XMP sidecar reading and writing

[colings]

I'm working with XMP sidecar files, and I'm trying to match the formatting from another application that uses exiv2. I've figured out how to read in the xmp file and view/modify the data, but I want to be able to pass options on write (specifically omitPacketWrapper and useCompactFormat). I see those values are in the bindings, but I assume it's just something swig brought over automatically vs having a purpose. Looking at the code, Exiv2::XmpParser::encode is being ignored for binding, and it's what the application is using.

Is there any other way to pass options for how to write the xmp?

[jim-easterbrook]

I'm on holiday at the moment, so can't give you a properly researched answer. I think libexiv2 has a function/method to extract the XMP packet, which might have those options. Then you could write the packet to a file with normal Python file handling.

[jim-easterbrook]

Looking at the libexiv2 API I think Exiv2::XmpParser::encode (https://exiv2.org/doc/classExiv2_1_1XmpParser.html#afad88c80404f9f35b687b33fe9ea9c63) might be what you want. This is currently not included in the Python interface - I didn't think it was needed and its interface does not appear to be easily adapted to Python.

I'll have a go at making a Python interface to this function. Do you need the decode function as well?

[jim-easterbrook]

First step in adding Exiv2::XmpParser::encode is in commit 3ac5f9c.

[colings]

I was able to read in the xmp with the image loading code path, so I shouldn't need decode. If you figured out a clean way to get encode bound it would be a nice companion though, for encoding and decoding directly from strings instead of files. If the encode/decode stuff just doesn't map well to Python though I understand if you don't want to add something hacky to the library.

…

On Thu, Jul 23, 2026, 11:38 AM Jim Easterbrook ***@***.***> wrote: Looking at the libexiv2 API I think Exiv2::XmpParser::encode ( https://exiv2.org/doc/classExiv2_1_1XmpParser.html#afad88c80404f9f35b687b33fe9ea9c63) might be what you want. This is currently not included in the Python interface - I didn't think it was needed and its interface does not appear to be easily adapted to Python. I'll have a go at making a Python interface to this function. Do you need the decode function as well? — Reply to this email directly, view it on GitHub <#66?email_source=notifications&email_token=AAEEVVERIWLHHV33ZJ6Z2MT5GI5RBA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZXGU2DEMBUUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-17754204>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAEEVVEGNBGQQENRA6ZJU5D5GI5RBAVCNFSNUABIKJSXA33TNF2G64TZHMZTSNRSG44TKNBSHNCGS43DOVZXG2LPNY5TCMBUGQ4TENBVUF3AE> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AAEEVVBNHSTFXAECLI5ZWMT5GI5RBA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZXGU2DEMBUUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVJTG633UMVZF62LPOM> and Android <https://github.com/notifications/mobile/android/AAEEVVDBHPV6NSGRFPOOEW35GI5RBA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZXGU2DEMBUUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVZTG633UMVZF6YLOMRZG62LE>. Download it today! You are receiving this because you authored the thread.Message ID: ***@***.*** .com>

[jim-easterbrook]

The MemIo class allows reading & writing XMP data from/to Python bytes, but if you need omitPacketWrapper and useCompactFormat then encode is the only way.

I wrote "Not everything in libexiv2 is available in the Python interface. If you need something that's not there, please let me know." in the readme, so I should honour that commitment. It won't be hacky, I promise.

[colings]

Hey Jim, I just got back to this today and saw you rolled out a new version with this change. I just finished testing it and it worked great, thank you!