The development of the ID3 tag format seems to have stalled if not ceased altogether, not least because most new downloads and rips use other container formats than MP3, notably ISO MPEG 4 part 14 (MP4/MOV) and Matroska (MKV), which come with their own metadata formats, although an ID3v2 tag may be embedded as well.
However, I think there would still be some merit in updating ID3. For instance, neither the official site nor the Github repository documents all the predefined v1 genres actually supported by players (and MP3Tag of course). Another task would be the incorporation of the later Chapter and Accessibility amendments. Also, it would be nice if there were more direct mappings to MP4/QuickTime tag fields, at least as far as they relate to audio content. Finally, our collective experience should reveal some shortcomings of the current design and identify missing predefined tag fields.
In conclusion, is there anyone interested in helping to reboot ID3 development? Would @Florian be interested in being the first adopter of new features that would result from this community activity?
Which feature are you missing from ID3v2.4? What kind of custom tag fields do you use that could be of wider interest?
PS: I havenʼt reached out to the original creators and maintainers yet, except for adding issues and pull requests to the repository, which have been ignored so far.