From 50223dbdb89a95139201d6fdf8b7efb88a35c3cd Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Sat, 1 Nov 2025 18:45:02 -0500
Subject: [PATCH] Fix accuracy issues in YUV to RGB conversion of 10-bit
 content in D3D11VA

See #1667 for details.
---
 app/shaders/d3d11_bt2020lim_pixel.fxc         | Bin 1548 -> 1548 bytes
 app/shaders/d3d11_bt2020lim_pixel.hlsl        |   8 +--
 .../video/ffmpeg-renderers/d3d11va.cpp        |  57 ++++++++----------
 3 files changed, 29 insertions(+), 36 deletions(-)

diff --git a/app/shaders/d3d11_bt2020lim_pixel.fxc b/app/shaders/d3d11_bt2020lim_pixel.fxc
index b015bbebb85ddb1f9bc696672ee1558510da44ad..9a57d143cdf17a15d3bb7b449d55426232ce5e5b 100644
GIT binary patch
delta 166
zcmeC->ERJ^iEwh>9vWRNnZofWS9#S>gURnBCW@5!aVRwG<xpVQ&%n@N&j1903=FJH
z4Ezf!s;1hTG+YOZ!Ni%N;&(C}_HAHR2kL>SXMu`WRBgQWiIEFtB!|M}OH69)P?IMA
aXVT;bv7x#r8#Al2f%p|wo8y?*F#!Mot}|!=

delta 166
zcmeC->ERJ^iEwhh^zUm(;pRK$t7h;hSOuGeP82EeYiwxP+t|RcpMjylo&g8~85mfZ
z82A_Pb5FJZefk<$3?|MD6+ijZexG)`8c+{JJquLaL3rb}PmEkJBO4ngUt&^Yhnh6`
aKa(amhz->}*_c_C4a9d4-W<ogjtKx0$~1!j

diff --git a/app/shaders/d3d11_bt2020lim_pixel.hlsl b/app/shaders/d3d11_bt2020lim_pixel.hlsl
index e4e7bc40..bb9f3100 100644
--- a/app/shaders/d3d11_bt2020lim_pixel.hlsl
+++ b/app/shaders/d3d11_bt2020lim_pixel.hlsl
@@ -2,14 +2,14 @@
 
 static const min16float3x3 cscMatrix =
 {
-    1.1644, 1.1644, 1.1644,
-    0.0, -0.1874, 2.1418,
-    1.6781, -0.6505, 0.0,
+    1.1678, 1.1678, 1.1678,
+    0.0, -0.1879, 2.1481,
+    1.6836, -0.6524, 0.0,
 };
 
 static const min16float3 offsets =
 {
-    16.0 / 255.0, 128.0 / 255.0, 128.0 / 255.0
+    64.0 / 1023.0, 512.0 / 1023.0, 512.0 / 1023.0
 };
 
 #include "d3d11_video_pixel_end.hlsli"
\ No newline at end of file
diff --git a/app/streaming/video/ffmpeg-renderers/d3d11va.cpp b/app/streaming/video/ffmpeg-renderers/d3d11va.cpp
index 9bfffa18..212a1bf7 100644
--- a/app/streaming/video/ffmpeg-renderers/d3d11va.cpp
+++ b/app/streaming/video/ffmpeg-renderers/d3d11va.cpp
@@ -28,32 +28,17 @@ typedef struct _VERTEX
 #define CSC_MATRIX_RAW_ELEMENT_COUNT 9
 #define CSC_MATRIX_PACKED_ELEMENT_COUNT 12
 
-static const float k_CscMatrix_Bt601Lim[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
-    1.1644f, 1.1644f, 1.1644f,
-    0.0f, -0.3917f, 2.0172f,
-    1.5960f, -0.8129f, 0.0f,
-};
-static const float k_CscMatrix_Bt601Full[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
+static const float k_CscMatrix_Bt601[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
     1.0f, 1.0f, 1.0f,
     0.0f, -0.3441f, 1.7720f,
     1.4020f, -0.7141f, 0.0f,
 };
-static const float k_CscMatrix_Bt709Lim[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
-    1.1644f, 1.1644f, 1.1644f,
-    0.0f, -0.2132f, 2.1124f,
-    1.7927f, -0.5329f, 0.0f,
-};
-static const float k_CscMatrix_Bt709Full[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
+static const float k_CscMatrix_Bt709[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
     1.0f, 1.0f, 1.0f,
     0.0f, -0.1873f, 1.8556f,
     1.5748f, -0.4681f, 0.0f,
 };
-static const float k_CscMatrix_Bt2020Lim[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
-    1.1644f, 1.1644f, 1.1644f,
-    0.0f, -0.1874f, 2.1418f,
-    1.6781f, -0.6505f, 0.0f,
-};
-static const float k_CscMatrix_Bt2020Full[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
+static const float k_CscMatrix_Bt2020[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
     1.0f, 1.0f, 1.0f,
     0.0f, -0.1646f, 1.8814f,
     1.4746f, -0.5714f, 0.0f,
@@ -61,15 +46,12 @@ static const float k_CscMatrix_Bt2020Full[CSC_MATRIX_RAW_ELEMENT_COUNT] = {
 
