Niklas Haas authored Jan 26, 2021 and Jean-Baptiste Kempf committed Feb 06, 2021

Upstream libplacebo added support for dav1d integration directly,
allowing us to vastly simplify all of this code. In order to take
advantage of new optimizations, I had to allow update_frame to unref the
Dav1dPicture. (This is fine, since double unref is a no-op)

In addition, some of the functions we use were deprecated in recent
libplacebo versions, so since we're taking a new dependency we might as
well fix the deprecation warnings.