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