Libav is basically unsupported by mpv, see upstream issues 3923, 3925.
Needs patch to even build, subs are broken and not supported anymore.
I cannot call such state of mpv[libav] stable with a clear conscious.
Upstream's position on libav support leaves little hope the situation
will improve in the future.
Sorry, but mpv[libav] users will have to migrate to ffmpeg, to another
player, send fixes upstream, or live with partly broken functionality.
# This file is only for generic masks. For arch-specific masks (i.e.
# mask everywhere, unmask on arch/*) use arch/base.
+# Ilya Tumaykin <itumaykin+gentoo@gmail.com> (18 Jun 2017)
+# Libav is basically unsupported by mpv, see upstream issues 3923, 3925.
+# Needs patch to even build, subs are broken and not supported anymore.
+media-video/mpv libav
+
# Maciej Mrozowski <reavertm@gmail.com> (15 Jun 2017)
# Mask due to bug #621810
dev-games/simgear gdal