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

   1 #include <Eigen/Core>
   2 #include <Eigen/LU>
   3 #include <epoxy/gl.h>
   4 #include <assert.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7
   8 #include "effect_util.h"
   9 #include "resource_pool.h"
  10 #include "util.h"
  11 #include "ycbcr_input.h"
  12
  13 using namespace Eigen;
  14 using namespace std;
  15
  16 namespace movit {
  17
  18 namespace {
  19
  20 // OpenGL has texel center in (0.5, 0.5), but different formats have
  21 // chroma in various other places. If luma samples are X, the chroma
  22 // sample is *, and subsampling is 3x3, the situation with chroma
  23 // center in (0.5, 0.5) looks approximately like this:
  24 //
  25 //   X   X
  26 //     *
  27 //   X   X
  28 //
  29 // If, on the other hand, chroma center is in (0.0, 0.5) (common
  30 // for e.g. MPEG-4), the figure changes to:
  31 //
  32 //   X   X
  33 //   *
  34 //   X   X
  35 //
  36 // In other words, (0.0, 0.0) means that the chroma sample is exactly
  37 // co-sited on top of the top-left luma sample. Note, however, that
  38 // this is _not_ 0.5 texels to the left, since the OpenGL's texel center
  39 // is in (0.5, 0.5); it is in (0.25, 0.25). In a sense, the four luma samples
  40 // define a square where chroma position (0.0, 0.0) is in texel position
  41 // (0.25, 0.25) and chroma position (1.0, 1.0) is in texel position (0.75, 0.75)
  42 // (the outer border shows the borders of the texel itself, ie. from
  43 // (0, 0) to (1, 1)):
  44 //
  45 //  ---------
  46 // |         |
  47 // |  X---X  |
  48 // |  | * |  |
  49 // |  X---X  |
  50 // |         |
  51 //  ---------
  52 //
  53 // Also note that if we have no subsampling, the square will have zero
  54 // area and the chroma position does not matter at all.
  55 float compute_chroma_offset(float pos, unsigned subsampling_factor, unsigned resolution)
  56 {
  57         float local_chroma_pos = (0.5 + pos * (subsampling_factor - 1)) / subsampling_factor;
  58         return (0.5 - local_chroma_pos) / resolution;
  59 }
  60
  61 }  // namespace
  62
  63 YCbCrInput::YCbCrInput(const ImageFormat &image_format,
  64                        const YCbCrFormat &ycbcr_format,
  65                        unsigned width, unsigned height)
  66         : image_format(image_format),
  67           ycbcr_format(ycbcr_format),
  68           needs_mipmaps(false),
  69           width(width),
  70           height(height),
  71           resource_pool(NULL)
  72 {
  73         pbos[0] = pbos[1] = pbos[2] = 0;
  74         texture_num[0] = texture_num[1] = texture_num[2] = 0;
  75
  76         assert(width % ycbcr_format.chroma_subsampling_x == 0);
  77         pitch[0] = widths[0] = width;
  78         pitch[1] = widths[1] = width / ycbcr_format.chroma_subsampling_x;
  79         pitch[2] = widths[2] = width / ycbcr_format.chroma_subsampling_x;
  80
  81         assert(height % ycbcr_format.chroma_subsampling_y == 0);
  82         heights[0] = height;
  83         heights[1] = height / ycbcr_format.chroma_subsampling_y;
  84         heights[2] = height / ycbcr_format.chroma_subsampling_y;
  85
  86         pixel_data[0] = pixel_data[1] = pixel_data[2] = NULL;
  87
  88         register_int("needs_mipmaps", &needs_mipmaps);
  89 }
  90
  91 YCbCrInput::~YCbCrInput()
  92 {
  93         for (unsigned channel = 0; channel < 3; ++channel) {
  94                 if (texture_num[channel] != 0) {
  95                         resource_pool->release_2d_texture(texture_num[channel]);
  96                 }
  97         }
  98 }
  99
 100 void YCbCrInput::set_gl_state(GLuint glsl_program_num, const string& prefix, unsigned *sampler_num)
 101 {
 102         for (unsigned channel = 0; channel < 3; ++channel) {
 103                 glActiveTexture(GL_TEXTURE0 + *sampler_num + channel);
 104                 check_error();
 105
 106                 if (texture_num[channel] == 0) {
 107                         // (Re-)upload the texture.
 108                         texture_num[channel] = resource_pool->create_2d_texture(GL_R8, widths[channel], heights[channel]);
 109                         glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
 110                         check_error();
 111                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 112                         check_error();
 113                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
 114                         check_error();
 115                         glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 116                         check_error();
 117                         glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
 118                         check_error();
 119                         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], GL_RED, GL_UNSIGNED_BYTE, pixel_data[channel]);
 120                         check_error();
 121                         glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
 122                         check_error();
 123                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 124                         check_error();
 125                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 126                         check_error();
 127                 } else {
 128                         glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
 129                         check_error();
 130                 }
 131         }
 132
 133         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
 134         check_error();
 135
 136         // Bind samplers.
 137         set_uniform_int(glsl_program_num, prefix, "tex_y", *sampler_num + 0);
 138         set_uniform_int(glsl_program_num, prefix, "tex_cb", *sampler_num + 1);
 139         set_uniform_int(glsl_program_num, prefix, "tex_cr", *sampler_num + 2);
 140
 141         *sampler_num += 3;
 142 }
 143
 144 string YCbCrInput::output_fragment_shader()
 145 {
 146         float coeff[3], offset[3], scale[3];
 147
 148         switch (ycbcr_format.luma_coefficients) {
 149         case YCBCR_REC_601:
 150                 // Rec. 601, page 2.
