git.sesse.net Git - nageru/blob - chroma_subsampler.cpp

   1 #include "chroma_subsampler.h"
   2 #include "v210_converter.h"
   3
   4 #include <vector>
   5
   6 #include <movit/effect_util.h>
   7 #include <movit/resource_pool.h>
   8 #include <movit/util.h>
   9
  10 using namespace movit;
  11 using namespace std;
  12
  13 ChromaSubsampler::ChromaSubsampler(ResourcePool *resource_pool)
  14         : resource_pool(resource_pool)
  15 {
  16         vector<string> frag_shader_outputs;
  17
  18         // Set up stuff for NV12 conversion.
  19         //
  20         // Note: Due to the horizontally co-sited chroma/luma samples in H.264
  21         // (chrome position is left for horizontal and center for vertical),
  22         // we need to be a bit careful in our subsampling. A diagram will make
  23         // this clearer, showing some luma and chroma samples:
  24         //
  25         //     a   b   c   d
  26         //   +---+---+---+---+
  27         //   |   |   |   |   |
  28         //   | Y | Y | Y | Y |
  29         //   |   |   |   |   |
  30         //   +---+---+---+---+
  31         //
  32         // +-------+-------+
  33         // |       |       |
  34         // |   C   |   C   |
  35         // |       |       |
  36         // +-------+-------+
  37         //
  38         // Clearly, the rightmost chroma sample here needs to be equivalent to
  39         // b/4 + c/2 + d/4. (We could also implement more sophisticated filters,
  40         // of course, but as long as the upsampling is not going to be equally
  41         // sophisticated, it's probably not worth it.) If we sample once with
  42         // no mipmapping, we get just c, ie., no actual filtering in the
  43         // horizontal direction. (For the vertical direction, we can just
  44         // sample in the middle to get the right filtering.) One could imagine
  45         // we could use mipmapping (assuming we can create mipmaps cheaply),
  46         // but then, what we'd get is this:
  47         //
  48         //    (a+b)/2 (c+d)/2
  49         //   +-------+-------+
  50         //   |       |       |
  51         //   |   Y   |   Y   |
  52         //   |       |       |
  53         //   +-------+-------+
  54         //
  55         // +-------+-------+
  56         // |       |       |
  57         // |   C   |   C   |
  58         // |       |       |
  59         // +-------+-------+
  60         //
  61         // which ends up sampling equally from a and b, which clearly isn't right. Instead,
  62         // we need to do two (non-mipmapped) chroma samples, both hitting exactly in-between
  63         // source pixels.
  64         //
  65         // Sampling in-between b and c gives us the sample (b+c)/2, and similarly for c and d.
  66         // Taking the average of these gives of (b+c)/4 + (c+d)/4 = b/4 + c/2 + d/4, which is
  67         // exactly what we want.
  68         //
  69         // See also http://www.poynton.com/PDFs/Merging_RGB_and_422.pdf, pages 6–7.
  70
  71         // Cb/Cr shader.
