git.sesse.net Git - pkanalytics/blob - video_widget.cpp

   1 #define GL_GLEXT_PROTOTYPES
   2
   3 #include "video_widget.h"
   4
   5 #include <assert.h>
   6 #include <pthread.h>
   7 #include <stdint.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <sys/stat.h>
  12 #include <unistd.h>
  13
  14 extern "C" {
  15 #include <libavcodec/avcodec.h>
  16 #include <libavformat/avformat.h>
  17 #include <libavutil/avutil.h>
  18 #include <libavutil/error.h>
  19 #include <libavutil/frame.h>
  20 #include <libavutil/imgutils.h>
  21 #include <libavutil/mem.h>
  22 #include <libavutil/pixfmt.h>
  23 #include <libavutil/opt.h>
  24 #include <libswscale/swscale.h>
  25 }
  26
  27 #include <chrono>
  28 #include <cstdint>
  29 #include <utility>
  30 #include <vector>
  31 #include <unordered_set>
  32
  33 #include "post_to_main_thread.h"
  34
  35 #include <QOpenGLFunctions>
  36 #include <QWheelEvent>
  37 #include <QMouseEvent>
  38
  39 using namespace std;
  40 using namespace std::chrono;
  41
  42 namespace {
  43
  44 bool is_full_range(const AVPixFmtDescriptor *desc)
  45 {
  46         // This is horrible, but there's no better way that I know of.
  47         return (strchr(desc->name, 'j') != nullptr);
  48 }
  49
  50 AVPixelFormat decide_dst_format(AVPixelFormat src_format)
  51 {
  52         // If this is a non-Y'CbCr format, just convert to 4:4:4 Y'CbCr
  53         // and be done with it. It's too strange to spend a lot of time on.
  54         // (Let's hope there's no alpha.)
  55         const AVPixFmtDescriptor *src_desc = av_pix_fmt_desc_get(src_format);
  56         if (src_desc == nullptr ||
  57             src_desc->nb_components != 3 ||
  58             (src_desc->flags & AV_PIX_FMT_FLAG_RGB)) {
  59                 return AV_PIX_FMT_YUV444P;
  60         }
  61
  62         // The best for us would be Cb and Cr together if possible,
  63         // but FFmpeg doesn't support that except in the special case of
  64         // NV12, so we need to go to planar even for the case of NV12.
  65         // Thus, look for the closest (but no worse) 8-bit planar Y'CbCr format
  66         // that matches in color range. (This will also include the case of
  67         // the source format already being acceptable.)
  68         bool src_full_range = is_full_range(src_desc);
  69         const char *best_format = "yuv444p";
  70         unsigned best_score = numeric_limits<unsigned>::max();
  71         for (const AVPixFmtDescriptor *desc = av_pix_fmt_desc_next(nullptr);
  72              desc;
  73              desc = av_pix_fmt_desc_next(desc)) {
  74                 // Find planar Y'CbCr formats only.
  75                 if (desc->nb_components != 3) continue;
  76                 if (desc->flags & AV_PIX_FMT_FLAG_RGB) continue;
  77                 if (!(desc->flags & AV_PIX_FMT_FLAG_PLANAR)) continue;
  78                 if (desc->comp[0].plane != 0 ||
  79                     desc->comp[1].plane != 1 ||
  80                     desc->comp[2].plane != 2) continue;
  81
  82                 // 8-bit formats only.
  83                 if (desc->flags & AV_PIX_FMT_FLAG_BE) continue;
  84                 if (desc->comp[0].depth != 8) continue;
  85
  86                 // Same or better chroma resolution only.
  87                 int chroma_w_diff = src_desc->log2_chroma_w - desc->log2_chroma_w;
  88                 int chroma_h_diff = src_desc->log2_chroma_h - desc->log2_chroma_h;
  89                 if (chroma_w_diff < 0 || chroma_h_diff < 0)
  90                         continue;
  91
  92                 // Matching full/limited range only.
  93                 if (is_full_range(desc) != src_full_range)
  94                         continue;
  95
  96                 // Pick something with as little excess chroma resolution as possible.
  97                 unsigned score = (1 << (chroma_w_diff)) << chroma_h_diff;
  98                 if (score < best_score) {
  99                         best_score = score;
 100                         best_format = desc->name;
 101                 }
 102         }
 103         return av_get_pix_fmt(best_format);
 104 }
 105
 106 }  // namespace
 107
 108 bool VideoWidget::process_queued_commands(AVFormatContext *format_ctx, AVCodecContext *video_codec_ctx, int video_stream_index, bool *seeked)
 109 {
 110         // Process any queued commands from other threads.