 151                 coeff[0] = 0.299;
 152                 coeff[1] = 0.587;
 153                 coeff[2] = 0.114;
 154                 break;
 155
 156         case YCBCR_REC_709:
 157                 // Rec. 709, page 19.
 158                 coeff[0] = 0.2126;
 159                 coeff[1] = 0.7152;
 160                 coeff[2] = 0.0722;
 161                 break;
 162
 163         case YCBCR_REC_2020:
 164                 // Rec. 2020, page 4.
 165                 coeff[0] = 0.2627;
 166                 coeff[1] = 0.6780;
 167                 coeff[2] = 0.0593;
 168                 break;
 169
 170         default:
 171                 assert(false);
 172         }
 173
 174         if (ycbcr_format.full_range) {
 175                 offset[0] = 0.0 / 255.0;
 176                 offset[1] = 128.0 / 255.0;
 177                 offset[2] = 128.0 / 255.0;
 178
 179                 scale[0] = 1.0;
 180                 scale[1] = 1.0;
 181                 scale[2] = 1.0;
 182         } else {
 183                 // Rec. 601, page 4; Rec. 709, page 19; Rec. 2020, page 4.
 184                 offset[0] = 16.0 / 255.0;
 185                 offset[1] = 128.0 / 255.0;
 186                 offset[2] = 128.0 / 255.0;
 187
 188                 scale[0] = 255.0 / 219.0;
 189                 scale[1] = 255.0 / 224.0;
 190                 scale[2] = 255.0 / 224.0;
 191         }
 192
 193         // Matrix to convert RGB to YCbCr. See e.g. Rec. 601.
 194         Matrix3d rgb_to_ycbcr;
 195         rgb_to_ycbcr(0,0) = coeff[0];
 196         rgb_to_ycbcr(0,1) = coeff[1];
 197         rgb_to_ycbcr(0,2) = coeff[2];
 198
 199         float cb_fac = (224.0 / 219.0) / (coeff[0] + coeff[1] + 1.0f - coeff[2]);
 200         rgb_to_ycbcr(1,0) = -coeff[0] * cb_fac;
 201         rgb_to_ycbcr(1,1) = -coeff[1] * cb_fac;
 202         rgb_to_ycbcr(1,2) = (1.0f - coeff[2]) * cb_fac;
 203
 204         float cr_fac = (224.0 / 219.0) / (1.0f - coeff[0] + coeff[1] + coeff[2]);
 205         rgb_to_ycbcr(2,0) = (1.0f - coeff[0]) * cr_fac;
 206         rgb_to_ycbcr(2,1) = -coeff[1] * cr_fac;
 207         rgb_to_ycbcr(2,2) = -coeff[2] * cr_fac;
 208
 209         // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
 210         Matrix3d ycbcr_to_rgb = rgb_to_ycbcr.inverse();
 211
 212         string frag_shader;
 213
 214         frag_shader = output_glsl_mat3("PREFIX(inv_ycbcr_matrix)", ycbcr_to_rgb);
 215
 216         char buf[256];
 217         sprintf(buf, "const vec3 PREFIX(offset) = vec3(%.8f, %.8f, %.8f);\n",
 218                 offset[0], offset[1], offset[2]);
 219         frag_shader += buf;
 220
 221         sprintf(buf, "const vec3 PREFIX(scale) = vec3(%.8f, %.8f, %.8f);\n",
 222                 scale[0], scale[1], scale[2]);
 223         frag_shader += buf;
 224
 225         float cb_offset_x = compute_chroma_offset(
 226                 ycbcr_format.cb_x_position, ycbcr_format.chroma_subsampling_x, widths[1]);
 227         float cb_offset_y = compute_chroma_offset(
 228                 ycbcr_format.cb_y_position, ycbcr_format.chroma_subsampling_y, heights[1]);
 229         sprintf(buf, "const vec2 PREFIX(cb_offset) = vec2(%.8f, %.8f);\n",
 230                 cb_offset_x, cb_offset_y);
 231         frag_shader += buf;
 232
 233         float cr_offset_x = compute_chroma_offset(
 234                 ycbcr_format.cr_x_position, ycbcr_format.chroma_subsampling_x, widths[2]);
 235         float cr_offset_y = compute_chroma_offset(
 236                 ycbcr_format.cr_y_position, ycbcr_format.chroma_subsampling_y, heights[2]);
 237         sprintf(buf, "const vec2 PREFIX(cr_offset) = vec2(%.8f, %.8f);\n",
 238                 cr_offset_x, cr_offset_y);
 239         frag_shader += buf;
 240
 241         frag_shader += read_file("ycbcr_input.frag");
 242         return frag_shader;
 243 }
 244
 245 void YCbCrInput::invalidate_pixel_data()
 246 {
 247         for (unsigned channel = 0; channel < 3; ++channel) {
 248                 if (texture_num[channel] != 0) {
 249                         resource_pool->release_2d_texture(texture_num[channel]);
 250                         texture_num[channel] = 0;
 251                 }
 252         }
 253 }
 254
 255 }  // namespace movit