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