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           width(width),
  69           height(height),
  70           resource_pool(NULL)
  71 {
  72         pbos[0] = pbos[1] = pbos[2] = 0;
  73         texture_num[0] = texture_num[1] = texture_num[2] = 0;
  74
  75         assert(width % ycbcr_format.chroma_subsampling_x == 0);
  76         pitch[0] = widths[0] = width;
  77         pitch[1] = widths[1] = width / ycbcr_format.chroma_subsampling_x;
  78         pitch[2] = widths[2] = width / ycbcr_format.chroma_subsampling_x;
  79
  80         assert(height % ycbcr_format.chroma_subsampling_y == 0);
  81         heights[0] = height;
  82         heights[1] = height / ycbcr_format.chroma_subsampling_y;
  83         heights[2] = height / ycbcr_format.chroma_subsampling_y;
  84
  85         pixel_data[0] = pixel_data[1] = pixel_data[2] = NULL;
  86 }
  87
  88 YCbCrInput::~YCbCrInput()
  89 {
  90         for (unsigned channel = 0; channel < 3; ++channel) {
  91                 if (texture_num[channel] != 0) {
  92                         resource_pool->release_2d_texture(texture_num[channel]);
  93                 }
  94         }
  95 }
  96
  97 void YCbCrInput::set_gl_state(GLuint glsl_program_num, const string& prefix, unsigned *sampler_num)
  98 {
  99         for (unsigned channel = 0; channel < 3; ++channel) {
 100                 glActiveTexture(GL_TEXTURE0 + *sampler_num + channel);
 101                 check_error();
 102
 103                 if (texture_num[channel] == 0) {
 104                         // (Re-)upload the texture.
 105                         texture_num[channel] = resource_pool->create_2d_texture(GL_R8, widths[channel], heights[channel]);
 106                         glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
 107                         check_error();
 108                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 109                         check_error();
 110                         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, pbos[channel]);
 111                         check_error();
 112                         glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 113                         check_error();
 114                         glPixelStorei(GL_UNPACK_ROW_LENGTH, pitch[channel]);
 115                         check_error();
 116                         glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, widths[channel], heights[channel], GL_RED, GL_UNSIGNED_BYTE, pixel_data[channel]);
 117                         check_error();
 118                         glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
 119                         check_error();
 120                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 121                         check_error();
 122                         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 123                         check_error();
 124                 } else {
 125                         glBindTexture(GL_TEXTURE_2D, texture_num[channel]);
 126                         check_error();
 127                 }
 128         }
 129
 130         glBindBuffer(GL_PIXEL_UNPACK_BUFFER_ARB, 0);
 131         check_error();
 132
 133         // Bind samplers.
 134         set_uniform_int(glsl_program_num, prefix, "tex_y", *sampler_num + 0);
 135         set_uniform_int(glsl_program_num, prefix, "tex_cb", *sampler_num + 1);
 136         set_uniform_int(glsl_program_num, prefix, "tex_cr", *sampler_num + 2);
 137
 138         *sampler_num += 3;
 139 }
 140
 141 string YCbCrInput::output_fragment_shader()
 142 {
 143         float coeff[3], offset[3];
 144         double scale[3];
 145
 146         switch (ycbcr_format.luma_coefficients) {
 147         case YCBCR_REC_601:
 148                 // Rec. 601, page 2.
 149                 coeff[0] = 0.299;
 150                 coeff[1] = 0.587;
 151                 coeff[2] = 0.114;
 152                 break;
 153
 154         case YCBCR_REC_709:
 155                 // Rec. 709, page 19.
 156                 coeff[0] = 0.2126;
 157                 coeff[1] = 0.7152;
 158                 coeff[2] = 0.0722;
 159                 break;
 160
 161         case YCBCR_REC_2020:
 162                 // Rec. 2020, page 4.
