NVDEC implementation using FFmpeg (#443)

* Initial nvdec implementation using FFmpeg

* Fix swapped channels on the video decoder and the G8R8 texture format

* Fix texture samplers not being set properly (regression)

* Rebased

* Remove unused code introduced on the rebase

* Add support for RGBA8 output format on the video image composer

* Correct spacing

* Some fixes for rebase and other tweaks

* Allow size mismatch on frame copy

* Get rid of GetHostAddress calls on VDec

1 files changed, 134 insertions, 0 deletions

diff --git a/Ryujinx.Graphics/VDec/VpxRangeEncoder.cs b/Ryujinx.Graphics/VDec/VpxRangeEncoder.cs
new file mode 100644
index 00000000..3e381d2c
--- /dev/null
+++ b/Ryujinx.Graphics/VDec/VpxRangeEncoder.cs
@@ -0,0 +1,134 @@
+using System.IO;
+
+namespace Ryujinx.Graphics.VDec
+{
+    class VpxRangeEncoder
+    {
+        private const int HalfProbability = 128;
+
+        private static readonly int[] NormLut = new int[]
+        {
+            0, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
+            3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+            2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+            0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+        };
+
+        private Stream BaseStream;
+
+        private uint LowValue;
+        private uint Range;
+        private int  Count;
+
+        public VpxRangeEncoder(Stream BaseStream)
+        {
+            this.BaseStream = BaseStream;
+
+            Range = 0xff;
+            Count = -24;
+
+            Write(false);
+        }
+
+        public void WriteByte(byte Value)
+        {
+            Write(Value, 8);
+        }
+
+        public void Write(int Value, int ValueSize)
+        {
+            for (int Bit = ValueSize - 1; Bit >= 0; Bit--)
+            {
+                Write(((Value >> Bit) & 1) != 0);
+            }
+        }
+
+        public void Write(bool Bit)
+        {
+            Write(Bit, HalfProbability);
+        }
+
+        public void Write(bool Bit, int Probability)
+        {
+            uint Range = this.Range;
+
+            uint Split = 1 + (((Range - 1) * (uint)Probability) >> 8);
+
+            Range = Split;
+
+            if (Bit)
+            {
+                LowValue += Split;
+                Range     = this.Range - Split;
+            }
+
+            int Shift = NormLut[Range];
+
+            Range <<= Shift;
+            Count +=  Shift;
+
+            if (Count >= 0)
+            {
+                int Offset = Shift - Count;
+
+                if (((LowValue << (Offset - 1)) >> 31) != 0)
+                {
+                    long CurrentPos = BaseStream.Position;
+
+                    BaseStream.Seek(-1, SeekOrigin.Current);
+
+                    while (BaseStream.Position >= 0 && PeekByte() == 0xff)
+                    {
+                        BaseStream.WriteByte(0);
+
+                        BaseStream.Seek(-2, SeekOrigin.Current);
+                    }
+
+                    BaseStream.WriteByte((byte)(PeekByte() + 1));
+
+                    BaseStream.Seek(CurrentPos, SeekOrigin.Begin);
+                }
+
+                BaseStream.WriteByte((byte)(LowValue >> (24 - Offset)));
+
+                LowValue <<= Offset;
+                Shift      = Count;
+                LowValue  &= 0xffffff;
+                Count     -= 8;
+            }
+
+            LowValue <<= Shift;
+
+            this.Range = Range;
+        }
+
+        private byte PeekByte()
+        {
+            byte Value = (byte)BaseStream.ReadByte();
+
+            BaseStream.Seek(-1, SeekOrigin.Current);
+
+            return Value;
+        }
+
+        public void End()
+        {
+            for (int Index = 0; Index < 32; Index++)
+            {
+                Write(false);
+            }
+        }
+    }
+}
\ No newline at end of file