YUYV422.hpp

#pragma once
#include <Gfx/Graph/decoders/ColorSpace.hpp>
#include <Gfx/Graph/decoders/GPUVideoDecoder.hpp>
extern "C" {
#include <libavformat/avformat.h>
}
 
namespace score::gfx
{
struct YUYV422Decoder : GPUVideoDecoder
{
  static const constexpr auto frag = R"_(#version 450
 
)_" SCORE_GFX_VIDEO_UNIFORMS R"_(
 
layout(binding=3) uniform sampler2D u_tex;
 
layout(location = 0) in vec2 v_texcoord;
layout(location = 0) out vec4 fragColor;
 
%2
 
vec4 processTexture(vec4 tex) {
  vec4 processed = convert_to_rgb(tex);
  { %1 }
  return processed;
}
 
void main() {
  // YUYV packs Y0 U Y1 V into RGBA as x=Y0 y=U z=Y1 w=V
  // Input texture is half the width of the output (one RGBA texel = 2 pixels)
  float colIndex = floor(v_texcoord.x * mat.texSz.x);
  float oddCol = mod(colIndex, 2.0);
 
  // Offset by half an input pixel to sample the correct texel center
  vec2 dxInput = 0.5 * vec2(1.0 / mat.texSz.x, 0.0);
 
  float oddY = texture(u_tex, v_texcoord - dxInput).z;
  float evenY = texture(u_tex, v_texcoord + dxInput).x;
  float y = mix(evenY, oddY, oddCol);
 
  vec2 uv = texture(u_tex, score_tc(v_texcoord)).%3;
 
  fragColor = processTexture(vec4(y, uv.x, uv.y, 1.));
}
)_";
 
  explicit YUYV422Decoder(Video::ImageFormat& d, bool swapChroma = false)
      : decoder{d}
      , yvyu{swapChroma}
  {
  }
 
  Video::ImageFormat& decoder;
  bool yvyu{};
  std::pair<QShader, QShader> init(RenderList& r) override
  {
    auto& rhi = *r.state.rhi;
 
    const auto w = decoder.width, h = decoder.height;
    // Y
    {
      auto tex = rhi.newTexture(QRhiTexture::RGBA8, {w / 2, h}, 1, QRhiTexture::Flag{});
      tex->create();
 
      auto sampler = rhi.newSampler(
          QRhiSampler::Linear, QRhiSampler::Linear, QRhiSampler::None,
          QRhiSampler::ClampToEdge, QRhiSampler::ClampToEdge);
      sampler->create();
      samplers.push_back({sampler, tex});
    }
 
    return score::gfx::makeShaders(
        r.state, vertexShader(),
        QString(frag).arg("").arg(colorMatrix(decoder)).arg(yvyu ? "wy" : "yw"));
  }
 
  void exec(RenderList&, QRhiResourceUpdateBatch& res, AVFrame& frame) override
  {
    setYPixels(res, frame.data[0], frame.linesize[0]);
  }
 
  void
  setYPixels(QRhiResourceUpdateBatch& res, uint8_t* pixels, int stride) const noexcept
  {
    const auto w = decoder.width, h = decoder.height;
    auto y_tex = samplers[0].texture;
 
    // Texture is RGBA8 at {w/2, h}: 4 bytes per texel = one YUYV macropixel
    QRhiTextureUploadEntry entry{0, 0, createTextureUpload(pixels, w / 2, h, 4, stride)};
 
    QRhiTextureUploadDescription desc{entry};
    res.uploadTexture(y_tex, desc);
  }
};
 
struct UYVY422Decoder : GPUVideoDecoder
{
  static const constexpr auto frag = R"_(#version 450
 
)_" SCORE_GFX_VIDEO_UNIFORMS R"_(
 
layout(binding=3) uniform sampler2D u_tex;
 
layout(location = 0) in vec2 v_texcoord;
layout(location = 0) out vec4 fragColor;
 
%2
 
vec4 processTexture(vec4 tex) {
  vec4 processed = convert_to_rgb(tex);
  { %1 }
  return processed;
}
 
void main() {
   // UYVY packs U0 Y0 V0 Y1 into RGBA as x=U0 y=Y0 z=V0 w=Y1
   // Input texture is half the width of the output (one RGBA texel = 2 pixels)
   float colIndex = floor(v_texcoord.x * mat.texSz.x);
   float oddCol = mod(colIndex, 2.0);
 
   // The sampling seam is applied ONCE, to the base coordinate, and the taps
   // are offset from there. score_tc only ever moves y and these offsets are
   // horizontal, so the order does not matter -- but applying it per tap would
   // run the parity arithmetic three times for one answer.
   vec2 tc = score_tc(v_texcoord);
 
   // Offset by half an input pixel to sample the correct texel center
   vec2 dxInput = 0.5 * vec2(1.0 / mat.texSz.x, 0.0);
 
   float oddY = texture(u_tex, tc - dxInput).w;
   float evenY = texture(u_tex, tc + dxInput).y;
   float y = mix(evenY, oddY, oddCol);
 
   vec2 uv = texture(u_tex, tc).%3;
 
  fragColor = processTexture(vec4(y, uv.x, uv.y, 1.));
}
)_";
 
  UYVY422Decoder(Video::ImageFormat& d, bool swapChroma = false)
      : decoder{d}
      , vyuy{swapChroma}
  {
  }
 
  Video::ImageFormat& decoder;
  bool vyuy{};
  std::pair<QShader, QShader> init(RenderList& r) override
  {
    auto& rhi = *r.state.rhi;
 
    const auto w = decoder.width, h = decoder.height;
    // Y
    {
      auto tex = rhi.newTexture(QRhiTexture::RGBA8, {w / 2, h}, 1, QRhiTexture::Flag{});
      tex->create();
 
      auto sampler = rhi.newSampler(
          QRhiSampler::Linear, QRhiSampler::Linear, QRhiSampler::None,
          QRhiSampler::ClampToEdge, QRhiSampler::ClampToEdge);
      sampler->create();
      samplers.push_back({sampler, tex});
    }
 
    return score::gfx::makeShaders(
        r.state, vertexShader(),
        QString(frag).arg("").arg(colorMatrix(decoder)).arg(vyuy ? "zx" : "xz"));
  }
 
  void exec(RenderList&, QRhiResourceUpdateBatch& res, AVFrame& frame) override
  {
    auto y_tex = samplers[0].texture;
 
    auto pixels = frame.data[0];
    auto stride = frame.linesize[0];
    // Texture is RGBA8 at {w/2, h}: 4 bytes per texel = one UYVY macropixel.
    // A fielded source (NDI's "fastest" hands over UYVY fields) fills half of
    // it per frame, top half for field 0, bottom half for field 1.
    const int texW = decoder.width / 2;
    const auto [rows, offset] = planeRows(decoder, frame, decoder.height);
    auto sub = createTextureUpload(pixels, texW, rows, 4, stride);
    sub.setSourceSize({texW, rows});
    sub.setDestinationTopLeft({0, offset});
 
    QRhiTextureUploadDescription desc{QRhiTextureUploadEntry{0, 0, sub}};
    res.uploadTexture(y_tex, desc);
  }
};
 
}