 163                 coeff[0] = 0.2627;
 164                 coeff[1] = 0.6780;
 165                 coeff[2] = 0.0593;
 166                 break;
 167
 168         default:
 169                 assert(false);
 170         }
 171
 172         if (ycbcr_format.full_range) {
 173                 offset[0] = 0.0 / 255.0;
 174                 offset[1] = 128.0 / 255.0;
 175                 offset[2] = 128.0 / 255.0;
 176
 177                 scale[0] = 1.0;
 178                 scale[1] = 1.0;
 179                 scale[2] = 1.0;
 180         } else {
 181                 // Rec. 601, page 4; Rec. 709, page 19; Rec. 2020, page 4.
 182                 offset[0] = 16.0 / 255.0;
 183                 offset[1] = 128.0 / 255.0;
 184                 offset[2] = 128.0 / 255.0;
 185
 186                 scale[0] = 255.0 / 219.0;
 187                 scale[1] = 255.0 / 224.0;
 188                 scale[2] = 255.0 / 224.0;
 189         }
 190
 191         // Matrix to convert RGB to YCbCr. See e.g. Rec. 601.
 192         Matrix3d rgb_to_ycbcr;
 193         rgb_to_ycbcr(0,0) = coeff[0];
 194         rgb_to_ycbcr(0,1) = coeff[1];
 195         rgb_to_ycbcr(0,2) = coeff[2];
 196
 197         float cb_fac = (224.0 / 219.0) / (coeff[0] + coeff[1] + 1.0f - coeff[2]);
 198         rgb_to_ycbcr(1,0) = -coeff[0] * cb_fac;
 199         rgb_to_ycbcr(1,1) = -coeff[1] * cb_fac;
 200         rgb_to_ycbcr(1,2) = (1.0f - coeff[2]) * cb_fac;
 201
 202         float cr_fac = (224.0 / 219.0) / (1.0f - coeff[0] + coeff[1] + coeff[2]);
 203         rgb_to_ycbcr(2,0) = (1.0f - coeff[0]) * cr_fac;
 204         rgb_to_ycbcr(2,1) = -coeff[1] * cr_fac;
 205         rgb_to_ycbcr(2,2) = -coeff[2] * cr_fac;
 206
 207         // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
 208         Matrix3d ycbcr_to_rgb = rgb_to_ycbcr.inverse();
 209
 210         // Fold in the scaling.
 211         ycbcr_to_rgb *= Map<const Vector3d>(scale).asDiagonal();
 212
 213         string frag_shader;
 214
 215         frag_shader = output_glsl_mat3("PREFIX(inv_ycbcr_matrix)", ycbcr_to_rgb);
 216         frag_shader += output_glsl_vec3("PREFIX(offset)", offset[0], offset[1], offset[2]);
 217
 218         float cb_offset_x = compute_chroma_offset(
 219                 ycbcr_format.cb_x_position, ycbcr_format.chroma_subsampling_x, widths[1]);
 220         float cb_offset_y = compute_chroma_offset(
 221                 ycbcr_format.cb_y_position, ycbcr_format.chroma_subsampling_y, heights[1]);
 222         frag_shader += output_glsl_vec2("PREFIX(cb_offset)", cb_offset_x, cb_offset_y);
 223
 224         float cr_offset_x = compute_chroma_offset(
 225                 ycbcr_format.cr_x_position, ycbcr_format.chroma_subsampling_x, widths[2]);
 226         float cr_offset_y = compute_chroma_offset(
 227                 ycbcr_format.cr_y_position, ycbcr_format.chroma_subsampling_y, heights[2]);
 228         frag_shader += output_glsl_vec2("PREFIX(cr_offset)", cr_offset_x, cr_offset_y);
 229
 230         frag_shader += read_file("ycbcr_input.frag");
 231         return frag_shader;
 232 }
 233
 234 void YCbCrInput::invalidate_pixel_data()
 235 {
 236         for (unsigned channel = 0; channel < 3; ++channel) {
 237                 if (texture_num[channel] != 0) {
 238                         resource_pool->release_2d_texture(texture_num[channel]);
 239                         texture_num[channel] = 0;
 240                 }
 241         }
 242 }
 243
 244 bool YCbCrInput::set_int(const std::string& key, int value)
 245 {
 246         if (key == "needs_mipmaps") {
 247                 // We currently do not support this.
 248                 return (value == 0);
 249         }
 250         return Effect::set_int(key, value);
 251 }
 252
 253 }  // namespace movit