vo_opengl: generalize HDR tone mapping mechanism

This involves multiple changes:

1. Brightness metadata is split into nominal peak and signal peak.

For a quick and dirty explanation: nominal peak is the brightest value
that your color space can represent (i.e. the brightness of an encoded
1.0), and signal peak is the brightest value that actually occurs in
the video (i.e. the brightest thing that's displayed).

2. vo_opengl uses a new decision logic to figure out the right nom_peak
and sig_peak for all situations. It also does a better job of picking
the right target gamut/colorspace to use for the OSD. (Which still is
and still should be treated as sRGB). This change in logic also
fixes #3293 en passant.

3. Since it was growing rapidly, the logic for auto-guessing / inferring
the right colorimetry configuration (in pass_colormanage) was split from
the logic for actually performing the adaptation (now pass_color_map).

Right now, the new logic doesn't do a whole lot since HDR metadata is
still ignored (but not for long).

1 files changed, 3 insertions, 0 deletions

diff --git a/video/decode/lavc.h b/video/decode/lavc.h
index 689222d872..e76dff50bc 100644
--- a/video/decode/lavc.h
+++ b/video/decode/lavc.h
@@ -25,6 +25,9 @@ typedef struct lavc_ctx {
     bool hwdec_failed;
     bool hwdec_notified;
 
+    // For HDR side-data caching
+    int cached_hdr_peak;
+
     struct mp_image **delay_queue;
     int num_delay_queue;
     int max_delay_queue;