git.sesse.net Git - movit/blob - ycbcr_input.cpp

   1 #include <string.h>
   2 #include <assert.h>
   3
   4 #include "ycbcr_input.h"
   5 #include "util.h"
   6 #include "opengl.h"
   7
   8 YCbCrInput::YCbCrInput(const ImageFormat &image_format,
   9                        const YCbCrFormat &ycbcr_format,
  10                        unsigned width, unsigned height)
  11         : image_format(image_format),
  12           ycbcr_format(ycbcr_format),
  13           needs_update(false),
  14           needs_pbo_recreate(false),
  15           finalized(false),
  16           needs_mipmaps(false),
  17           width(width),
  18           height(height)
  19 {
  20         pitch[0] = pitch[1] = pitch[2] = width;
  21
  22         assert(width % ycbcr_format.chroma_subsampling_x == 0);
  23         widths[0] = width;
  24         widths[1] = width / ycbcr_format.chroma_subsampling_x;
  25         widths[2] = width / ycbcr_format.chroma_subsampling_x;
  26
  27         assert(height % ycbcr_format.chroma_subsampling_y == 0);
  28         heights[0] = height;
  29         heights[1] = height / ycbcr_format.chroma_subsampling_y;
  30         heights[2] = height / ycbcr_format.chroma_subsampling_y;
  31
  32         register_int("needs_mipmaps", &needs_mipmaps);
  33 }
  34
  35 void YCbCrInput::finalize()
  36 {
  37         // Create PBOs to hold the textures holding the input image, and then the texture itself.
  38         glGenBuffers(3, pbos);
  39         check_error();
  40         glGenTextures(3, texture_num);
  41         check_error();
  42
  43         for (unsigned channel = 0; channel < 3; ++channel) {
  44                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
  45                 check_error();
  46                 glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, pitch[channel] * heights[channel], NULL, GL_STREAM_DRAW);
  47                 check_error();
  48                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
  49                 check_error();
  50
  51                 glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
  52                 check_error();
  53                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  54                 check_error();
  55                 glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
  56                 check_error();
  57                 glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE8, widths[channel], heights[channel], 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
  58                 check_error();
  59                 glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  60                 check_error();
  61         }
  62
  63         needs_update = false;
  64         finalized = true;
  65 }
  66
  67 void YCbCrInput::set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num)
  68 {
  69         for (unsigned channel = 0; channel < 3; ++channel) {
  70                 glActiveTexture(GL_TEXTURE0 + *sampler_num + channel);
  71                 check_error();
  72                 glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
  73                 check_error();
  74
  75                 if (needs_update || needs_pbo_recreate) {
  76                         // Copy the pixel data into the PBO.
  77                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
  78                         check_error();
  79
  80                         if (needs_pbo_recreate) {
  81                                 // The pitch has changed; we need to reallocate this PBO.
  82                                 glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, pitch[channel] * heights[channel], NULL, GL_STREAM_DRAW);
  83                                 check_error();
  84                         }
  85
  86                         void *mapped_pbo = glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, GL_WRITE_ONLY);
  87                         memcpy(mapped_pbo, pixel_data[channel], pitch[channel] * heights[channel]);
  88
  89                         glUnmapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB);
  90                         check_error();
  91
  92                         // Re-upload the texture from the PBO.
  93                         glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
  94                         check_error();
  95                         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], GL_LUMINANCE, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0));
  96                         check_error();
  97                         glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  98                         check_error();
  99                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 100                         check_error();
 101                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 102                         check_error();
 103                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
 104                         check_error();
 105                 }
 106         }
 107
 108         // Bind samplers.
 109         set_uniform_int(glsl_program_num, prefix, "tex_y", *sampler_num + 0);
 110         set_uniform_int(glsl_program_num, prefix, "tex_cb", *sampler_num + 1);
 111         set_uniform_int(glsl_program_num, prefix, "tex_cr", *sampler_num + 2);
 112
 113         *sampler_num += 3;
 114         needs_update = false;
 115         needs_pbo_recreate = false;
 116 }
 117
 118 std::string YCbCrInput::output_fragment_shader()
 119 {
 120         float coeff[3], offset[3], scale[3];
 121
 122         switch (ycbcr_format.luma_coefficients) {
 123         case YCBCR_REC_601:
 124                 // Rec. 601, page 2.
 125                 coeff[0] = 0.299;
 126                 coeff[1] = 0.587;
 127                 coeff[2] = 0.114;
 128                 break;
 129
 130         case YCBCR_REC_709:
 131                 // Rec. 709, page 19.