 111         vector<QueuedCommand> commands;
 112         {
 113                 lock_guard<mutex> lock(queue_mu);
 114                 swap(commands, command_queue);
 115         }
 116
 117         for (const QueuedCommand &cmd : commands) {
 118                 switch (cmd.command) {
 119                 case QueuedCommand::PAUSE:
 120                         paused = true;
 121                         break;
 122                 case QueuedCommand::RESUME:
 123                         paused = false;
 124                         pts_origin = last_pts;
 125                         start = next_frame_start = steady_clock::now();
 126                         break;
 127                 case QueuedCommand::SEEK:
 128                 case QueuedCommand::SEEK_ABSOLUTE:
 129                         // Dealt with below.
 130                         break;
 131                 }
 132         }
 133
 134         // Combine all seeks into one big one. (There are edge cases where this is probably
 135         // subtly wrong, but we'll live with it.)
 136         int64_t base_pts = last_pts;
 137         int64_t relative_seek_ms = 0;
 138         int64_t relative_seek_frames = 0;
 139         for (const QueuedCommand &cmd : commands) {
 140                 if (cmd.command == QueuedCommand::SEEK) {
 141                         relative_seek_ms += cmd.relative_seek_ms;
 142                         relative_seek_frames += cmd.relative_seek_frames;
 143                 } else if (cmd.command == QueuedCommand::SEEK_ABSOLUTE) {
 144                         base_pts = av_rescale_q(cmd.seek_ms, AVRational{ 1, 1000 }, video_timebase);
 145                         relative_seek_ms = 0;
 146                         relative_seek_frames = 0;
 147                 }
 148         }
 149         int64_t relative_seek_pts = av_rescale_q(relative_seek_ms, AVRational{ 1, 1000 }, video_timebase);
 150         if (relative_seek_ms != 0 && relative_seek_pts == 0) {
 151                 // Just to be sure rounding errors don't move us into nothingness.
 152                 relative_seek_pts = (relative_seek_ms > 0) ? 1 : -1;
 153         }
 154         int64_t goal_pts = base_pts + relative_seek_pts;
 155         if (goal_pts != last_pts || relative_seek_frames < 0) {
 156                 avcodec_flush_buffers(video_codec_ctx);
 157                 queued_frames.clear();
 158
 159                 // Seek to the last keyframe before this point.
 160                 int64_t seek_pts = goal_pts;
 161                 if (relative_seek_frames < 0) {
 162                         // If we're frame-skipping backwards, add 100 ms of slop for each frame
 163                         // so we're fairly certain we are able to see the ones we want.
 164                         seek_pts -= av_rescale_q(-relative_seek_frames, AVRational{ 1, 10 }, video_timebase);
 165                 }
 166                 av_seek_frame(format_ctx, video_stream_index, seek_pts, AVSEEK_FLAG_BACKWARD);
 167
 168                 // Decode frames until EOF, or until we see something past our seek point.
 169                 std::deque<AVFrameWithDeleter> queue;
 170                 for ( ;; ) {
 171                         bool error = false;
 172                         AVFrameWithDeleter frame = decode_frame(format_ctx, video_codec_ctx,
 173                                 pathname, video_stream_index, &error);
 174                         if (frame == nullptr || error) {
 175                                 break;
 176                         }
 177
 178                         int64_t frame_pts = frame->pts;
 179                         if (relative_seek_frames < 0) {
 180                                 // Buffer this frame; don't display it unless we know it's the Nth-latest.
 181                                 queue.push_back(std::move(frame));
 182                                 if (queue.size() > uint64_t(-relative_seek_frames) + 1) {
 183                                         queue.pop_front();
 184                                 }
 185                         }
 186                         if (frame_pts >= goal_pts) {
 187                                 if (relative_seek_frames > 0) {
 188                                         --relative_seek_frames;
 189                                 } else {
 190                                         if (relative_seek_frames < 0) {
 191                                                 // Hope we have the right amount.
 192                                                 // The rest will remain in the queue for when we play forward again.
 193                                                 frame = std::move(queue.front());
 194                                                 queue.pop_front();
 195                                                 queued_frames = std::move(queue);
 196                                         }
 197                                         Frame *new_frame = new Frame(make_video_frame(frame.get()));
 198                                         {
 199                                                 lock_guard lock(current_frame_mu);
 200                                                 current_frame.reset(new_frame);
 201                                         }
 202                                         update();
 203                                         store_pts(frame->pts);
 204                                         break;
 205                                 }
 206                         }
 207                 }
 208
 209                 // NOTE: We keep pause status as-is.
