Fixed BT2020 decode speed.

ggarra13 · Mar 11, 2024 · fc333c6 · fc333c6
1 parent 1f99f57
commit fc333c6
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Showing 2 changed files with 24 additions and 19 deletions.
diff --git a/lib/tlCore/Image.cpp b/lib/tlCore/Image.cpp
@@ -93,10 +93,9 @@ namespace tl
             const std::array<math::Vector4f, static_cast<size_t>(YUVCoefficients::Count)> data =
             {
                 math::Vector4f(1.79274, 2.1124, 0.213242, 0.532913),
-                // Is BT2020 right?  These are the coeffs I got:
-                // math::Vector4f(1.4746, 2.0184, 1.5958, 0.0);  // chatgpt3.5
-                // math::Vector4f(1.8556, 2.14101, 0.2124, 0.6301), // gemini
-                math::Vector4f(1.67867, 2.14177, 0.187332, 0.650421) // darby
+                // Is Darby's BT2020 right?  These are the coeffs I got:
+                math::Vector4f(1.8556, 2.14101, 0.2124, 0.6301), // gemini
+                //math::Vector4f(1.67867, 2.14177, 0.187332, 0.650421) // darby
             };
             return data[static_cast<size_t>(value)];
         }

diff --git a/lib/tlIO/FFmpegReadVideo.cpp b/lib/tlIO/FFmpegReadVideo.cpp
@@ -606,25 +606,31 @@ namespace tl
                     {
                         throw std::runtime_error(string::Format("{0}: Cannot initialize sws context").arg(_fileName));
                     }
-                    
+
                     const auto params = _avCodecParameters[_avStream];
-                    int in_full, out_full, brightness, contrast, saturation;
-                    const int *inv_table, *table;
 
-                    sws_getColorspaceDetails(
-                        _swsContext, (int**)&inv_table, &in_full,
-                        (int**)&table, &out_full, &brightness, &contrast,
-                        &saturation);
-
-                    inv_table = sws_getCoefficients(params->color_space);
-                    table = sws_getCoefficients(AVCOL_SPC_BT709);
+                    // We should not do a BT2020_NCL to BT709 conversion in
+                    // software which is slow.
+                    if (params->color_space != AVCOL_SPC_BT2020_NCL)
+                    {
+                        int in_full, out_full, brightness, contrast, saturation;
+                        const int *inv_table, *table;
+
+                        sws_getColorspaceDetails(
+                            _swsContext, (int**)&inv_table, &in_full,
+                            (int**)&table, &out_full, &brightness, &contrast,
+                            &saturation);
+
+                        inv_table = sws_getCoefficients(params->color_space);
+                        table = sws_getCoefficients(AVCOL_SPC_BT709);
 
-                    in_full = (params->color_range == AVCOL_RANGE_JPEG);
-                    out_full = (params->color_range == AVCOL_RANGE_JPEG);
+                        in_full = (params->color_range == AVCOL_RANGE_JPEG);
+                        out_full = (params->color_range == AVCOL_RANGE_JPEG);
 
-                    sws_setColorspaceDetails(
-                        _swsContext, inv_table, in_full, table, out_full,
-                        brightness, contrast, saturation);
+                        sws_setColorspaceDetails(
+                            _swsContext, inv_table, in_full, table, out_full,
+                            brightness, contrast, saturation);
+                    }
                 }
             }
         }