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         pbos[0] = pbos[1] = pbos[2] = 0;
  21         texture_num[0] = texture_num[1] = texture_num[2] = 0;
  22
  23         pitch[0] = pitch[1] = pitch[2] = width;
  24
  25         assert(width % ycbcr_format.chroma_subsampling_x == 0);
  26         widths[0] = width;
  27         widths[1] = width / ycbcr_format.chroma_subsampling_x;
  28         widths[2] = width / ycbcr_format.chroma_subsampling_x;
  29
  30         assert(height % ycbcr_format.chroma_subsampling_y == 0);
  31         heights[0] = height;
  32         heights[1] = height / ycbcr_format.chroma_subsampling_y;
  33         heights[2] = height / ycbcr_format.chroma_subsampling_y;
  34
  35         register_int("needs_mipmaps", &needs_mipmaps);
  36 }
  37
  38 YCbCrInput::~YCbCrInput()
  39 {
  40         if (pbos[0] != 0) {
  41                 glDeleteBuffers(3, pbos);
  42                 check_error();
  43         }
  44         if (texture_num[0] != 0) {
  45                 glDeleteTextures(3, texture_num);
  46                 check_error();
  47         }
  48 }
  49
  50 void YCbCrInput::finalize()
  51 {
  52         glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  53         check_error();
  54
  55         // Create PBOs to hold the textures holding the input image, and then the texture itself.
  56         glGenBuffers(3, pbos);
  57         check_error();
  58         glGenTextures(3, texture_num);
  59         check_error();
  60
  61         for (unsigned channel = 0; channel < 3; ++channel) {
  62                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
  63                 check_error();
  64                 glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, pitch[channel] * heights[channel], NULL, GL_STREAM_DRAW);
  65                 check_error();
  66                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
  67                 check_error();
  68
  69                 glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
  70                 check_error();
  71                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  72                 check_error();
  73                 glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
  74                 check_error();
  75                 glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE8, widths[channel], heights[channel], 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
  76                 check_error();
  77                 glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  78                 check_error();
  79         }
  80
  81         needs_update = false;
  82         finalized = true;
  83 }
  84
  85 void YCbCrInput::set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num)
  86 {
  87         for (unsigned channel = 0; channel < 3; ++channel) {
  88                 glActiveTexture(GL_TEXTURE0 + *sampler_num + channel);
  89                 check_error();
  90                 glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
  91                 check_error();
  92
  93                 if (needs_update || needs_pbo_recreate) {
  94                         // Copy the pixel data into the PBO.
  95                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
  96                         check_error();
  97
  98                         if (needs_pbo_recreate) {
  99                                 // The pitch has changed; we need to reallocate this PBO.
 100                                 glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, pitch[channel] * heights[channel], NULL, GL_STREAM_DRAW);
 101                                 check_error();
 102                         }
 103
 104                         void *mapped_pbo = glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, GL_WRITE_ONLY);
 105                         memcpy(mapped_pbo, pixel_data[channel], pitch[channel] * heights[channel]);
 106
 107                         glUnmapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB);
 108                         check_error();
 109
 110                         // Re-upload the texture from the PBO.
 111                         glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
 112                         check_error();
 113                         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], GL_LUMINANCE, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0));
 114                         check_error();
 115                         glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
 116                         check_error();
 117                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 118                         check_error();
 119                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 120                         check_error();
 121                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
 122                         check_error();
 123                 }
 124         }
 125
 126         // Bind samplers.
 127         set_uniform_int(glsl_program_num, prefix, "tex_y", *sampler_num + 0);
 128         set_uniform_int(glsl_program_num, prefix, "tex_cb", *sampler_num + 1);
 129         set_uniform_int(glsl_program_num, prefix, "tex_cr", *sampler_num + 2);
 130
 131         *sampler_num += 3;
 132         needs_update = false;
 133         needs_pbo_recreate = false;
 134 }
 135
 136 std::string YCbCrInput::output_fragment_shader()
 137 {
 138         float coeff[3], offset[3], scale[3];
 139
 140         switch (ycbcr_format.luma_coefficients) {
 141         case YCBCR_REC_601:
 142                 // Rec. 601, page 2.
 143                 coeff[0] = 0.299;
 144                 coeff[1] = 0.587;
 145                 coeff[2] = 0.114;
 146                 break;
 147
 148         case YCBCR_REC_709:
 149                 // Rec. 709, page 19.
