can't figure out how to add info to BYTE type fields

[klaussa]

Hi,

I have been trying to figure out the way to convert a string for XPSubject into the required format.
Can anyone please provide more guidance / examples on how the conversion between BYTE to javascrpt Int works ? ( i am considering to put text into subject )

thank you

[hMatoba]

Which value do you want to add?
Example:

var s = "foo";
var bytes = [];
for (var i=0; i<s.length; i++) {
    bytes.push(s.charCodeAt(i));
}

bytes -> [102, 111, 111]

[klaussa]

@hMatoba
I want to add a piece of text to those fields.
// XPTitle: // XPComment: // XPAuthor: // XPKeywords: // XPSubject

The example you provided doesn't output foo but outputs a chinese character :(

I use this to check: http://metapicz.com/#landing ( + also I do windows -> properties -> details tab to check ).

Any advice ?

The Code looks like:

[hMatoba]

It need to encode and decode as UCS2. Read the specification.
http://www.exiv2.org/tags.html

[mdrx-io]

@klaussa finding the answer not straightforward, but this was my solution (using Node.js v12 and the new spread syntax):

exif[piexifjs.ImageIFD.XPTitle]: [...Buffer.from('Your XPTitle', 'ucs2')]

For more information, see:
https://nodejs.org/api/buffer.html#buffer_buffers_and_character_encodings
https://nodejs.org/api/buffer.html#buffer_buffers_and_typedarrays
Other background info:
https://www.npmjs.com/package/punycode
https://mathiasbynens.be/notes/javascript-encoding

[SyedShehzadGillani]

its saying uncaught pack error, when i used [...Buffer.from('Your XPTitle', 'ucs2')] using vue 3 js

[krydos]

In my case this issue happened due to big number in exifObj['GPS'][piexif.GPSIFD.GPSTimeStamp].
But it definitely depends. It can be related to any EXIF field. Not only GPS related.