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

   1 #include <string.h>
   2 #include <assert.h>
   3
   4 #include <Eigen/LU>
   5
   6 #include "ycbcr_input.h"
   7 #include "util.h"
   8 #include "opengl.h"
   9
  10 using namespace Eigen;
  11
  12 YCbCrInput::YCbCrInput(const ImageFormat &image_format,
  13                        const YCbCrFormat &ycbcr_format,
  14                        unsigned width, unsigned height)
  15         : image_format(image_format),
  16           ycbcr_format(ycbcr_format),
  17           needs_update(false),
  18           needs_pbo_recreate(false),
  19           finalized(false),
  20           needs_mipmaps(false),
  21           width(width),
  22           height(height)
  23 {
  24         pbos[0] = pbos[1] = pbos[2] = 0;
  25         texture_num[0] = texture_num[1] = texture_num[2] = 0;
  26
  27         pitch[0] = pitch[1] = pitch[2] = width;
  28
  29         assert(width % ycbcr_format.chroma_subsampling_x == 0);
  30         widths[0] = width;
  31         widths[1] = width / ycbcr_format.chroma_subsampling_x;
  32         widths[2] = width / ycbcr_format.chroma_subsampling_x;
  33
  34         assert(height % ycbcr_format.chroma_subsampling_y == 0);
  35         heights[0] = height;
  36         heights[1] = height / ycbcr_format.chroma_subsampling_y;
  37         heights[2] = height / ycbcr_format.chroma_subsampling_y;
  38
  39         register_int("needs_mipmaps", &needs_mipmaps);
  40 }
  41
  42 YCbCrInput::~YCbCrInput()
  43 {
  44         if (pbos[0] != 0) {
  45                 glDeleteBuffers(3, pbos);
  46                 check_error();
  47         }
  48         if (texture_num[0] != 0) {
  49                 glDeleteTextures(3, texture_num);
  50                 check_error();
  51         }
  52 }
  53
  54 void YCbCrInput::finalize()
  55 {
  56         glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  57         check_error();
  58
  59         // Create PBOs to hold the textures holding the input image, and then the texture itself.
  60         glGenBuffers(3, pbos);
  61         check_error();
  62         glGenTextures(3, texture_num);
  63         check_error();
  64
  65         for (unsigned channel = 0; channel < 3; ++channel) {
  66                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
  67                 check_error();
  68                 glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, pitch[channel] * heights[channel], NULL, GL_STREAM_DRAW);
  69                 check_error();
  70                 glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
  71                 check_error();
  72
  73                 glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
  74                 check_error();
  75                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  76                 check_error();
  77                 glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
  78                 check_error();
  79                 glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE8, widths[channel], heights[channel], 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, NULL);
  80                 check_error();
  81                 glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  82                 check_error();
  83         }
  84
  85         needs_update = false;
  86         finalized = true;
  87 }
  88
  89 void YCbCrInput::set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num)
  90 {
  91         for (unsigned channel = 0; channel < 3; ++channel) {
  92                 glActiveTexture(GL_TEXTURE0 + *sampler_num + channel);
  93                 check_error();
  94                 glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
  95                 check_error();
  96
  97                 if (needs_update || needs_pbo_recreate) {
  98                         // Copy the pixel data into the PBO.
  99                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
 100                         check_error();
 101
 102                         if (needs_pbo_recreate) {
 103                                 // The pitch has changed; we need to reallocate this PBO.
 104                                 glBufferData(GL_PIXEL_UNPACK_BUFFER_ARB, pitch[channel] * heights[channel], NULL, GL_STREAM_DRAW);
 105                                 check_error();
 106                         }
 107
 108                         void *mapped_pbo = glMapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB, GL_WRITE_ONLY);
 109                         memcpy(mapped_pbo, pixel_data[channel], pitch[channel] * heights[channel]);
 110
 111                         glUnmapBufferARB(GL_PIXEL_UNPACK_BUFFER_ARB);
 112                         check_error();
 113
 114                         // Re-upload the texture from the PBO.
 115                         glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
 116                         check_error();
 117                         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], GL_LUMINANCE, GL_UNSIGNED_BYTE, BUFFER_OFFSET(0));
 118                         check_error();
 119                         glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
 120                         check_error();
 121                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 122                         check_error();
 123                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 124                         check_error();
 125                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
 126                         check_error();
 127                 }
 128         }
 129
 130         // Bind samplers.
 131         set_uniform_int(glsl_program_num, prefix, "tex_y", *sampler_num + 0);
 132         set_uniform_int(glsl_program_num, prefix, "tex_cb", *sampler_num + 1);
 133         set_uniform_int(glsl_program_num, prefix, "tex_cr", *sampler_num + 2);
 134
 135         *sampler_num += 3;
 136         needs_update = false;
 137         needs_pbo_recreate = false;
 138 }
 139
 140 std::string YCbCrInput::output_fragment_shader()
 141 {
 142         float coeff[3], offset[3], scale[3];
 143
 144         switch (ycbcr_format.luma_coefficients) {
 145         case YCBCR_REC_601:
 146                 // Rec. 601, page 2.
