1 files changed, 159 insertions, 0 deletions
diff --git a/src/Ryujinx.Graphics.Nvdec.FFmpeg/H264/SpsAndPpsReconstruction.cs b/src/Ryujinx.Graphics.Nvdec.FFmpeg/H264/SpsAndPpsReconstruction.cs
new file mode 100644
index 00000000..57fb65d5
--- /dev/null
+++ b/src/Ryujinx.Graphics.Nvdec.FFmpeg/H264/SpsAndPpsReconstruction.cs
@@ -0,0 +1,159 @@
+using Ryujinx.Common.Memory;
+using Ryujinx.Graphics.Video;
+using System;
+
+namespace Ryujinx.Graphics.Nvdec.FFmpeg.H264
+{
+    static class SpsAndPpsReconstruction
+    {
+        public static Span<byte> Reconstruct(ref H264PictureInfo pictureInfo, byte[] workBuffer)
+        {
+            H264BitStreamWriter writer = new H264BitStreamWriter(workBuffer);
+
+            // Sequence Parameter Set.
+            writer.WriteU(1, 24);
+            writer.WriteU(0, 1);
+            writer.WriteU(3, 2);
+            writer.WriteU(7, 5);
+            writer.WriteU(100, 8); // Profile idc
+            writer.WriteU(0, 8); // Reserved
+            writer.WriteU(31, 8); // Level idc
+            writer.WriteUe(0); // Seq parameter set id
+            writer.WriteUe(pictureInfo.ChromaFormatIdc);
+
+            if (pictureInfo.ChromaFormatIdc == 3)
+            {
+                writer.WriteBit(false); // Separate colour plane flag
+            }
+
+            writer.WriteUe(0); // Bit depth luma minus 8
+            writer.WriteUe(0); // Bit depth chroma minus 8
+            writer.WriteBit(pictureInfo.QpprimeYZeroTransformBypassFlag);
+            writer.WriteBit(false); // Scaling matrix present flag
+
+            writer.WriteUe(pictureInfo.Log2MaxFrameNumMinus4);
+            writer.WriteUe(pictureInfo.PicOrderCntType);
+
+            if (pictureInfo.PicOrderCntType == 0)
+            {
+                writer.WriteUe(pictureInfo.Log2MaxPicOrderCntLsbMinus4);
+            }
+            else if (pictureInfo.PicOrderCntType == 1)
+            {
+                writer.WriteBit(pictureInfo.DeltaPicOrderAlwaysZeroFlag);
+
+                writer.WriteSe(0); // Offset for non-ref pic
+                writer.WriteSe(0); // Offset for top to bottom field
+                writer.WriteUe(0); // Num ref frames in pic order cnt cycle
+            }
+
+            writer.WriteUe(16); // Max num ref frames
+            writer.WriteBit(false); // Gaps in frame num value allowed flag
+            writer.WriteUe(pictureInfo.PicWidthInMbsMinus1);
+            writer.WriteUe(pictureInfo.PicHeightInMapUnitsMinus1);
+            writer.WriteBit(pictureInfo.FrameMbsOnlyFlag);
+
+            if (!pictureInfo.FrameMbsOnlyFlag)
+            {
+                writer.WriteBit(pictureInfo.MbAdaptiveFrameFieldFlag);
+            }
+
+            writer.WriteBit(pictureInfo.Direct8x8InferenceFlag);
+            writer.WriteBit(false); // Frame cropping flag
+            writer.WriteBit(false); // VUI parameter present flag
+
+            writer.End();
+
+            // Picture Parameter Set.
+            writer.WriteU(1, 24);
+            writer.WriteU(0, 1);
+            writer.WriteU(3, 2);
+            writer.WriteU(8, 5);
+
+            writer.WriteUe(0); // Pic parameter set id
+            writer.WriteUe(0); // Seq parameter set id
+
+            writer.WriteBit(pictureInfo.EntropyCodingModeFlag);
+            writer.WriteBit(pictureInfo.PicOrderPresentFlag);
+            writer.WriteUe(0); // Num slice groups minus 1
+            writer.WriteUe(pictureInfo.NumRefIdxL0ActiveMinus1);
+            writer.WriteUe(pictureInfo.NumRefIdxL1ActiveMinus1);
+            writer.WriteBit(pictureInfo.WeightedPredFlag);
+            writer.WriteU(pictureInfo.WeightedBipredIdc, 2);
+            writer.WriteSe(pictureInfo.PicInitQpMinus26);
+            writer.WriteSe(0); // Pic init qs minus 26
+            writer.WriteSe(pictureInfo.ChromaQpIndexOffset);
+            writer.WriteBit(pictureInfo.DeblockingFilterControlPresentFlag);
+            writer.WriteBit(pictureInfo.ConstrainedIntraPredFlag);
+            writer.WriteBit(pictureInfo.RedundantPicCntPresentFlag);
+            writer.WriteBit(pictureInfo.Transform8x8ModeFlag);
+
+            writer.WriteBit(pictureInfo.ScalingMatrixPresent);
+
+            if (pictureInfo.ScalingMatrixPresent)
+            {
+                for (int index = 0; index < 6; index++)
+                {
+                    writer.WriteBit(true);
+
+                    WriteScalingList(ref writer, pictureInfo.ScalingLists4x4[index]);
+                }
+
+                if (pictureInfo.Transform8x8ModeFlag)
+                {
+                    for (int index = 0; index < 2; index++)
+                    {
+                        writer.WriteBit(true);
+
+                        WriteScalingList(ref writer, pictureInfo.ScalingLists8x8[index]);
+                    }
+                }
+            }
+
+            writer.WriteSe(pictureInfo.SecondChromaQpIndexOffset);
+
+            writer.End();
+
+            return writer.AsSpan();
+        }
+
+        // ZigZag LUTs from libavcodec.
+        private static ReadOnlySpan<byte> ZigZagDirect => new byte[]
+        {
+            0,   1,  8, 16,  9,  2,  3, 10,
+            17, 24, 32, 25, 18, 11,  4,  5,
+            12, 19, 26, 33, 40, 48, 41, 34,
+            27, 20, 13,  6,  7, 14, 21, 28,
+            35, 42, 49, 56, 57, 50, 43, 36,
+            29, 22, 15, 23, 30, 37, 44, 51,
+            58, 59, 52, 45, 38, 31, 39, 46,
+            53, 60, 61, 54, 47, 55, 62, 63
+        };
+
+        private static ReadOnlySpan<byte> ZigZagScan => new byte[]
+        {
+            0 + 0 * 4, 1 + 0 * 4, 0 + 1 * 4, 0 + 2 * 4,
+            1 + 1 * 4, 2 + 0 * 4, 3 + 0 * 4, 2 + 1 * 4,
+            1 + 2 * 4, 0 + 3 * 4, 1 + 3 * 4, 2 + 2 * 4,
+            3 + 1 * 4, 3 + 2 * 4, 2 + 3 * 4, 3 + 3 * 4
+        };
+
+        private static void WriteScalingList(ref H264BitStreamWriter writer, IArray<byte> list)
+        {
+            ReadOnlySpan<byte> scan = list.Length == 16 ? ZigZagScan : ZigZagDirect;
+
+            int lastScale = 8;
+
+            for (int index = 0; index < list.Length; index++)
+            {
+                byte value = list[scan[index]];
+
+                int deltaScale = value - lastScale;
+
+                writer.WriteSe(deltaScale);
+
+                lastScale = value;
+            }
+        }
+    }
+}