 #define OFFSETS_ELEMENT_COUNT 3
 
-static const float k_Offsets_Lim[OFFSETS_ELEMENT_COUNT] = { 16.0f / 255.0f, 128.0f / 255.0f, 128.0f / 255.0f };
-static const float k_Offsets_Full[OFFSETS_ELEMENT_COUNT] = { 0.0f, 128.0f / 255.0f, 128.0f / 255.0f };
-
 typedef struct _CSC_CONST_BUF
 {
-    // CscMatrix value from above but packed appropriately
+    // CscMatrix value from above but packed and scaled
     float cscMatrix[CSC_MATRIX_PACKED_ELEMENT_COUNT];
 
-    // YUV offset values from above
+    // YUV offset values
     float offsets[OFFSETS_ELEMENT_COUNT];
 
     // Padding float to be a multiple of 16 bytes
@@ -721,6 +703,7 @@ void D3D11VARenderer::bindColorConversion(AVFrame* frame)
     bool fullRange = isFrameFullRange(frame);
     int colorspace = getFrameColorspace(frame);
     bool yuv444 = (m_DecoderParams.videoFormat & VIDEO_FORMAT_MASK_YUV444);
+    int bits = (colorspace == COLORSPACE_REC_2020) ? 10 : 8;
 
     // We have purpose-built shaders for the common Rec 601 (SDR) and Rec 2020 (HDR) YUV 4:2:0 cases
     if (!yuv444 && !fullRange && colorspace == COLORSPACE_REC_601) {
@@ -772,33 +755,43 @@ void D3D11VARenderer::bindColorConversion(AVFrame* frame)
         const float* rawCscMatrix;
         switch (colorspace) {
         case COLORSPACE_REC_601:
-            rawCscMatrix = fullRange ? k_CscMatrix_Bt601Full : k_CscMatrix_Bt601Lim;
+            rawCscMatrix = k_CscMatrix_Bt601;
             break;
         case COLORSPACE_REC_709:
-            rawCscMatrix = fullRange ? k_CscMatrix_Bt709Full : k_CscMatrix_Bt709Lim;
+            rawCscMatrix = k_CscMatrix_Bt709;
             break;
         case COLORSPACE_REC_2020:
-            rawCscMatrix = fullRange ? k_CscMatrix_Bt2020Full : k_CscMatrix_Bt2020Lim;
+            rawCscMatrix = k_CscMatrix_Bt2020;
             break;
         default:
             SDL_assert(false);
             return;
         }
 
+        int range = (1 << bits);
+        double yMin = (fullRange ? 0 : (16 << (bits - 8)));
+        double yMax = (fullRange ? (range - 1) : (235 << (bits - 8)));
+        double yScale = (range - 1) / (yMax - yMin);
+        double uvMin = (fullRange ? 0 : (16 << (bits - 8)));
+        double uvMax = (fullRange ? (range - 1) : (240 << (bits - 8)));
+        double uvScale = (range - 1) / (uvMax - uvMin);
+
+        // Calculate YUV offsets
+        constBuf.offsets[0] = yMin / (double)(range - 1);
+        constBuf.offsets[1] = (range / 2) / (double)(range - 1);
+        constBuf.offsets[2] = (range / 2) / (double)(range - 1);
+
         // We need to adjust our raw CSC matrix to be column-major and with float3 vectors
         // padded with a float in between each of them to adhere to HLSL requirements.
         for (int i = 0; i < 3; i++) {
             for (int j = 0; j < 3; j++) {
                 constBuf.cscMatrix[i * 4 + j] = rawCscMatrix[j * 3 + i];
+
+                // Scale the color matrix according to the color range
+                constBuf.cscMatrix[i * 4 + j] *= (j == 0) ? yScale : uvScale;
             }
         }
 
-        // No adjustments are needed to the float[3] array of offsets, so it can just
-        // be copied with memcpy().
-        memcpy(constBuf.offsets,
-               fullRange ? k_Offsets_Full : k_Offsets_Lim,
-               sizeof(constBuf.offsets));
-
         D3D11_SUBRESOURCE_DATA constData = {};
         constData.pSysMem = &constBuf;