vo_gpu: make screenshots use the GL renderer

Using the GL renderer for color conversion will make sure screenshots
will use the same conversion as normal video rendering. It can do this
for all types of screenshots.

The logic when to write 16 bit PNGs changes. To approximate the old
behavior, we decide by looking whether the source video format has more
than 8 bits per component. We apply this logic even for window
screenshots. Also, 16 bit PNGs now always include an unused alpha
channel. The reason is that FFmpeg has RGB48 and RGBA64 formats, but no
RGB064. RGB48 is 3 bytes and usually not supported by GPUs for
rendering, so we have to use RGBA64, which forces an alpha channel.

Will break for users who use --target-trc and similar options.

I considered creating a new gl_video context, but it could double GPU
memory use, so I didn't.

This uses FBOs instead of glGetTexImage(), because that increases the
chance it could work on GLES (e.g. ANGLE). Untested. No support for the
Vulkan and D3D11 backends yet.

Fixes #5498. Also fixes #5240, because the code for reading back is not
used with the new code path.

1 files changed, 11 insertions, 0 deletions

diff --git a/video/out/vo.h b/video/out/vo.h
index bf5995f722..4ce2cf1371 100644
--- a/video/out/vo.h
+++ b/video/out/vo.h
@@ -102,8 +102,13 @@ enum mp_voctrl {
     VOCTRL_GET_DISPLAY_NAMES,
 
     // Retrieve window contents. (Normal screenshots use vo_get_current_frame().)
+    // Deprecated for VOCTRL_SCREENSHOT with corresponding flags.
     VOCTRL_SCREENSHOT_WIN,              // struct mp_image**
 
+    // A normal screenshot - VOs can react to this if vo_get_current_frame() is
+    // not sufficient.
+    VOCTRL_SCREENSHOT,                  // struct voctrl_screenshot*
+
     VOCTRL_UPDATE_RENDER_OPTS,
 
     VOCTRL_GET_ICC_PROFILE,             // bstr*
@@ -170,6 +175,11 @@ struct voctrl_performance_data {
     struct mp_frame_perf fresh, redraw;
 };
 
+struct voctrl_screenshot {
+    bool scaled, subs, osd, high_bit_depth;
+    struct mp_image *res;
+};
+
 enum {
     // VO does handle mp_image_params.rotate in 90 degree steps
     VO_CAP_ROTATE90     = 1 << 0,
@@ -447,6 +457,7 @@ double vo_get_estimated_vsync_jitter(struct vo *vo);
 double vo_get_display_fps(struct vo *vo);
 double vo_get_delay(struct vo *vo);
 void vo_discard_timing_info(struct vo *vo);
+struct vo_frame *vo_get_current_vo_frame(struct vo *vo);
 struct mp_image *vo_get_image(struct vo *vo, int imgfmt, int w, int h,
                               int stride_align);