 210
 211                 pts_origin = last_pts;
 212                 start = next_frame_start = last_frame = steady_clock::now();
 213                 if (seeked) {
 214                         *seeked = true;
 215                 }
 216         } else if (relative_seek_frames > 0) {
 217                 // The base PTS is fine, we only need to skip a few frames forwards.
 218                 while (relative_seek_frames > 1) {
 219                         // Eat a frame (ignore errors).
 220                         bool error;
 221                         decode_frame(format_ctx, video_codec_ctx, pathname, video_stream_index, &error);
 222                         --relative_seek_frames;
 223                 }
 224
 225                 // Display the last one.
 226                 bool error;
 227                 AVFrameWithDeleter frame = decode_frame(format_ctx, video_codec_ctx,
 228                         pathname, video_stream_index, &error);
 229                 if (frame == nullptr || error) {
 230                         return true;
 231                 }
 232                 Frame *new_frame = new Frame(make_video_frame(frame.get()));
 233                 {
 234                         lock_guard lock(current_frame_mu);
 235                         current_frame.reset(new_frame);
 236                 }
 237                 update();
 238                 store_pts(frame->pts);
 239         }
 240         return false;
 241 }
 242
 243 VideoWidget::VideoWidget(QWidget *parent)
 244         : QOpenGLWidget(parent) {}
 245
 246 GLuint compile_shader(const string &shader_src, GLenum type)
 247 {
 248         GLuint obj = glCreateShader(type);
 249         const GLchar* source[] = { shader_src.data() };
 250         const GLint length[] = { (GLint)shader_src.size() };
 251         glShaderSource(obj, 1, source, length);
 252         glCompileShader(obj);
 253
 254         GLchar info_log[4096];
 255         GLsizei log_length = sizeof(info_log) - 1;
 256         glGetShaderInfoLog(obj, log_length, &log_length, info_log);
 257         info_log[log_length] = 0;
 258         if (strlen(info_log) > 0) {
 259                 fprintf(stderr, "Shader compile log: %s\n", info_log);
 260         }
 261
 262         GLint status;
 263         glGetShaderiv(obj, GL_COMPILE_STATUS, &status);
 264         if (status == GL_FALSE) {
 265                 // Add some line numbers to easier identify compile errors.
 266                 string src_with_lines = "/*   1 */ ";
 267                 size_t lineno = 1;
 268                 for (char ch : shader_src) {
 269                         src_with_lines.push_back(ch);
 270                         if (ch == '\n') {
 271                                 char buf[32];
 272                                 snprintf(buf, sizeof(buf), "/* %3zu */ ", ++lineno);
 273                                 src_with_lines += buf;
 274                         }
 275                 }
 276
 277                 fprintf(stderr, "Failed to compile shader:\n%s\n", src_with_lines.c_str());
 278                 exit(1);
 279         }
 280
 281         return obj;
 282 }
 283
 284 void VideoWidget::initializeGL()
 285 {
 286         glDisable(GL_BLEND);
 287         glDisable(GL_DEPTH_TEST);
 288         glDepthMask(GL_FALSE);
 289         glCreateTextures(GL_TEXTURE_2D, 3, tex);
 290
 291         ycbcr_vertex_shader = compile_shader(R"(
 292 #version 460 core
 293
 294 layout(location = 0) in vec2 position;
 295 layout(location = 1) in vec2 texcoord;
 296 out vec2 tc;
 297
 298 void main()
 299 {
 300         // The result of glOrtho(0.0, 1.0, 0.0, 1.0, 0.0, 1.0) is:
 301         //
 302         //   2.000  0.000  0.000 -1.000
 303         //   0.000  2.000  0.000 -1.000
 304         //   0.000  0.000 -2.000 -1.000
 305         //   0.000  0.000  0.000  1.000
 306         gl_Position = vec4(2.0 * position.x - 1.0, 2.0 * position.y - 1.0, -1.0, 1.0);
 307         tc = texcoord;
 308         tc.y = 1.0f - tc.y;
 309 }
 310 )", GL_VERTEX_SHADER);
 311         ycbcr_fragment_shader = compile_shader(R"(
 312 #version 460 core
 313
 314 layout(location = 0) uniform sampler2D tex_y;
 315 layout(location = 1) uniform sampler2D tex_cb;
 316 layout(location = 2) uniform sampler2D tex_cr;
 317 layout(location = 3) uniform vec2 cbcr_offset;
 318
 319 in vec2 tc;
 320 out vec4 FragColor;
 321
 322 // Computed statically by Movit, for limited-range BT.709.
