video/out: always support redrawing VO window at any point

Before, a VO could easily refuse to respond to VOCTRL_REDRAW_FRAME,
which means the VO wouldn't redraw OSD and window contents, and the
player would appear frozen to the user. This was a bit stupid, and makes
dealing with some corner cases much harder (think of --keep-open, which
was hard to implement, because the VO gets into this state if there are
no new video frames after a seek reset).

Change this, and require VOs to always react to VOCTRL_REDRAW_FRAME.
There are two aspects of this: First, behavior after a (successful)
vo_reconfig() call, but before any video frame has been displayed.
Second, behavior after a vo_seek_reset().

For the first issue, we define that sending VOCTRL_REDRAW_FRAME after
vo_reconfig() should clear the window with black. This requires minor
changes to some VOs. In particular vaapi makes this horribly
complicated, because OSD rendering is bound to a video surface. We
create a black dummy surface for this purpose.

The second issue is much simpler and works already with most VOs: they
simply redraw whatever has been uploaded previously. The exception is
vdpau, which has a complicated mechanism to track and filter video
frames. The state associated with this mechanism is completely cleared
with vo_seek_reset(), so implementing this to work as expected is not
trivial. For now, we just clear the window with black.

1 files changed, 11 insertions, 1 deletions

diff --git a/video/out/gl_video.c b/video/out/gl_video.c
index 21efc6dd56..3bab03c8aa 100644
--- a/video/out/gl_video.c
+++ b/video/out/gl_video.c
@@ -179,6 +179,7 @@ struct gl_video {
     int plane_count;
 
     struct video_image image;
+    bool have_image;
 
     struct fbotex indirect_fbo;         // RGB target
     struct fbotex scale_sep_fbo;        // first pass when doing 2 pass scaling
@@ -1353,6 +1354,11 @@ void gl_video_render_frame(struct gl_video *p)
         gl->Clear(GL_COLOR_BUFFER_BIT);
     }
 
+    if (!p->have_image) {
+        gl->Clear(GL_COLOR_BUFFER_BIT);
+        return;
+    }
+
     // Order of processing:
     //  [indirect -> [scale_sep ->]] final
 
@@ -1571,6 +1577,8 @@ void gl_video_upload_image(struct gl_video *p, struct mp_image *mpi)
     }
     gl->ActiveTexture(GL_TEXTURE0);
     gl->BindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+
+    p->have_image = true;
 }
 
 struct mp_image *gl_video_download_image(struct gl_video *p)
@@ -1579,7 +1587,7 @@ struct mp_image *gl_video_download_image(struct gl_video *p)
 
     struct video_image *vimg = &p->image;
 
-    if (!vimg->planes[0].gl_texture)
+    if (!p->have_image || !vimg->planes[0].gl_texture)
         return NULL;
 
     assert(p->image_format == p->image_params.imgfmt);
@@ -1991,6 +1999,8 @@ void gl_video_config(struct gl_video *p, struct mp_image_params *params)
     csp.levels_out = params->outputlevels;
     csp.format = params->colorspace;
     p->colorspace = csp;
+
+    p->have_image = false;
 }
 
 void gl_video_set_output_depth(struct gl_video *p, int r, int g, int b)