  72         string cbcr_vert_shader =
  73                 "#version 130 \n"
  74                 " \n"
  75                 "in vec2 position; \n"
  76                 "in vec2 texcoord; \n"
  77                 "out vec2 tc0, tc1; \n"
  78                 "uniform vec2 foo_chroma_offset_0; \n"
  79                 "uniform vec2 foo_chroma_offset_1; \n"
  80                 " \n"
  81                 "void main() \n"
  82                 "{ \n"
  83                 "    // The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is: \n"
  84                 "    // \n"
  85                 "    //   2.000  0.000  0.000 -1.000 \n"
  86                 "    //   0.000  2.000  0.000 -1.000 \n"
  87                 "    //   0.000  0.000 -2.000 -1.000 \n"
  88                 "    //   0.000  0.000  0.000  1.000 \n"
  89                 "    gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0); \n"
  90                 "    vec2 flipped_tc = texcoord; \n"
  91                 "    tc0 = flipped_tc + foo_chroma_offset_0; \n"
  92                 "    tc1 = flipped_tc + foo_chroma_offset_1; \n"
  93                 "} \n";
  94         string cbcr_frag_shader =
  95                 "#version 130 \n"
  96                 "in vec2 tc0, tc1; \n"
  97                 "uniform sampler2D cbcr_tex; \n"
  98                 "out vec4 FragColor, FragColor2; \n"
  99                 "void main() { \n"
 100                 "    FragColor = 0.5 * (texture(cbcr_tex, tc0) + texture(cbcr_tex, tc1)); \n"
 101                 "    FragColor2 = FragColor; \n"
 102                 "} \n";
 103         cbcr_program_num = resource_pool->compile_glsl_program(cbcr_vert_shader, cbcr_frag_shader, frag_shader_outputs);
 104         check_error();
 105         cbcr_chroma_offset_0_location = get_uniform_location(cbcr_program_num, "foo", "chroma_offset_0");
 106         check_error();
 107         cbcr_chroma_offset_1_location = get_uniform_location(cbcr_program_num, "foo", "chroma_offset_1");
 108         check_error();
 109
 110         cbcr_texture_sampler_uniform = glGetUniformLocation(cbcr_program_num, "cbcr_tex");
 111         check_error();
 112         cbcr_position_attribute_index = glGetAttribLocation(cbcr_program_num, "position");
 113         check_error();
 114         cbcr_texcoord_attribute_index = glGetAttribLocation(cbcr_program_num, "texcoord");
 115         check_error();
 116
 117         // Same, for UYVY conversion.
 118         string uyvy_vert_shader =
 119                 "#version 130 \n"
 120                 " \n"
 121                 "in vec2 position; \n"
 122                 "in vec2 texcoord; \n"
 123                 "out vec2 y_tc0, y_tc1, cbcr_tc0, cbcr_tc1; \n"
 124                 "uniform vec2 foo_luma_offset_0; \n"
 125                 "uniform vec2 foo_luma_offset_1; \n"
 126                 "uniform vec2 foo_chroma_offset_0; \n"
 127                 "uniform vec2 foo_chroma_offset_1; \n"
 128                 " \n"
 129                 "void main() \n"
 130                 "{ \n"
 131                 "    // The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is: \n"
 132                 "    // \n"
 133                 "    //   2.000  0.000  0.000 -1.000 \n"
 134                 "    //   0.000  2.000  0.000 -1.000 \n"
 135                 "    //   0.000  0.000 -2.000 -1.000 \n"
 136                 "    //   0.000  0.000  0.000  1.000 \n"
 137                 "    gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0); \n"
 138                 "    vec2 flipped_tc = texcoord; \n"
 139                 "    y_tc0 = flipped_tc + foo_luma_offset_0; \n"
 140                 "    y_tc1 = flipped_tc + foo_luma_offset_1; \n"
 141                 "    cbcr_tc0 = flipped_tc + foo_chroma_offset_0; \n"
 142                 "    cbcr_tc1 = flipped_tc + foo_chroma_offset_1; \n"
 143                 "} \n";
 144         string uyvy_frag_shader =
 145                 "#version 130 \n"
 146                 "in vec2 y_tc0, y_tc1, cbcr_tc0, cbcr_tc1; \n"
 147                 "uniform sampler2D y_tex, cbcr_tex; \n"
 148                 "out vec4 FragColor; \n"
 149                 "void main() { \n"
 150                 "    float y0 = texture(y_tex, y_tc0).r; \n"
 151                 "    float y1 = texture(y_tex, y_tc1).r; \n"
 152                 "    vec2 cbcr0 = texture(cbcr_tex, cbcr_tc0).rg; \n"
 153                 "    vec2 cbcr1 = texture(cbcr_tex, cbcr_tc1).rg; \n"
 154                 "    vec2 cbcr = 0.5 * (cbcr0 + cbcr1); \n"
 155                 "    FragColor = vec4(cbcr.g, y0, cbcr.r, y1); \n"
 156                 "} \n";
 157
 158         uyvy_program_num = resource_pool->compile_glsl_program(uyvy_vert_shader, uyvy_frag_shader, frag_shader_outputs);
 159         check_error();
 160         uyvy_luma_offset_0_location = get_uniform_location(uyvy_program_num, "foo", "luma_offset_0");
 161         check_error();
 162         uyvy_luma_offset_1_location = get_uniform_location(uyvy_program_num, "foo", "luma_offset_1");
 163         check_error();
 164         uyvy_chroma_offset_0_location = get_uniform_location(uyvy_program_num, "foo", "chroma_offset_0");
 165         check_error();
 166         uyvy_chroma_offset_1_location = get_uniform_location(uyvy_program_num, "foo", "chroma_offset_1");
 167         check_error();
 168
 169         uyvy_y_texture_sampler_uniform = glGetUniformLocation(uyvy_program_num, "y_tex");
 170         check_error();
 171         uyvy_cbcr_texture_sampler_uniform = glGetUniformLocation(uyvy_program_num, "cbcr_tex");
 172         check_error();
 173         uyvy_position_attribute_index = glGetAttribLocation(uyvy_program_num, "position");
 174         check_error();
 175         uyvy_texcoord_attribute_index = glGetAttribLocation(uyvy_program_num, "texcoord");
 176         check_error();
 177
 178         // Shared between the two.
