It seems that Plex does not properly detect the com.apple.iTunes:ORIGINAL YEAR' freeform tag (presented as ORIGINAL YEAR by ffmpeg).
After searching around the web for a little, it seems that Plex relies on ffmpeg output to determine tags of certain files. I've confirmed with a small script (https://gist.github.com/chrisbenincasa/3b518514fd2b0d3cc494dce82b84b3a7) that setting ----:com.apple.iTunes:ORIGINALDATE on m4a files (mimicking behavior of Vorbis) allows Plex to recognize the tag.
One way to fix this would be to append a second tag for m4a called ORIGINALDATE. I'm not sure what the implications of changing the existing tag would be... It would probably also be beneficial to set ORIGINALYEAR in a separate tag.
It seems that Plex does not properly detect the
com.apple.iTunes:ORIGINAL YEAR'freeform tag (presented asORIGINAL YEARby ffmpeg).After searching around the web for a little, it seems that Plex relies on ffmpeg output to determine tags of certain files. I've confirmed with a small script (https://gist.github.com/chrisbenincasa/3b518514fd2b0d3cc494dce82b84b3a7) that setting
----:com.apple.iTunes:ORIGINALDATEon m4a files (mimicking behavior of Vorbis) allows Plex to recognize the tag.It doesn't seem as if Picard defines a mapping for this field (https://picard-docs.musicbrainz.org/en/appendices/tag_mapping.html) but the popular Typescript music-metadata library has mappings for to
ORIGINALYEARandORIGINALDATE: https://github.com/Borewit/music-metadata/blob/master/doc/common_metadata.mdOne way to fix this would be to append a second tag for m4a called
ORIGINALDATE. I'm not sure what the implications of changing the existing tag would be... It would probably also be beneficial to setORIGINALYEARin a separate tag.