 323 // (We don't check whether the input could be BT.601 or BT.2020 currently, or full-range)
 324 const mat3 inv_ycbcr_matrix = mat3(
 325         1.16438f, 1.16438f, 1.16438f,
 326         0.0f, -0.21325f, 2.11240f,
 327         1.79274f, -0.53291f, 0.0f
 328 );
 329
 330 void main()
 331 {
 332         if (tc.x < 0.0 || tc.x > 1.0 || tc.y < 0.0 || tc.y > 1.0) {
 333                 FragColor.rgba = vec4(0.0f, 0.0f, 0.0f, 1.0f);
 334                 return;
 335         }
 336
 337         vec3 ycbcr;
 338         ycbcr.r = texture(tex_y, tc).r;
 339         ycbcr.g = texture(tex_cb, tc + cbcr_offset).r;
 340         ycbcr.b = texture(tex_cr, tc + cbcr_offset).r;
 341         ycbcr -= vec3(16.0f / 255.0f, 128.0f / 255.0f, 128.0f / 255.0f);
 342         FragColor.rgb = inv_ycbcr_matrix * ycbcr;
 343         FragColor.a = 1.0f;
 344 }
 345 )", GL_FRAGMENT_SHADER);
 346         ycbcr_program = glCreateProgram();
 347         glAttachShader(ycbcr_program, ycbcr_vertex_shader);
 348         glAttachShader(ycbcr_program, ycbcr_fragment_shader);
 349         glLinkProgram(ycbcr_program);
 350
 351         GLint success;
 352         glGetProgramiv(ycbcr_program, GL_LINK_STATUS, &success);
 353         if (success == GL_FALSE) {
 354                 GLchar error_log[1024] = {0};
 355                 glGetProgramInfoLog(ycbcr_program, 1024, nullptr, error_log);
 356                 fprintf(stderr, "Error linking program: %s\n", error_log);
 357                 exit(1);
 358         }
 359
 360         glCreateSamplers(1, &bilinear_sampler);
 361         glSamplerParameteri(bilinear_sampler, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
 362         glSamplerParameteri(bilinear_sampler, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 363         glSamplerParameteri(bilinear_sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 364         glSamplerParameteri(bilinear_sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 365 }
 366
 367 void VideoWidget::resizeGL(int w, int h)
 368 {
 369         glViewport(0, 0, w, h);
 370         display_aspect = double(w) / h;
 371 }
 372
 373 int num_levels(GLuint width, GLuint height)
 374 {
 375         int levels = 1;
 376         while (width > 1 || height > 1) {
 377                 width = max(width / 2, 1u);
 378                 height = max(height / 2, 1u);
 379                 ++levels;
 380         }
 381         return levels;
 382 }
 383
 384 void VideoWidget::paintGL()
 385 {
 386         std::shared_ptr<Frame> frame;
 387         {
 388                 lock_guard lock(current_frame_mu);
 389                 frame = current_frame;
 390         }
 391         if (frame == nullptr) {
 392                 glClear(GL_COLOR_BUFFER_BIT);
 393                 return;
 394         }
 395
 396         glUseProgram(ycbcr_program);
 397         if (frame->width != last_width || frame->height != last_height) {
 398                 glTextureStorage2D(tex[0], num_levels(frame->width, frame->height), GL_R8, frame->width, frame->height);
 399         }
 400         if (frame->chroma_width != last_chroma_width || frame->chroma_height != last_chroma_height) {
 401                 for (GLuint num : { tex[1], tex[2] }) {
 402                         glTextureStorage2D(num, num_levels(frame->chroma_width, frame->chroma_height), GL_R8, frame->chroma_width, frame->chroma_height);
 403                 }
 404         }
 405
 406         glTextureSubImage2D(tex[0], 0, 0, 0, frame->width, frame->height, GL_RED, GL_UNSIGNED_BYTE, frame->data.get());
 407         glGenerateTextureMipmap(tex[0]);
 408
 409         glTextureSubImage2D(tex[1], 0, 0, 0, frame->chroma_width, frame->chroma_height, GL_RED, GL_UNSIGNED_BYTE, frame->data.get() + frame->width * frame->height);
