Add the musicbrainz_releasetrackid tag

[mineo]

We decided to call it musicbrainz_releasetrackid at the summit (https://wiki.musicbrainz.org/MusicBrainz_Summit/13#Elephant_IDs). The commit adding it to Picard is metabrainz/picard@04c3035 so you can just reuse the tag names for all the different formats.

[sampsyo]

Looks great; we should definitely add this.

We can also consider following Picard's lead and changing our internal recording ID name from mb_trackid to mb_recordingid (although this would be a bit of a DB migration headache).

[mineo]

Something that I just thought about because people were talking about duplicates in #mb: if this gets implemented, it would be a good idea to have the duplicates plugin check this tag instead of mb_trackid in https://github.com/sampsyo/beets/blob/master/beetsplug/duplicates.py#L116 because mb_trackid is not really a good indicator for duplicate files.

[mineo]

I'm not sure how up to date the bpd plugin is with compatibility to the real MPD, but the real one will support this tag in 0.19 (http://git.musicpd.org/cgit/master/mpd.git/commit/?id=5525ea45a4e1765db110a8ca5abbc3ca5e66a89a).

[Rawrmonkeys]

What is the status on this? I see that #2690 has some discussion.

Is there anything getting in the way of adding support for the musicbrainz_releasetrackid tag and tossing the possible DB change of mb_trackid -> mb_recordingid into it's own issue?

[sampsyo]

Yep, just adding the recording ID would be totally fine. Any help would be appreciated.

[Rawrmonkeys]

You mean the release track id?

[sampsyo]

Oops, yes!

[arcresu]

It looks to me like this has been implemented and can be closed now, so I'll do so. If I've missed something and that's not the case, please repoen this or leave a comment :)