Add 'starring' the current playing track

[vansoest]

Many MPD clients has already a implemented starred like functionality in the GUI: e.g.: gmpc has a nice heart, at the moment the client show me 'Not implemented'.

[kingosticks]

GMPC accomplishes this by adding the tracks to a playlist called Favorites which it attributes special meaning to and does some extra processing on (i.e. setting the heart icon for songs). Mopidy doesn't yet support playlist modification, hence the 'Not implemented' error message.

If you wanted a generic favourite/rating system it would seem that stickers are the intended way to implement this extended metadata functionality within the MPD protocol (but Mopidy doesn't currently support stickers either). GMPC used to use stickers for ratings but it's since been removed. However, there's been some recentish activity regarding a sticker standard for interoperability.

To support the generic feature in the LocalBackend you'd need to store the extra metadata in the tag cache somehow (#44); maybe the scanner could also extract it from the Popularimeter ID3 tag? Or perhaps it's better suited as a LocalBackend tag cache extension (#369)?

If it's only wanted for Spotify, then once Mopidy has better support for playlist management, it could be a special case for the Spotify backend to star/unstar tracks that the user has added/removed from the "Starred" playlist.

Personally I think adding a generic favourite/favorite/rating field to Mopdiy's Track model would be useful but I don't know where in the core API you'd want to expose modify it.

[adamcik]

Echonest has the concepts of favorite, banned and a 1-10 rating among other things. Think these are candidates to be mapped into mopidy as well as part of this. Either with explicit support for one or more of these, or via a generic metadata lookup api as suggested in #263

[blacklight]

In general, I would find really useful to have the possibility of modifying Spotify's playlists from mopidy (I think "Starred" is just a special playlist). So far it's the only missing feature that sometimes makes me still stick to the "traditional" (buggy) Spotify Linux client.

[reconmaster]

Perhaps this conversation for rathing support for beets may be useful? Using something like rating= would allow for some sort of robust support between different player clients?