[vlc-devel] Adding an alternative cache key for art

[Francois Cartegnie]

The current art fetcher behaviour:

- Tests if art is in cache using album & arturl || title && arturl
This always fail for items without arturl (DVB channels, streams
playlist, ...)
- Retrieves the arturl from lua scripts logic (musicbrainz, google
image, ...)
- Now the arturl is known, it checks if its hash is in cache
- Otherwise download art

So, we always run the pool of art scripts, although we already
downloaded and cached the art, just because we didn't knew the url earlier.

I'd suggest then:
- adding the possibility of generating a hash per input_item, as soon as
we add that item to the playlist (computed from playlist sd, ...).
For most items, this is possible, just using the uri & title.
- Then, when this hash is set, use it for cache key instead of the one
that would be computed later from arturl.

Francois