 147                 coeff[0] = 0.299;
 148                 coeff[1] = 0.587;
 149                 coeff[2] = 0.114;
 150                 break;
 151
 152         case YCBCR_REC_709:
 153                 // Rec. 709, page 19.
 154                 coeff[0] = 0.2126;
 155                 coeff[1] = 0.7152;
 156                 coeff[2] = 0.0722;
 157                 break;
 158         default:
 159                 assert(false);
 160         }
 161
 162         if (ycbcr_format.full_range) {
 163                 offset[0] = 0.0 / 255.0;
 164                 offset[1] = 128.0 / 255.0;
 165                 offset[2] = 128.0 / 255.0;
 166
 167                 scale[0] = 1.0;
 168                 scale[1] = 1.0;
 169                 scale[2] = 1.0;
 170         } else {
 171                 // Rec. 601, page 4; Rec. 709, page 19.
 172                 offset[0] = 16.0 / 255.0;
 173                 offset[1] = 128.0 / 255.0;
 174                 offset[2] = 128.0 / 255.0;
 175
 176                 scale[0] = 255.0 / 219.0;
 177                 scale[1] = 255.0 / 224.0;
 178                 scale[2] = 255.0 / 224.0;
 179         }
 180
 181         // Matrix to convert RGB to YCbCr. See e.g. Rec. 601.
 182         Matrix3d rgb_to_ycbcr;
 183         rgb_to_ycbcr(0,0) = coeff[0];
 184         rgb_to_ycbcr(0,1) = coeff[1];
 185         rgb_to_ycbcr(0,2) = coeff[2];
 186
 187         float cb_fac = (224.0 / 219.0) / (coeff[0] + coeff[1] + 1.0f - coeff[2]);
 188         rgb_to_ycbcr(1,0) = -coeff[0] * cb_fac;
 189         rgb_to_ycbcr(1,1) = -coeff[1] * cb_fac;
 190         rgb_to_ycbcr(1,2) = (1.0f - coeff[2]) * cb_fac;
 191
 192         float cr_fac = (224.0 / 219.0) / (1.0f - coeff[0] + coeff[1] + coeff[2]);
 193         rgb_to_ycbcr(2,0) = (1.0f - coeff[0]) * cr_fac;
 194         rgb_to_ycbcr(2,1) = -coeff[1] * cr_fac;
 195         rgb_to_ycbcr(2,2) = -coeff[2] * cr_fac;
 196
 197         // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
 198         Matrix3d ycbcr_to_rgb = rgb_to_ycbcr.inverse();
 199
 200         std::string frag_shader;
 201
 202         frag_shader = output_glsl_mat3("PREFIX(inv_ycbcr_matrix)", ycbcr_to_rgb);
 203
 204         char buf[256];
 205         sprintf(buf, "const vec3 PREFIX(offset) = vec3(%.8f, %.8f, %.8f);\n",
 206                 offset[0], offset[1], offset[2]);
 207         frag_shader += buf;
 208
 209         sprintf(buf, "const vec3 PREFIX(scale) = vec3(%.8f, %.8f, %.8f);\n",
 210                 scale[0], scale[1], scale[2]);
 211         frag_shader += buf;
 212
 213         // OpenGL has texel center in (0.5, 0.5), but different formats have
 214         // chroma in various other places. If luma samples are X, the chroma
 215         // sample is *, and subsampling is 3x3, the situation with chroma
 216         // center in (0.5, 0.5) looks approximately like this:
 217         //
 218         //   X     X
 219         //      *
 220         //   X     X
 221         //
 222         // If, on the other hand, chroma center is in (0.0, 0.5) (common
 223         // for e.g. MPEG-4), the figure changes to:
 224         //
 225         //   X     X
 226         //   *
 227         //   X     X
 228         //
 229         // Obviously, the chroma plane here needs to be moved to the left,
 230         // which means _adding_ 0.5 to the texture coordinates when sampling
 231         // chroma.
 232         float chroma_offset_x = (0.5f - ycbcr_format.chroma_x_position) / widths[1];
 233         float chroma_offset_y = (0.5f - ycbcr_format.chroma_y_position) / heights[1];
 234         sprintf(buf, "const vec2 PREFIX(chroma_offset) = vec2(%.8f, %.8f);\n",
 235                 chroma_offset_x, chroma_offset_y);
 236         frag_shader += buf;
 237
 238         frag_shader += read_file("ycbcr_input.frag");
 239         return frag_shader;
 240 }