vf_vapoursynth: save display resolution as a variable

mpv has a generic method for getting the display resolution, so we can
save it in vf_vapoursynth without too much trouble. Unfortunately, the
resolution won't actually be available in many cases (like my own)
because the windowing backend doesn't actually know it yet. It looks
like at least windows always returns the default monitor (maybe we
should do something similar for x11 and wayland), so there's at least
some value. Of course, this still has a bunch of pitfalls like not being
able to cope with multi monitor setups at all but so does display_fps.
As an aside, the vapoursynth API this uses apparently requires R26 (an
ancient version anyway), so bump the build to compensate for this.
Fixes #11510

1 files changed, 1 insertions, 0 deletions

diff --git a/filters/filter.h b/filters/filter.h
index 35a4afac83..8820199a42 100644
--- a/filters/filter.h
+++ b/filters/filter.h
@@ -398,6 +398,7 @@ struct mp_stream_info {
     void *priv; // for use by whoever implements the callbacks
 
     double (*get_display_fps)(struct mp_stream_info *i);
+    void   (*get_display_res)(struct mp_stream_info *i, int *res);
 
     struct mp_hwdec_devices *hwdec_devs;
     struct osd_state *osd;