From 3f1bc25d4de6150b0acff7e92d3e3084a7d989f0 Mon Sep 17 00:00:00 2001
From: Niklas Haas <git@haasn.xyz>
Date: Fri, 4 Jan 2019 16:46:38 +0100
Subject: vo_gpu: use dB units for scene change detection

Rather than the linear cd/m^2 units, these (relative) logarithmic units
lend themselves much better to actually detecting scene changes,
especially since the scene averaging was changed to also work
logarithmically.
---
 video/out/gpu/video.c         | 12 ++++++------
 video/out/gpu/video.h         |  4 ++--
 video/out/gpu/video_shaders.c |  7 ++++---
 3 files changed, 12 insertions(+), 11 deletions(-)

(limited to 'video')

diff --git a/video/out/gpu/video.c b/video/out/gpu/video.c
index df357b3552..24e6990139 100644
--- a/video/out/gpu/video.c
+++ b/video/out/gpu/video.c
@@ -318,8 +318,8 @@ static const struct gl_video_opts gl_video_opts_def = {
         .curve_param = NAN,
         .max_boost = 1.0,
         .decay_rate = 100.0,
-        .scene_threshold_low = 50,
-        .scene_threshold_high = 200,
+        .scene_threshold_low = 5.5,
+        .scene_threshold_high = 10.0,
         .desat = 0.75,
         .desat_exp = 1.5,
     },
@@ -372,10 +372,10 @@ const struct m_sub_options gl_video_conf = {
                     {"yes", 1},
                     {"no", -1})),
         OPT_FLOATRANGE("hdr-peak-decay-rate", tone_map.decay_rate, 0, 1.0, 1000.0),
-        OPT_INTRANGE("hdr-scene-threshold-low",
-                     tone_map.scene_threshold_low, 0, 0, 10000),
-        OPT_INTRANGE("hdr-scene-threshold-high",
-                     tone_map.scene_threshold_high, 0, 0, 10000),
+        OPT_FLOATRANGE("hdr-scene-threshold-low",
+                       tone_map.scene_threshold_low, 0, 0, 20.0),
+        OPT_FLOATRANGE("hdr-scene-threshold-high",
+                       tone_map.scene_threshold_high, 0, 0, 20.0),
         OPT_FLOAT("tone-mapping-param", tone_map.curve_param, 0),
         OPT_FLOATRANGE("tone-mapping-max-boost", tone_map.max_boost, 0, 1.0, 10.0),
         OPT_FLOAT("tone-mapping-desaturate", tone_map.desat, 0),
diff --git a/video/out/gpu/video.h b/video/out/gpu/video.h
index 0bd5c57e8f..1b0994ac78 100644
--- a/video/out/gpu/video.h
+++ b/video/out/gpu/video.h
@@ -101,8 +101,8 @@ struct gl_tone_map_opts {
     float max_boost;
     int compute_peak;
     float decay_rate;
-    int scene_threshold_low;
-    int scene_threshold_high;
+    float scene_threshold_low;
+    float scene_threshold_high;
     float desat;
     float desat_exp;
     int gamut_warning; // bool
diff --git a/video/out/gpu/video_shaders.c b/video/out/gpu/video_shaders.c
index 07ac0b940f..5fea739385 100644
--- a/video/out/gpu/video_shaders.c
+++ b/video/out/gpu/video_shaders.c
@@ -613,9 +613,10 @@ static void hdr_update_peak(struct gl_shader_cache *sc,
     GLSLF("  average += %f * (cur - average);\n", decay);
 
     // Scene change hysteresis
-    GLSLF("  float weight = smoothstep(%f, %f, abs(cur.x - average.x));\n",
-          (float) opts->scene_threshold_low / MP_REF_WHITE,
-          (float) opts->scene_threshold_high / MP_REF_WHITE);
+    float log_db = 10.0 / log(10.0);
+    GLSLF("  float weight = smoothstep(%f, %f, abs(log(cur.x / average.x)));\n",
+          opts->scene_threshold_low / log_db,
+          opts->scene_threshold_high / log_db);
     GLSL(    average = mix(average, cur, weight);)
 
     // Reset SSBO state for the next frame
-- 
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