vo: do final frame draw only near page flip

Separate passing a new frame to VOs using the new API into two steps.
The first, vo_draw_image(), happens after a new frame is available
from the filter chain. In constrast to old behavior, now the frame is
not actually rendered yet at this point (though possible slice draw
calls can already reach the VO before). The second step,
vo_new_frame_imminent(), happens when we're close enough to the
display time of the new frame that we'll commit to flipping it as the
next action and will not change the OSD over the previous frame any
more.

This new behavior fixes a previous problem with vo_vdpau and vo_gl in
the situation where the player is paused after decoding a new frame
but before flipping it; previously changing OSD in that state would
switch to the new frame as a side effect. It would also allow an easy
way to fix extra output files produced with something like "--vo=png
--frames=1" with precise seeking, but this is not done yet.

The code now relies on a new mp_image from the filter chain staying
valid even after the vf_vo put_image() call providing it returns. In
other words decoders/filters must not deallocate or otherwise
invalidate their output frame between passing it forward and returning
from the decode/filter call.

1 files changed, 4 insertions, 0 deletions

diff --git a/libvo/video_out.h b/libvo/video_out.h
index bd7b2e8fa5..a710f7de4a 100644
--- a/libvo/video_out.h
+++ b/libvo/video_out.h
@@ -63,6 +63,8 @@ enum mp_voctrl {
     VOCTRL_XOVERLAY_SET_COLORKEY,       // mp_colorkey_t
     VOCTRL_XOVERLAY_SET_WIN,
 
+    VOCTRL_NEWFRAME,
+    VOCTRL_SKIPFRAME,
     VOCTRL_REDRAW_OSD,
 
     VOCTRL_ONTOP,
@@ -258,6 +260,7 @@ struct vo {
     int config_count;  // Total number of successful config calls
 
     bool frame_loaded;  // Is there a next frame the VO could flip to?
+    struct mp_image *waiting_mpi;
     double next_pts;    // pts value of the next frame if any
     double next_pts2;   // optional pts of frame after that
 
@@ -307,6 +310,7 @@ int vo_get_buffered_frame(struct vo *vo, bool eof);
 void vo_skip_frame(struct vo *vo);
 int vo_draw_frame(struct vo *vo, uint8_t *src[]);
 int vo_draw_slice(struct vo *vo, uint8_t *src[], int stride[], int w, int h, int x, int y);
+void vo_new_frame_imminent(struct vo *vo);
 void vo_draw_osd(struct vo *vo, struct osd_state *osd);
 void vo_flip_page(struct vo *vo, unsigned int pts_us, int duration);
 void vo_check_events(struct vo *vo);