 132                 coeff[0] = 0.2126;
 133                 coeff[1] = 0.7152;
 134                 coeff[2] = 0.0722;
 135                 break;
 136         default:
 137                 assert(false);
 138         }
 139
 140         if (ycbcr_format.full_range) {
 141                 offset[0] = 0.0 / 255.0;
 142                 offset[1] = 128.0 / 255.0;
 143                 offset[2] = 128.0 / 255.0;
 144
 145                 scale[0] = 1.0;
 146                 scale[1] = 1.0;
 147                 scale[2] = 1.0;
 148         } else {
 149                 // Rec. 601, page 4; Rec. 709, page 19.
 150                 offset[0] = 16.0 / 255.0;
 151                 offset[1] = 128.0 / 255.0;
 152                 offset[2] = 128.0 / 255.0;
 153
 154                 scale[0] = 255.0 / 219.0;
 155                 scale[1] = 255.0 / 224.0;
 156                 scale[2] = 255.0 / 224.0;
 157         }
 158
 159         // Matrix to convert RGB to YCbCr. See e.g. Rec. 601.
 160         Matrix3x3 rgb_to_ycbcr;
 161         rgb_to_ycbcr[0] = coeff[0];
 162         rgb_to_ycbcr[3] = coeff[1];
 163         rgb_to_ycbcr[6] = coeff[2];
 164
 165         float cb_fac = (224.0 / 219.0) / (coeff[0] + coeff[1] + 1.0f - coeff[2]);
 166         rgb_to_ycbcr[1] = -coeff[0] * cb_fac;
 167         rgb_to_ycbcr[4] = -coeff[1] * cb_fac;
 168         rgb_to_ycbcr[7] = (1.0f - coeff[2]) * cb_fac;
 169
 170         float cr_fac = (224.0 / 219.0) / (1.0f - coeff[0] + coeff[1] + coeff[2]);
 171         rgb_to_ycbcr[2] = (1.0f - coeff[0]) * cr_fac;
 172         rgb_to_ycbcr[5] = -coeff[1] * cr_fac;
 173         rgb_to_ycbcr[8] = -coeff[2] * cr_fac;
 174
 175         // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
 176         Matrix3x3 ycbcr_to_rgb;
 177         invert_3x3_matrix(rgb_to_ycbcr, ycbcr_to_rgb);
 178
 179         std::string frag_shader;
 180
 181         char buf[1024];
 182         sprintf(buf,
 183                 "const mat3 PREFIX(inv_ycbcr_matrix) = mat3(\n"
 184                 "    %.8f, %.8f, %.8f,\n"
 185                 "    %.8f, %.8f, %.8f,\n"
 186                 "    %.8f, %.8f, %.8f);\n",
 187                 ycbcr_to_rgb[0], ycbcr_to_rgb[1], ycbcr_to_rgb[2],
 188                 ycbcr_to_rgb[3], ycbcr_to_rgb[4], ycbcr_to_rgb[5],
 189                 ycbcr_to_rgb[6], ycbcr_to_rgb[7], ycbcr_to_rgb[8]);
 190         frag_shader = buf;
 191
 192         sprintf(buf, "const vec3 PREFIX(offset) = vec3(%.8f, %.8f, %.8f);\n",
 193                 offset[0], offset[1], offset[2]);
 194         frag_shader += buf;
 195
 196         sprintf(buf, "const vec3 PREFIX(scale) = vec3(%.8f, %.8f, %.8f);\n",
 197                 scale[0], scale[1], scale[2]);
 198         frag_shader += buf;
 199
 200         // OpenGL has texel center in (0.5, 0.5), but different formats have
 201         // chroma in various other places. If luma samples are X, the chroma
 202         // sample is *, and subsampling is 3x3, the situation with chroma
 203         // center in (0.5, 0.5) looks approximately like this:
 204         //
 205         //   X     X
 206         //      *
 207         //   X     X
 208         //
 209         // If, on the other hand, chroma center is in (0.0, 0.5) (common
 210         // for e.g. MPEG-4), the figure changes to:
 211         //
 212         //   X     X
 213         //   *
 214         //   X     X
 215         //
 216         // Obviously, the chroma plane here needs to be moved to the left,
 217         // which means _adding_ 0.5 to the texture coordinates when sampling
 218         // chroma.
 219         float chroma_offset_x = (0.5f - ycbcr_format.chroma_x_position) / widths[1];
 220         float chroma_offset_y = (0.5f - ycbcr_format.chroma_y_position) / heights[1];
 221         sprintf(buf, "const vec2 PREFIX(chroma_offset) = vec2(%.8f, %.8f);\n",
 222                 chroma_offset_x, chroma_offset_y);
 223         frag_shader += buf;
 224
 225         frag_shader += read_file("ycbcr_input.frag");
 226         return frag_shader;
 227 }