PA16.hpp

#pragma once
#include <Gfx/Graph/decoders/ColorSpace.hpp>
#include <Gfx/Graph/decoders/GPUVideoDecoder.hpp>
 
namespace score::gfx
{
 
struct PA16Decoder : GPUVideoDecoder
{
  static const constexpr auto frag = R"_(#version 450
 
)_" SCORE_GFX_VIDEO_UNIFORMS R"_(
 
layout(binding=3) uniform sampler2D y_tex;
layout(binding=4) uniform sampler2D uv_tex;
layout(binding=5) uniform sampler2D a_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() {
  vec2 tc = score_tc(v_texcoord);
  // The colour planes are P216's, MSB-aligned 8-bit codes; the alpha plane is
  // full range for its data type, so it is already 0..1.
  const float s = )_" SCORE_GFX_MSB_ALIGNED_SCALE R"_(;
  float y = s * texture(y_tex, tc).r;
  float u = s * texture(uv_tex, tc).r;
  float v = s * texture(uv_tex, tc).g;
  float a = texture(a_tex, tc).r;
 
  vec4 rgb = processTexture(vec4(y, u, v, 1.));
  fragColor = vec4(rgb.rgb, a);
}
)_";
 
  explicit PA16Decoder(Video::ImageFormat& d)
      : decoder{d}
  {
  }
 
  Video::ImageFormat& decoder;
 
  std::pair<QShader, QShader> init(RenderList& r) override
  {
    auto& rhi = *r.state.rhi;
    const auto w = decoder.width, h = decoder.height;
 
    auto mkSampler = [&] {
      auto sampler = rhi.newSampler(
          QRhiSampler::Linear, QRhiSampler::Linear, QRhiSampler::None,
          QRhiSampler::ClampToEdge, QRhiSampler::ClampToEdge);
      sampler->create();
      return sampler;
    };
    auto plane = [&](QRhiTexture::Format fmt, QSize sz) {
      auto tex = rhi.newTexture(fmt, sz, 1, QRhiTexture::Flag{});
      tex->create();
      samplers.push_back({mkSampler(), tex});
    };
 
    plane(QRhiTexture::R16, {w, h});       // Y
    plane(QRhiTexture::RG16, {w / 2, h});  // interleaved CbCr
    plane(QRhiTexture::R16, {w, h});       // A
 
    return score::gfx::makeShaders(
        r.state, vertexShader(), QString(frag).arg("").arg(colorMatrix(decoder)));
  }
 
  void exec(RenderList&, QRhiResourceUpdateBatch& res, AVFrame& frame) override
  {
    const int widths[3] = {decoder.width, decoder.width / 2, decoder.width};
    const int bpt[3] = {2, 4, 2};
    for(int i = 0; i < 3; i++)
    {
      const auto [rows, offset] = planeRows(decoder, frame, decoder.height);
      auto sub = createTextureUpload(
          frame.data[i], widths[i], rows, bpt[i], frame.linesize[i]);
      sub.setDestinationTopLeft({0, offset});
      res.uploadTexture(samplers[i].texture, QRhiTextureUploadDescription{{0, 0, sub}});
    }
  }
};
 
}