(windows) command line m4a tagger?

[skeptic Mike]

(23-11-2017 10:20)simoncn Wrote:  Thanks for the test file. The new version of MinimServer (not yet released) is reading the multivalued SINGER tag correctly:

SINGER=Christopher Purves
SINGER=Roberta Invernizzi
SINGER=Sonia Prina

I'm not sure why you think mp4 tags are in such a mess. The spec supports multiple values for all tag names and there are taggers and servers that correctly implement the spec.

Thankyou, that's most helpful.

I think that mp4 tags are ok, it's the difficulty I've had finding tagging programs that work, and support multiple values. I think that relates to the difficulty with identifying the formal specification, and confusing it with the iTunes tag set - which seem to be a specific implementation. Obviously my requirement for a command line tagger makes the search more difficult. However, most of the GUI taggers I've tried don't support multiple values. Perhaps I've not looked at the right ones. mp3Tag will quietly destroy the compliant tags I've (accidentally) produced. I guess I should submit a bug report to mp3tag about that.

Is there a list of taggers that correctly implement the full spec that Minimserver can use?

Brief testing of puddletag on my poor server shows that it will produce multiple tags (in the mutagen format) The UI looks rather like mp3tag, and allows one to add arbitrary tags in the same way.