How Can I Change Mime Type In the Metadata on File

Question

I want to change the "MIME Type" in the file:

└──╼ $exiftool realshort.mp4
ExifTool Version Number         : 12.10
File Name                       : realshort.mp4
Directory                       : .
File Size                       : 98 kB
File Modification Date/Time     : 2021:01:19 23:53:01+00:00
File Access Date/Time           : 2021:01:19 23:53:01+00:00
File Inode Change Date/Time     : 2021:01:19 23:53:01+00:00
File Permissions                : rw-r--r--
File Type                       : MP4
File Type Extension             : mp4
MIME Type                       : video/mp4
Major Brand                     : MP4  Base Media v1 [IS0 14496-12:2003]
Minor Version                   : 0.0.0
Compatible Brands               : isom, 3gp4
Movie Header Version            : 0
Create Date                     : 2014:11:05 13:51:33
Modify Date                     : 2014:11:05 13:51:33
Time Scale                      : 1000
Duration                        : 1.20 s
Preferred Rate                  : 1
Preferred Volume                : 100.00%
Preview Time                    : 0 s
Preview Duration                : 0 s
Poster Time                     : 0 s
Selection Time                  : 0 s
Selection Duration              : 0 s
Current Time                    : 0 s
Next Track ID                   : 3
Track Header Version            : 0
Track Create Date               : 2014:11:05 13:51:33
Track Modify Date               : 2014:11:05 13:51:33
Track ID                        : 1
Track Duration                  : 1.20 s
Track Layer                     : 0
Track Volume                    : 0.00%
Image Width                     : 320
Image Height                    : 240
Graphics Mode                   : srcCopy
Op Color                        : 0 0 0
Compressor ID                   : avc1
Source Image Width              : 320
Source Image Height             : 240
X Resolution                    : 72
Y Resolution                    : 72
Compressor Name                 : 
Bit Depth                       : 24
Video Frame Rate                : 30.02
Matrix Structure                : 1 0 0 0 1 0 0 0 1
Media Header Version            : 0
Media Create Date               : 2014:11:05 13:51:33
Media Modify Date               : 2014:11:05 13:51:33
Media Time Scale                : 48000
Media Duration                  : 1.17 s
Handler Type                    : Audio Track
Handler Description             : SoundHandle
Balance                         : 0
Audio Format                    : mp4a
Audio Channels                  : 1
Audio Bits Per Sample           : 16
Audio Sample Rate               : 48000
XMP Toolkit                     : Image::ExifTool 12.10
Media Data Size                 : 95268
Media Data Offset               : 4610
Image Size                      : 320x240
Megapixels                      : 0.077
Avg Bitrate                     : 636 kbps
Rotation                        : 0

If I do: exiftool -artist=ii realshort.mp4 i can add artist tag with the value ii

But if I do: exiftool -"mime type"=ii realshort.mp4 it won't work

I looked at:
https://libre-software.net/edit-metadata-exiftool/

And also here:
How do you change the MIME type of a file from the terminal?

But I can't find any answer

How can I make it work?

Answer 1

You can't change the MIME type. It's not embedded data. It's a tag derived from what the type of file is.

You could edit try editing the .Exiftool_Config file if you have one (see the example config) to override the base definition, but that will only change what exiftool displays. Another program or another computer will output MP4 as the MIME type.