From f79eeadde62ea6517181218c470c65ffe8c6be86 Mon Sep 17 00:00:00 2001
From: Johanness <mrjitten@protonmail.com>
Date: Sun, 24 May 2026 21:17:44 +0300
Subject: [PATCH] Document BT.709 v210 conversion

---
 PixelFormat.hpp          | 6 +++++-
 shaders/v210_decode.comp | 4 +++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/PixelFormat.hpp b/PixelFormat.hpp
index 74dce4e..f29a210 100644
--- a/PixelFormat.hpp
+++ b/PixelFormat.hpp
@@ -95,6 +95,8 @@ inline void decodeV210Line(
             default: y10 = y0; cb10 = cb0; cr10 = cr0; break;
         }
 
+        // BT.709 limited-range YCbCr to RGB. v210 stores 10-bit video-range
+        // samples: Y [64, 940], Cb/Cr centered at 512.
         int32_t yp  = (static_cast<int32_t>(y10) - 64) >> 2;
         int32_t cbp = (static_cast<int32_t>(cb10) - 512) >> 2;
         int32_t crp = (static_cast<int32_t>(cr10) - 512) >> 2;
@@ -175,6 +177,8 @@ inline void convertV210ToRgba(
                 default: y10 = y0; cb10 = cb0; cr10 = cr0; break;
             }
 
+            // BT.709 limited-range YCbCr to RGB. v210 stores 10-bit video-range
+            // samples: Y [64, 940], Cb/Cr centered at 512.
             int32_t yp  = (static_cast<int32_t>(y10) - 64) >> 2;
             int32_t cbp = (static_cast<int32_t>(cb10) - 512) >> 2;
             int32_t crp = (static_cast<int32_t>(cr10) - 512) >> 2;
@@ -187,4 +191,4 @@ inline void convertV210ToRgba(
                 {clampUint8(r), clampUint8(g), clampUint8(b)});
         }
     }
-}
\ No newline at end of file
+}
diff --git a/shaders/v210_decode.comp b/shaders/v210_decode.comp
index f4e2033..66d8a73 100644
--- a/shaders/v210_decode.comp
+++ b/shaders/v210_decode.comp
@@ -62,6 +62,8 @@ void main()
         default: y10 = y5;  cb10 = cb4; cr10 = cr4; break;
     }
 
+    // BT.709 limited-range YCbCr to RGB. v210 stores 10-bit video-range
+    // samples: Y [64, 940], Cb/Cr centered at 512.
     int yp  = int(y10) - 64;
     int cbp = int(cb10) - 512;
     int crp = int(cr10) - 512;
@@ -79,4 +81,4 @@ void main()
     b = clamp(b, 0, 255);
 
     imageStore(dstImage, dstPos, vec4(float(r) / 255.0, float(g) / 255.0, float(b) / 255.0, 1.0));
-}
\ No newline at end of file
+}