 150                 coeff[0] = 0.2126;
 151                 coeff[1] = 0.7152;
 152                 coeff[2] = 0.0722;
 153                 break;
 154         default:
 155                 assert(false);
 156         }
 157
 158         if (ycbcr_format.full_range) {
 159                 offset[0] = 0.0 / 255.0;
 160                 offset[1] = 128.0 / 255.0;
 161                 offset[2] = 128.0 / 255.0;
 162
 163                 scale[0] = 1.0;
 164                 scale[1] = 1.0;
 165                 scale[2] = 1.0;
 166         } else {
 167                 // Rec. 601, page 4; Rec. 709, page 19.
 168                 offset[0] = 16.0 / 255.0;
 169                 offset[1] = 128.0 / 255.0;
 170                 offset[2] = 128.0 / 255.0;
 171
 172                 scale[0] = 255.0 / 219.0;
 173                 scale[1] = 255.0 / 224.0;
 174                 scale[2] = 255.0 / 224.0;
 175         }
 176
 177         // Matrix to convert RGB to YCbCr. See e.g. Rec. 601.
 178         Matrix3x3 rgb_to_ycbcr;
 179         rgb_to_ycbcr[0] = coeff[0];
 180         rgb_to_ycbcr[3] = coeff[1];
 181         rgb_to_ycbcr[6] = coeff[2];
 182
 183         float cb_fac = (224.0 / 219.0) / (coeff[0] + coeff[1] + 1.0f - coeff[2]);
 184         rgb_to_ycbcr[1] = -coeff[0] * cb_fac;
 185         rgb_to_ycbcr[4] = -coeff[1] * cb_fac;
 186         rgb_to_ycbcr[7] = (1.0f - coeff[2]) * cb_fac;
 187
 188         float cr_fac = (224.0 / 219.0) / (1.0f - coeff[0] + coeff[1] + coeff[2]);
 189         rgb_to_ycbcr[2] = (1.0f - coeff[0]) * cr_fac;
 190         rgb_to_ycbcr[5] = -coeff[1] * cr_fac;
 191         rgb_to_ycbcr[8] = -coeff[2] * cr_fac;
 192
 193         // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
 194         Matrix3x3 ycbcr_to_rgb;
 195         invert_3x3_matrix(rgb_to_ycbcr, ycbcr_to_rgb);
 196
 197         std::string frag_shader;
 198
 199         char buf[1024];
 200         sprintf(buf,
 201                 "const mat3 PREFIX(inv_ycbcr_matrix) = mat3(\n"
 202                 "    %.8f, %.8f, %.8f,\n"
 203                 "    %.8f, %.8f, %.8f,\n"
 204                 "    %.8f, %.8f, %.8f);\n",
 205                 ycbcr_to_rgb[0], ycbcr_to_rgb[1], ycbcr_to_rgb[2],
 206                 ycbcr_to_rgb[3], ycbcr_to_rgb[4], ycbcr_to_rgb[5],
 207                 ycbcr_to_rgb[6], ycbcr_to_rgb[7], ycbcr_to_rgb[8]);
 208         frag_shader = buf;
 209
 210         sprintf(buf, "const vec3 PREFIX(offset) = vec3(%.8f, %.8f, %.8f);\n",
 211                 offset[0], offset[1], offset[2]);
 212         frag_shader += buf;
 213
 214         sprintf(buf, "const vec3 PREFIX(scale) = vec3(%.8f, %.8f, %.8f);\n",
 215                 scale[0], scale[1], scale[2]);
 216         frag_shader += buf;
 217
 218         // OpenGL has texel center in (0.5, 0.5), but different formats have
 219         // chroma in various other places. If luma samples are X, the chroma
 220         // sample is *, and subsampling is 3x3, the situation with chroma
 221         // center in (0.5, 0.5) looks approximately like this:
 222         //
 223         //   X     X
 224         //      *
 225         //   X     X
 226         //
 227         // If, on the other hand, chroma center is in (0.0, 0.5) (common
 228         // for e.g. MPEG-4), the figure changes to:
 229         //
 230         //   X     X
 231         //   *
 232         //   X     X
 233         //
 234         // Obviously, the chroma plane here needs to be moved to the left,
 235         // which means _adding_ 0.5 to the texture coordinates when sampling
 236         // chroma.
 237         float chroma_offset_x = (0.5f - ycbcr_format.chroma_x_position) / widths[1];
 238         float chroma_offset_y = (0.5f - ycbcr_format.chroma_y_position) / heights[1];
 239         sprintf(buf, "const vec2 PREFIX(chroma_offset) = vec2(%.8f, %.8f);\n",
 240                 chroma_offset_x, chroma_offset_y);
 241         frag_shader += buf;
 242
 243         frag_shader += read_file("ycbcr_input.frag");
 244         return frag_shader;
 245 }