 179         float vertices[] = {
 180                 0.0f, 2.0f,
 181                 0.0f, 0.0f,
 182                 2.0f, 0.0f
 183         };
 184         vbo = generate_vbo(2, GL_FLOAT, sizeof(vertices), vertices);
 185         check_error();
 186
 187         // v210 compute shader.
 188         if (v210Converter::has_hardware_support()) {
 189                 string v210_shader_src = R"(#version 150
 190 #extension GL_ARB_compute_shader : enable
 191 #extension GL_ARB_shader_image_load_store : enable
 192 layout(local_size_x=2, local_size_y=16) in;
 193 layout(r16) uniform restrict readonly image2D in_y;
 194 uniform sampler2D in_cbcr;  // Of type RG16.
 195 layout(rgb10_a2) uniform restrict writeonly image2D outbuf;
 196 uniform float inv_width, inv_height;
 197
 198 void main()
 199 {
 200         int xb = int(gl_GlobalInvocationID.x);  // X block number.
 201         int y = int(gl_GlobalInvocationID.y);  // Y (actual line).
 202         float yf = (gl_GlobalInvocationID.y + 0.5f) * inv_height;  // Y float coordinate.
 203
 204         // Load and scale CbCr values, sampling in-between the texels to get
 205         // to (left/4 + center/2 + right/4).
 206         vec2 pix_cbcr[3];
 207         for (int i = 0; i < 3; ++i) {
 208                 vec2 a = texture(in_cbcr, vec2((xb * 6 + i * 2) * inv_width, yf)).xy;
 209                 vec2 b = texture(in_cbcr, vec2((xb * 6 + i * 2 + 1) * inv_width, yf)).xy;
 210                 pix_cbcr[i] = (a + b) * (0.5 * 65535.0 / 1023.0);
 211         }
 212
 213         // Load and scale the Y values. Note that we use integer coordinates here,
 214         // so we don't need to offset by 0.5.
 215         float pix_y[6];
 216         for (int i = 0; i < 6; ++i) {
 217                 pix_y[i] = imageLoad(in_y, ivec2(xb * 6 + i, y)).x * (65535.0 / 1023.0);
 218         }
 219
 220         imageStore(outbuf, ivec2(xb * 4 + 0, y), vec4(pix_cbcr[0].x, pix_y[0],      pix_cbcr[0].y, 1.0));
 221         imageStore(outbuf, ivec2(xb * 4 + 1, y), vec4(pix_y[1],      pix_cbcr[1].x, pix_y[2],      1.0));
 222         imageStore(outbuf, ivec2(xb * 4 + 2, y), vec4(pix_cbcr[1].y, pix_y[3],      pix_cbcr[2].x, 1.0));
 223         imageStore(outbuf, ivec2(xb * 4 + 3, y), vec4(pix_y[4],      pix_cbcr[2].y, pix_y[5],      1.0));
 224 }
 225 )";
 226                 GLuint shader_num = movit::compile_shader(v210_shader_src, GL_COMPUTE_SHADER);
 227                 check_error();
 228                 v210_program_num = glCreateProgram();
 229                 check_error();
 230                 glAttachShader(v210_program_num, shader_num);
 231                 check_error();
 232                 glLinkProgram(v210_program_num);
 233                 check_error();
 234
 235                 GLint success;
 236                 glGetProgramiv(v210_program_num, GL_LINK_STATUS, &success);
 237                 check_error();
 238                 if (success == GL_FALSE) {
 239                         GLchar error_log[1024] = {0};
 240                         glGetProgramInfoLog(v210_program_num, 1024, nullptr, error_log);
 241                         fprintf(stderr, "Error linking program: %s\n", error_log);
 242                         exit(1);
 243                 }
 244
 245                 v210_in_y_pos = glGetUniformLocation(v210_program_num, "in_y");
 246                 check_error();
 247                 v210_in_cbcr_pos = glGetUniformLocation(v210_program_num, "in_cbcr");
 248                 check_error();
 249                 v210_outbuf_pos = glGetUniformLocation(v210_program_num, "outbuf");
 250                 check_error();
 251                 v210_inv_width_pos = glGetUniformLocation(v210_program_num, "inv_width");
 252                 check_error();
 253                 v210_inv_height_pos = glGetUniformLocation(v210_program_num, "inv_height");
