[Windows][GUI] Tonemap Kodi GUI to HDR PQ while in playback of HDR pass-through mode

Fixes very bright OSD, subtitles, etc. and wrong color space (oversaturated).

5 files changed, 36 insertions, 5 deletions

diff --git a/system/shaders/guishader_common.hlsl b/system/shaders/guishader_common.hlsl
index 0f2a7a7c47..1d8fa10e56 100644
--- a/system/shaders/guishader_common.hlsl
+++ b/system/shaders/guishader_common.hlsl
@@ -47,8 +47,39 @@ cbuffer cbWorld : register(b0)
   float4x4 worldViewProj;
   float blackLevel;
   float colorRange;
+  int PQ;
 };
 
+inline float3 transferPQ(float3 x)
+{
+  static const float ST2084_m1 = 2610.0f / (4096.0f * 4.0f);
+  static const float ST2084_m2 = (2523.0f / 4096.0f) * 128.0f;
+  static const float ST2084_c1 = 3424.0f / 4096.0f;
+  static const float ST2084_c2 = (2413.0f / 4096.0f) * 32.0f;
+  static const float ST2084_c3 = (2392.0f / 4096.0f) * 32.0f;
+  static const float SDR_peak_lum = 100.0f;
+  static const float3x3 matx =
+  {
+    0.627402, 0.329292, 0.043306,
+    0.069095, 0.919544, 0.011360,
+    0.016394, 0.088028, 0.895578
+  };
+  // REC.709 to linear
+  x = pow(x, 1.0f / 0.45f);
+  // REC.709 to BT.2020
+  x = mul(matx, x);
+  // linear to PQ
+  x = pow(x / SDR_peak_lum, ST2084_m1);
+  x = (ST2084_c1 + ST2084_c2 * x) / (1.0f + ST2084_c3 * x);
+  x = pow(x, ST2084_m2);
+  return x;
+}
+
+inline float4 tonemapHDR(float4 color)
+{
+  return (PQ) ? float4(transferPQ(color.rgb), color.a) : color;
+}
+
 inline float4 adjustColorRange(float4 color)
 {
   return float4(blackLevel + colorRange * color.rgb, color.a);
diff --git a/system/shaders/guishader_default.hlsl b/system/shaders/guishader_default.hlsl
index cf4183a0f9..82b6510c77 100644
--- a/system/shaders/guishader_default.hlsl
+++ b/system/shaders/guishader_default.hlsl
@@ -22,7 +22,7 @@
 
 float4 PS(PS_INPUT input) : SV_TARGET
 {
-  return adjustColorRange(input.color);
+  return tonemapHDR(adjustColorRange(input.color));
 }
 
 
diff --git a/system/shaders/guishader_fonts.hlsl b/system/shaders/guishader_fonts.hlsl
index def887d162..59c2ffec90 100644
--- a/system/shaders/guishader_fonts.hlsl
+++ b/system/shaders/guishader_fonts.hlsl
@@ -25,7 +25,7 @@ Texture2D texFont : register(t0);
 float4 PS(PS_INPUT input) : SV_TARGET
 {
   input.color.a *= texFont.Sample(LinearSampler, input.tex).r;
-  return adjustColorRange(input.color);
+  return tonemapHDR(adjustColorRange(input.color));
 }
 
 
diff --git a/system/shaders/guishader_multi_texture_blend.hlsl b/system/shaders/guishader_multi_texture_blend.hlsl
index 33f1f0fbd3..77c2e79255 100644
--- a/system/shaders/guishader_multi_texture_blend.hlsl
+++ b/system/shaders/guishader_multi_texture_blend.hlsl
@@ -24,8 +24,8 @@ Texture2D txDiffuse[2] : register(t0);
 
 float4 PS(PS_INPUT input) : SV_TARGET
 {
-  return adjustColorRange(input.color * txDiffuse[0].Sample(LinearSampler, input.tex)
-                          * txDiffuse[1].Sample(LinearSampler, input.tex2));
+  return tonemapHDR(adjustColorRange(input.color * txDiffuse[0].Sample(LinearSampler, input.tex) *
+                                     txDiffuse[1].Sample(LinearSampler, input.tex2)));
 }
 
 
diff --git a/system/shaders/guishader_texture.hlsl b/system/shaders/guishader_texture.hlsl
index 845747ec41..665aff0abb 100644
--- a/system/shaders/guishader_texture.hlsl
+++ b/system/shaders/guishader_texture.hlsl
@@ -24,7 +24,7 @@ Texture2D texMain : register(t0);
 
 float4 PS(PS_INPUT input) : SV_TARGET
 {
-  return adjustColorRange(input.color * texMain.Sample(LinearSampler, input.tex));
+  return tonemapHDR(adjustColorRange(input.color * texMain.Sample(LinearSampler, input.tex)));
 }