edit
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Programmatically working with dates and times can be a complicated and frustrating endeavor, at least for me (and the scores of people posting questions on Stack Overflow). One convention for dealing with these complexities is to use Coordinated Universal Time (UTC) in code, but provide options for local differentials. The local time is then calculated from UTC.

That does not always solve all problems, though. I am currently working to fix a bug on a system that has local differential options. All times are calculated from UTC and timestamp fields use the correct "2015-10-10T16:29:34" format. It works great except that one timestamp originates from another system using the same format, but with the time in Eastern. Thus, my system is subtracting four hours and showing an incorrect time.

None of this really addresses your issue, but does perhaps illustrate how strange timestamp anomalies can occur. You raise some good questions. Why do videos apparently use a different function than photographs to calculate time zones? Why is Eastern time cached somewhere on your device when the network time is clearly available, correct and otherwise used? Really, if you had said that your video timestamps were in UTC this would make a lot more sense.

Sorry that I cannot help any despite the verbose response.



Posted by David July on Saturday, October 10, 2015 at 5:02 pm
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