 254                 check_error();
 255         } else {
 256                 v210_program_num = 0;
 257         }
 258 }
 259
 260 ChromaSubsampler::~ChromaSubsampler()
 261 {
 262         resource_pool->release_glsl_program(cbcr_program_num);
 263         check_error();
 264         resource_pool->release_glsl_program(uyvy_program_num);
 265         check_error();
 266         glDeleteBuffers(1, &vbo);
 267         check_error();
 268         if (v210_program_num != 0) {
 269                 glDeleteProgram(v210_program_num);
 270                 check_error();
 271         }
 272 }
 273
 274 void ChromaSubsampler::subsample_chroma(GLuint cbcr_tex, unsigned width, unsigned height, GLuint dst_tex, GLuint dst2_tex)
 275 {
 276         GLuint vao = resource_pool->create_vec2_vao({ cbcr_position_attribute_index, cbcr_texcoord_attribute_index }, vbo);
 277         glBindVertexArray(vao);
 278         check_error();
 279
 280         // Extract Cb/Cr.
 281         GLuint fbo;
 282         if (dst2_tex <= 0) {
 283                 fbo = resource_pool->create_fbo(dst_tex);
 284         } else {
 285                 fbo = resource_pool->create_fbo(dst_tex, dst2_tex);
 286         }
 287         glBindFramebuffer(GL_FRAMEBUFFER, fbo);
 288         glViewport(0, 0, width/2, height/2);
 289         check_error();
 290
 291         glUseProgram(cbcr_program_num);
 292         check_error();
 293
 294         glActiveTexture(GL_TEXTURE0);
 295         check_error();
 296         glBindTexture(GL_TEXTURE_2D, cbcr_tex);
 297         check_error();
 298         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 299         check_error();
 300         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 301         check_error();
 302         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 303         check_error();
 304
 305         glUniform2f(cbcr_chroma_offset_0_location, -1.0f / width, 0.0f);
 306         check_error();
 307         glUniform2f(cbcr_chroma_offset_1_location, -0.0f / width, 0.0f);
 308         check_error();
 309         glUniform1i(cbcr_texture_sampler_uniform, 0);
 310
 311         glDrawArrays(GL_TRIANGLES, 0, 3);
 312         check_error();
 313
 314         glUseProgram(0);
 315         check_error();
 316         glBindFramebuffer(GL_FRAMEBUFFER, 0);
 317         check_error();
 318         glBindVertexArray(0);
 319         check_error();
 320
 321         resource_pool->release_fbo(fbo);
 322         resource_pool->release_vec2_vao(vao);
 323 }
 324
 325 void ChromaSubsampler::create_uyvy(GLuint y_tex, GLuint cbcr_tex, unsigned width, unsigned height, GLuint dst_tex)
 326 {
 327         GLuint vao = resource_pool->create_vec2_vao({ cbcr_position_attribute_index, cbcr_texcoord_attribute_index }, vbo);
 328         glBindVertexArray(vao);
 329         check_error();
 330
 331         glBindVertexArray(vao);
 332         check_error();
 333
 334         GLuint fbo = resource_pool->create_fbo(dst_tex);
 335         glBindFramebuffer(GL_FRAMEBUFFER, fbo);
 336         glViewport(0, 0, width/2, height);
 337         check_error();
 338
 339         glUseProgram(uyvy_program_num);
 340         check_error();
 341
 342         glUniform1i(uyvy_y_texture_sampler_uniform, 0);
 343         check_error();
 344         glUniform1i(uyvy_cbcr_texture_sampler_uniform, 1);
 345         check_error();
 346
 347         glActiveTexture(GL_TEXTURE0);
 348         check_error();
 349         glBindTexture(GL_TEXTURE_2D, y_tex);
 350         check_error();
 351         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 352         check_error();
 353         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 354         check_error();
 355         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 356         check_error();
