Errors validating webp image

[tritium]

Hi there and thanks for this awesome tool!
i'm trying to add a valid EXIF UserComment tag containing some human readable JSON formatted text to a webp image but encountering some errors when i try to validate it using ExifTool.
i'm using piexifjs to create the exif data and node-webpmux to load the webp and set it.

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Warning                         : [minor] Improper EXIF header
Exif Byte Order                 : Big-endian (Motorola, MM)
Warning                         : Non-standard format (string) for ExifIFD 0x9286 UserComment
Warning                         : Value for ExifIFD tag 0x9286 UserComment overlaps IFD
Warning                         : Invalid EXIF text encoding for UserComment
Unsure what is causing it.
What is strange is that while ExifTool(and Metadata++ ofc) is freaking out some other online tools do show the UserComment field as if it was a valid and recognized EXIF tag eg:
https://jimpl.com/results/uSrEKUk4jizCNyeh4jUNZCfS?target=exif
Attached are image and HTML hex dump.
Any tips pointing me in the right direction are appreciated.
Have a great Sunday.
Thanks!

[Phil Harvey]

It sounds like you need to read the EXIF specification.  Also, take a look at the file using the exiftool -htmldump output to try to make sense of this mess.

- Phil

[tritium]

Thanks Phil,

managed to fix everything BUT this error, i am a bit stumped.

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Warning                         : [minor] Improper EXIF headerI am using the Piexif library to inject this header

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"Exif\x00\x00\x4d\x4d\x00\x2a\x00\x00\x00\x08"Most online exif viewers are able to correctly parse the imageDescription field and its content but not all.
Attached image, htmldump and

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validateoutput

Have a great Week End.

[Phil Harvey]

The EXIF should begin with the TIFF byte-order mark.  Not with the JPEG EXIF Segment header.

- Phil