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"Encoded" and "Tagged" say "UTC" which is more or less the same as the UK winter time/Greenwhich Mean Time (GMT). "creationdate" says "+0200" and matches the Central European Summer Time (CEST, UTC+2h). Now the question would be why you got CEST in the UK, not British summer time (UTC+1h) . Did you check all your systems' time settings?
I was in Italy, which is on CEST.
Is your answer to Q1 "Yes"?
I know Encoded and Tagged are UTC (GMT), but my question Q2 is what are they? IOW where do those two items of data come from and what is their purpose? And Q3?
Terry, East Grinstead, UK
‘Encoded date’ and ‘Tagged date’ are MP4 properties, separate from QuickTime properties, even if they both tell the same thing.
com.apple.quicktime.creationdate is a QuickTime Metadata Key. It has the time zone specified, unlike the ‘Encoded date’ and ‘Tagged date’.
For new recordings (when filming) on iOS, the ‘Encoded date’ should reflect the start time of the recording and the ‘Tagged date’ reflect the end time of the recording (when the tags were added), converted to UTC time.
For conversions, the encoder may set the ‘Encoded date’ and ‘Tagged date’. E.g. ffmpeg sets both to the same time, to whatever you want (now/from source/none at all/custom).
When you take a video (or picture), most cameras video and still types take the Date and time set in the setup for your camera and convert it to UTC time. MP4 (Mov) videos have Encoded (Time video was stored as MP4 (Mov) format), Tagged (Time metadata 'tags' like encoded added). There is also a 'Recorded' (Time video was actually recorded) Tag that is sometime shown. All of these times are either identical or very close, depending on the code in your camera.
The Apple Quicktime metadata time was added by your camera and taken directly from the camera setting. In other words, when you took the video shown by MediaInfo, You were in Italy on June 3rd, 2017 at 12:15:11 which Apple Metadata showed in it's tag. But the Encoded/Tagged time was shown in UTC time June 3rd, 2017 10:15:11. 2 hours difference. If you lived where I do the Encoded time would have been 05:15:11 because I am -5 hour from UTC time and another -2 hours from Italy. -7 hours total.
Windows does the same thing. It posts a Created/Modified Date/Time in LOCAL time, even though the video Encoded/Tagged/Recorded Time is almost always in UTC time.
Bottom line... Apple time is LOCAL... Encoded/Tagged is UTC time
Thanks all, appreciate those helpful replies.
Reckon I'll continue ignoring Tagged and Encoded.