Fix Output Color Tags And CPU Conversion Matrix

Util/FFmpeg/FFmpegNativeEncoder.cs

@@ -201,6 +201,12 @@ namespace ADOFAIRenderer.Util.FFmpeg
         /// </summary>
         private AVPixelFormat _dstPixFmt = AVPixelFormat.AV_PIX_FMT_YUV420P;
 
+        /// <summary>
+        /// Color range of the encoder input and output (codec context color_range of the selected encoder).
+        /// Full range (JPEG) for every encoder except libvvenc, limited range (MPEG) for libvvenc.
+        /// </summary>
+        private AVColorRange _colorRange = AVColorRange.AVCOL_RANGE_JPEG;
+
         /// <summary>Pixel format of the finally selected and running encoder.</summary>
         public AVPixelFormat SelectedPixelFormat => _dstPixFmt;
 
@@ -399,7 +405,19 @@ namespace ADOFAIRenderer.Util.FFmpeg
                         // ── Basic video parameters configuration ──
                         _pCodecContext->width = _settings.Width;
                         _pCodecContext->height = _settings.Height;
-                        _pCodecContext->color_range = AVColorRange.AVCOL_RANGE_JPEG;
+
+                        // ── Output color tags ──
+                        // Matrix: BT.709, the RGB→YUV matrix of both conversion paths
+                        //   (GPU: RGB2YUV_BT709_Full in ColorConversion.compute, CPU: ConfigureSwsColorspace).
+                        //   Players use this tag to convert the YUV frames back to RGB.
+                        // Range: full (0-255) for every encoder except libvvenc, limited (16-235) for libvvenc.
+                        //   The FFmpeg libvvenc wrapper passes the matrix/primaries/transfer tags to VVenC but not the range,
+                        //   so a VVC stream is read as limited range; its input is converted to limited range to match.
+                        // Reference: https://github.com/FFmpeg/FFmpeg/blob/release/8.0/libavcodec/libvvenc.c (vvenc_set_color_format)
+                        _pCodecContext->color_range = encoder == VideoEncoder.LibVvenc
+                            ? AVColorRange.AVCOL_RANGE_MPEG
+                            : AVColorRange.AVCOL_RANGE_JPEG;
+                        _pCodecContext->colorspace = AVColorSpace.AVCOL_SPC_BT709;
                         // thread_count = 0: FFmpeg automatically allocates threads according to the system CPU core count.
                         // For libvvenc, the FFmpeg wrapper passes thread_count as the VVenC internal thread count,
                         // so setting 0 (auto) is required for parallel encoding utilizing all cores.
@@ -756,6 +774,7 @@ namespace ADOFAIRenderer.Util.FFmpeg
                             var accelStatus = isHardware ? "Hardware Acceleration Enabled" : "Software CPU Usage";
                             Melon<RenderMod>.Logger.Msg($"Video encoder successfully initialized: {encoder.Name} ({accelStatus})");
                             _dstPixFmt = selectedPixFmt;
+                            _colorRange = _pCodecContext->color_range;
                             openedSuccessfully = true;
                             break;
                         }
@@ -855,6 +874,8 @@ namespace ADOFAIRenderer.Util.FFmpeg
                     if (_pSwsContext == null)
                         throw new Exception("Failed to initialize software scaler.");
 
+                    ConfigureSwsColorspace();
+
                     _isInitialized = true;
                     _loggedConversionMode = false;
                 }
@@ -1240,7 +1261,51 @@ namespace ADOFAIRenderer.Util.FFmpeg
         }
 
         /// <summary>
-        /// Sets the format, size and color range of the destination frame (_pDstFrame) and allocates a new pixel buffer for it.
+        /// Sets the RGB→YUV conversion of the CPU conversion path (_pSwsContext) to the BT.709 matrix
+        /// and the color range of the encoder (_colorRange), so that it produces the same colors as the GPU path
+        /// (RGB2YUV_BT709_Full in ColorConversion.compute) and as the tags of the output stream.
+        /// A new libswscale context uses the BT.601 matrix (SWS_CS_DEFAULT = SWS_CS_ITU601) and the limited range.
+        ///
+        /// For RGB input, "table" holds the coefficients of the output YUV space and dstRange its range (1 = full, 0 = limited).
+        /// The source (RGB) values, brightness, contrast and saturation keep the values of the context.
+        ///
+        /// Reference: https://ffmpeg.org/doxygen/trunk/group__libsws.html (sws_setColorspaceDetails, sws_getCoefficients)
+        /// Reference: https://github.com/FFmpeg/FFmpeg/blob/release/8.0/libswscale/swscale.h (SWS_CS_ITU709, SWS_CS_DEFAULT)
+        /// </summary>
+        private void ConfigureSwsColorspace()
+        {
+            int* currentInvTable;
+            int* currentTable;
+            int srcRange, dstRange, brightness, contrast, saturation;
+
+            var ret = ffmpeg.sws_getColorspaceDetails(_pSwsContext, &currentInvTable, &srcRange, &currentTable, &dstRange,
+                &brightness, &contrast, &saturation);
+            if (ret < 0)
+            {
+                Melon<RenderMod>.Logger.Warning($"[Encoder] Cannot read the colorspace details of the software scaler: {GetFFmpegErrorString(ret)} (Code: {ret}). The CPU conversion path keeps the libswscale defaults.");
+                return;
+            }
+
+            var coefficients = ffmpeg.sws_getCoefficients(ffmpeg.SWS_CS_ITU709);
+            var invTable = new int_array4();
+            var table = new int_array4();
+            for (uint i = 0; i < 4; i++)
+            {
+                invTable[i] = currentInvTable[i];
+                table[i] = coefficients[i];
+            }
+
+            var fullRange = _colorRange == AVColorRange.AVCOL_RANGE_JPEG;
+            ret = ffmpeg.sws_setColorspaceDetails(_pSwsContext, invTable, srcRange, table, fullRange ? 1 : 0,
+                brightness, contrast, saturation);
+            if (ret < 0)
+            {
+                Melon<RenderMod>.Logger.Warning($"[Encoder] Cannot set the colorspace details of the software scaler: {GetFFmpegErrorString(ret)} (Code: {ret}). The CPU conversion path keeps the libswscale defaults.");
+            }
+        }
+
+        /// <summary>
+        /// Sets the format, size, color range and matrix of the destination frame (_pDstFrame) and allocates a new pixel buffer for it.
         /// av_frame_get_buffer allocates memory matching format, width and height and sets the data[]/linesize[] pointers.
         /// Second argument 0 means default alignment.
         /// Reference: https://ffmpeg.org/doxygen/trunk/group__lavu__frame.html (av_frame_get_buffer)
@@ -1250,7 +1315,8 @@ namespace ADOFAIRenderer.Util.FFmpeg
             _pDstFrame->format = (int)_dstPixFmt;
             _pDstFrame->width = _settings.Width;
             _pDstFrame->height = _settings.Height;
-            _pDstFrame->color_range = AVColorRange.AVCOL_RANGE_JPEG;
+            _pDstFrame->color_range = _colorRange;
+            _pDstFrame->colorspace = AVColorSpace.AVCOL_SPC_BT709;
 
             var ret = ffmpeg.av_frame_get_buffer(_pDstFrame, 0);
             if (ret < 0)