 357
 358         glActiveTexture(GL_TEXTURE1);
 359         check_error();
 360         glBindTexture(GL_TEXTURE_2D, cbcr_tex);
 361         check_error();
 362         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 363         check_error();
 364         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 365         check_error();
 366         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 367         check_error();
 368
 369         glUniform2f(uyvy_luma_offset_0_location, -0.5f / width, 0.0f);
 370         check_error();
 371         glUniform2f(uyvy_luma_offset_1_location,  0.5f / width, 0.0f);
 372         check_error();
 373         glUniform2f(uyvy_chroma_offset_0_location, -1.0f / width, 0.0f);
 374         check_error();
 375         glUniform2f(uyvy_chroma_offset_1_location, -0.0f / width, 0.0f);
 376         check_error();
 377
 378         glBindBuffer(GL_ARRAY_BUFFER, vbo);
 379         check_error();
 380
 381         glDrawArrays(GL_TRIANGLES, 0, 3);
 382         check_error();
 383
 384         glActiveTexture(GL_TEXTURE0);
 385         check_error();
 386         glUseProgram(0);
 387         check_error();
 388         glBindFramebuffer(GL_FRAMEBUFFER, 0);
 389         check_error();
 390         glBindVertexArray(0);
 391         check_error();
 392
 393         resource_pool->release_fbo(fbo);
 394         resource_pool->release_vec2_vao(vao);
 395 }
 396
 397 void ChromaSubsampler::create_v210(GLuint y_tex, GLuint cbcr_tex, unsigned width, unsigned height, GLuint dst_tex)
 398 {
 399         assert(v210_program_num != 0);
 400
 401         glUseProgram(v210_program_num);
 402         check_error();
 403
 404         glUniform1i(v210_in_y_pos, 0);
 405         check_error();
 406         glUniform1i(v210_in_cbcr_pos, 1);
 407         check_error();
 408         glUniform1i(v210_outbuf_pos, 2);
 409         check_error();
 410         glUniform1f(v210_inv_width_pos, 1.0 / width);
 411         check_error();
 412         glUniform1f(v210_inv_height_pos, 1.0 / height);
 413         check_error();
 414
 415         glActiveTexture(GL_TEXTURE0);
 416         check_error();
 417         glBindTexture(GL_TEXTURE_2D, y_tex);  // We don't actually need to bind it, but we need to set the state.
 418         check_error();
 419         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 420         check_error();
 421         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 422         check_error();
 423         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 424         check_error();
 425         glBindImageTexture(0, y_tex, 0, GL_FALSE, 0, GL_READ_ONLY, GL_R16);  // This is the real bind.
 426         check_error();
 427
 428         glActiveTexture(GL_TEXTURE1);
 429         check_error();
 430         glBindTexture(GL_TEXTURE_2D, cbcr_tex);
 431         check_error();
 432         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 433         check_error();
 434         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 435         check_error();
 436         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 437         check_error();
 438
 439         glBindImageTexture(2, dst_tex, 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RGB10_A2);
 440         check_error();
 441
 442         // Actually run the shader. We use workgroups of size 2x16 threadst , and each thread
 443         // processes 6x1 input pixels, so round up to number of 12x16 pixel blocks.
 444         glDispatchCompute((width + 11) / 12, (height + 15) / 16, 1);
 445
 446         glBindTexture(GL_TEXTURE_2D, 0);
 447         check_error();
 448         glActiveTexture(GL_TEXTURE0);
 449         check_error();
 450         glUseProgram(0);
 451         check_error();
 452 }