vo_opengl: add smoothmotion frame blending

SmoothMotion is a way to time and blend frames made popular by MadVR. It's
intended behaviour is to remove stuttering caused by mismatches between the
display refresh rate and the video fps, while preserving the video's original
artistic qualities (no soap opera effect). It's supposed to make 24fps video
playback on 60hz monitors as close as possible to a 24hz monitor.

Instead of drawing a frame once once it's pts has passed the vsync time, we
redraw at the display refresh rate, and if we detect the vsync is between two
frames we interpolated them (depending on their position relative to the vsync).
We actually interpolate as few frames as possible to avoid a blur effect as
much as possible. For example, if we were to play back a 1fps video on a 60hz
monitor, we would blend at most on 1 vsync for each frame (while the other 59
vsyncs would be rendered as is).

Frame interpolation is always done before scaling and in linear light when
possible (an ICC profile is used, or :srgb is used).

1 files changed, 4 insertions, 1 deletions

diff --git a/video/out/gl_video.h b/video/out/gl_video.h
index b287658bef..f62a292785 100644
--- a/video/out/gl_video.h
+++ b/video/out/gl_video.h
@@ -53,6 +53,8 @@ struct gl_video_opts {
     int chroma_location;
     int use_rectangle;
     struct m_color background;
+    int smoothmotion;
+    float smoothmotion_threshold;
 };
 
 extern const struct m_sub_options gl_video_conf;
@@ -69,7 +71,7 @@ void gl_video_config(struct gl_video *p, struct mp_image_params *params);
 void gl_video_set_output_depth(struct gl_video *p, int r, int g, int b);
 void gl_video_set_lut3d(struct gl_video *p, struct lut3d *lut3d);
 void gl_video_upload_image(struct gl_video *p, struct mp_image *img);
-void gl_video_render_frame(struct gl_video *p, int fbo);
+void gl_video_render_frame(struct gl_video *p, int fbo, struct frame_timing *t);
 struct mp_image *gl_video_download_image(struct gl_video *p);
 void gl_video_resize(struct gl_video *p, struct mp_rect *window,
                      struct mp_rect *src, struct mp_rect *dst,
@@ -84,6 +86,7 @@ void gl_video_resize_redraw(struct gl_video *p, int w, int h);
 
 void gl_video_set_gl_state(struct gl_video *p);
 void gl_video_unset_gl_state(struct gl_video *p);
+void gl_video_reset(struct gl_video *p);
 
 struct gl_hwdec;
 void gl_video_set_hwdec(struct gl_video *p, struct gl_hwdec *hwdec);