1  using Ryujinx.Graphics.Nvdec.FFmpeg.Native;
 2  using Ryujinx.Graphics.Video;
 3  using System;
 4  
 5  namespace Ryujinx.Graphics.Nvdec.FFmpeg.Vp8
 6  {
 7      public sealed class Decoder : IDecoder
 8      {
 9          public bool IsHardwareAccelerated => false;
10  
11          private readonly FFmpegContext _context = new(AVCodecID.AV_CODEC_ID_VP8);
12  
13          public ISurface CreateSurface(int width, int height)
14          {
15              return new Surface(width, height);
16          }
17  
18          public bool Decode(ref Vp8PictureInfo pictureInfo, ISurface output, ReadOnlySpan<byte> bitstream)
19          {
20              Surface outSurf = (Surface)output;
21  
22              int uncompHeaderSize = pictureInfo.KeyFrame ? 10 : 3;
23  
24              byte[] frame = new byte[bitstream.Length + uncompHeaderSize];
25  
26              uint firstPartSizeShifted = pictureInfo.FirstPartSize << 5;
27  
28              frame[0] = (byte)(pictureInfo.KeyFrame ? 0 : 1);
29              frame[0] |= (byte)((pictureInfo.Version & 7) << 1);
30              frame[0] |= 1 << 4;
31              frame[0] |= (byte)firstPartSizeShifted;
32              frame[1] |= (byte)(firstPartSizeShifted >> 8);
33              frame[2] |= (byte)(firstPartSizeShifted >> 16);
34  
35              if (pictureInfo.KeyFrame)
36              {
37                  frame[3] = 0x9d;
38                  frame[4] = 0x01;
39                  frame[5] = 0x2a;
40                  frame[6] = (byte)pictureInfo.FrameWidth;
41                  frame[7] = (byte)((pictureInfo.FrameWidth >> 8) & 0x3F);
42                  frame[8] = (byte)pictureInfo.FrameHeight;
43                  frame[9] = (byte)((pictureInfo.FrameHeight >> 8) & 0x3F);
44              }
45  
46              bitstream.CopyTo(new Span<byte>(frame)[uncompHeaderSize..]);
47  
48              return _context.DecodeFrame(outSurf, frame) == 0;
49          }
50  
51          public void Dispose() => _context.Dispose();
52      }
53  }