Problem in understanding the encoded time and uploaded time

[Door]

I downloaded a video which was uploaded from an iphone. That video was uploaded on a social media at 12:27 according to UTC. The encoded time is showing the uploaded time. Here is the metadata.

General
Complete name : xxxx_F04C8D9868.mp4
Format : MPEG-4
Format profile : Base Media
File size : 1.65 MiB
Duration : 6 s 933 ms
Overall bit rate : 1 999 kb/s
Encoded date : UTC 2021-03-20 12:27:54
Tagged date : UTC 2021-03-20 12:27:54

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High
Format level : 3.1
Format settings, CABAC : Yes
Format settings, Reference frames : 2 frames
Codec ID : avc1
Duration : 6 s 933 ms
Bit rate : 1 995 kb/s
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 30.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.072
Stream size : 1.65 MiB (100%)
Title : Core Media Video
Encoded date : UTC 2021-03-20 12:27:54
Tagged date : UTC 2021-03-20 12:27:54
Color range : Limited
colour_range_Original : Full
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Codec configuration box : avcC


But another video which was also uploaded from an iphone (or apple device) is showing different time for encoded and uploaded time.

General
Complete name : xxxxx_2082F13EE9.mp4
Format : MPEG-4
Format profile : QuickTime
File size : 1.01 MiB
Duration : 45 s 547 ms
Overall bit rate : 185 kb/s
Encoded date : UTC 2021-03-05 18:00:24
Tagged date : UTC 2021-03-05 18:00:26
Writing library : Apple QuickTime
com_apple_quicktime_author : ReplayKitRecording
com_apple_photos_originating_signature : AVlLrRLb6uJfR+gMSY2qyF4DqeGt
com_apple_quicktime_creationdate : 2021-03-06T02:43:04+09:00

Video
ID : 2
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High
Format level : 1.3
Format settings, CABAC : Yes
Format settings, Reference frames : 2 frames
Codec ID : avc1
Duration : 45 s 547 ms
Bit rate : 53.0 kb/s
Width : 264 pixels
Clean aperture width : 264 pixels
Height : 76 pixels
Display aspect ratio : 3.474
Frame rate mode : Variable
Frame rate : 21.121 FPS
Minimum frame rate : 10.000 FPS
Maximum frame rate : 60.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.125
Stream size : 295 KiB (29%)
Title : Core Media Video
Encoded date : UTC 2021-03-05 18:00:24
Tagged date : UTC 2021-03-05 18:00:26
Color range : Full
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
Codec configuration box : avcC

Audio
ID : 1
Format : AAC LC
Format/Info : Advanced Audio Codec
Codec ID : mp4a-40-2
Duration : 45 s 448 ms
Source duration : 45 s 488 ms
Bit rate mode : Constant
Bit rate : 128 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 kHz
Frame rate : 43.066 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 710 KiB (69%)
Source stream size : 710 KiB (69%)
Title : Core Media Audio
Encoded date : UTC 2021-03-05 18:00:24
Tagged date : UTC 2021-03-05 18:00:26


My question is - why sometimes the uploaded time and encoded time is different and same? What this encoded time actually means here? On another note, a little question is why these 2 metadata is showing different types of metadata? Like one is showing the name "apple" but other one don't.

[Budman1]

Encoded and tagged dates are the actual dates that most camera embed in the video metadata. There is one group for General (the whole video), another for Video and yet a third for Audio. These are usually set by the camera that produced them and have nothing to do with uploaded times or Windows Created,Modified or last accessed times.
Encoded/Tagged dates are usually in UTC time while the others are local times or the times the destination attaches as uploaded times.

These Eocoded/Tagged dates only get changed if someone or some program modifys the video Metadata

[Door]

Thank you for the help! Yes I'm aware of that encoded date and tagged date are always showed in UTC time and others are in local time. The 2nd metadata I have shared its encoded date is only 5 mins different than the uploaded time. Usually on that social platform encoded time are just the same as uploaded time. This is why I'm curious why there is a difference between 2 metadata, especially the formats both are very different. Both are coming from same device and uploaded on a same platform. Is this difference occuring because someone consented to show extra information or someone edited that?

[Budman1]

Many upload sites recode their videos to conform to their specifications. I can only guess that the 2nd video which has non typical frame rate and aspect was re-encoded.

[Door]

Thank you again! Btw is there anyway to tell if a file is coming from its originating device or not by looking at the metadata?

[Budman1]

It all depends on if the video was changed and what was used to change it. Some encoders copy all the netadata, some parts of it and some even drop the metadata all together.

I guess the closest way is to check mediainfos information on both videos. Some attributes usually get changed no matter what encoder is used. If its a direct copy, the 2 videos should match.