video: refactor HDR implementation

List of changes:

1. Kill nom_peak, since it's a pointless non-field that stores nothing
   of value and is _always_ derived from ref_white anyway.

2. Kill ref_white/--target-brightness, because the only case it really
   existed for (PQ) actually doesn't need to be this general: According
   to ITU-R BT.2100, PQ *always* assumes a reference monitor with a
   white point of 100 cd/m².

3. Improve documentation and comments surrounding this stuff.
4. Clean up some of the code in general. Move stuff where it belongs.

1 files changed, 1 insertions, 1 deletions

diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c
index c3988b8bf8..da50b1ee0f 100644
--- a/demux/demux_mkv.c
+++ b/demux/demux_mkv.c
@@ -572,7 +572,7 @@ static void parse_trackcolour(struct demuxer *demuxer, struct mkv_track *track,
         struct ebml_mastering_metadata *mastering = &colour->mastering_metadata;
 
         if (mastering->n_luminance_max) {
-            track->color.sig_peak = mastering->luminance_max;
+            track->color.sig_peak = mastering->luminance_max / MP_REF_WHITE;
             MP_VERBOSE(demuxer, "|    + HDR peak: %f\n", track->color.sig_peak);
         }
     }