 410         glGenerateTextureMipmap(tex[1]);
 411
 412         glTextureSubImage2D(tex[2], 0, 0, 0, frame->chroma_width, frame->chroma_height, GL_RED, GL_UNSIGNED_BYTE, frame->data.get() + frame->width * frame->height + frame->chroma_width * frame->chroma_height);
 413         glGenerateTextureMipmap(tex[2]);
 414
 415         glBindTextureUnit(0, tex[0]);
 416         glBindTextureUnit(1, tex[1]);
 417         glBindTextureUnit(2, tex[2]);
 418         glBindSampler(0, bilinear_sampler);
 419         glBindSampler(1, bilinear_sampler);
 420         glBindSampler(2, bilinear_sampler);
 421         glProgramUniform1i(ycbcr_program, 0, 0);
 422         glProgramUniform1i(ycbcr_program, 1, 1);
 423         glProgramUniform1i(ycbcr_program, 2, 2);
 424         glProgramUniform2f(ycbcr_program, 3, cbcr_offset[0], -cbcr_offset[1]);
 425
 426         float tx1 = 0.0f;
 427         float tx2 = 1.0f;
 428         float ty1 = 0.0f;
 429         float ty2 = 1.0f;
 430
 431         double video_aspect = double(frame->width) / frame->height;
 432         if (display_aspect > video_aspect) {
 433                 double extra_width = frame->height * display_aspect - frame->width;
 434                 tx1 = -0.5 * extra_width / frame->width;
 435                 tx2 = 1.0 + 0.5 * extra_width / frame->width;
 436         } else if (display_aspect < video_aspect) {
 437                 double extra_height = frame->width / display_aspect - frame->height;
 438                 ty1 = -0.5 * extra_height / frame->height;
 439                 ty2 = 1.0 + 0.5 * extra_height / frame->height;
 440         }
 441
 442         glBegin(GL_QUADS);
 443
 444         // (0,0)
 445         glVertexAttrib2f(1, tx1, ty1);
 446         glVertex2f(zoom_matrix[2 * 3 + 0], zoom_matrix[2 * 3 + 1]);
 447
 448         // (0,1)
 449         glVertexAttrib2f(1, tx1, ty2);
 450         glVertex2f(zoom_matrix[1 * 3 + 0] + zoom_matrix[2 * 3 + 0], zoom_matrix[1 * 3 + 1] + zoom_matrix[2 * 3 + 1]);
 451
 452         // (1,1)
 453         glVertexAttrib2f(1, tx2, ty2);
 454         glVertex2f(zoom_matrix[0 * 3 + 0] + zoom_matrix[1 * 3 + 0] + zoom_matrix[2 * 3 + 0],
 455                    zoom_matrix[1 * 3 + 0] + zoom_matrix[1 * 3 + 1] + zoom_matrix[2 * 3 + 1]);
 456
 457         // (1,0)
 458         glVertexAttrib2f(1, tx2, ty1);
 459         glVertex2f(zoom_matrix[0 * 3 + 0] + zoom_matrix[2 * 3 + 0],
 460                    zoom_matrix[1 * 3 + 0] + zoom_matrix[2 * 3 + 1]);
 461
 462         glEnd();
 463 }
 464
 465 void matmul3x3(const double a[9], const double b[9], double res[9])
 466 {
 467         for (int i = 0; i < 3; ++i) {
 468                 for (int j = 0; j < 3; ++j) {
 469                         double sum = 0.0;
 470                         for (int k = 0; k < 3; ++k) {
 471                                 sum += a[i * 3 + k] * b[k * 3 + j];
 472                         }
 473                         res[i * 3 + j] = sum;
 474                 }
 475         }
 476 }
 477
 478 void VideoWidget::wheelEvent(QWheelEvent *event)
 479 {
 480         int delta = event->angleDelta().y();
 481         if (delta == 0) {
 482                 return;
 483         }
 484         double x = event->position().x() / width();
 485         double y = 1.0 - event->position().y() / height();
 486         double zoom = delta > 0 ? pow(1.005, delta) : pow(1/1.005, -delta);
 487
 488         const double inv_translation_matrix[9] = {
 489                 1.0, 0.0, 0.0,
 490                 0.0, 1.0, 0.0,
 491                 -x, -y, 1.0
 492         };
 493         const double scale_matrix[9] = {
 494                 zoom, 0.0, 0.0,
 495                 0.0, zoom, 0.0,
 496                 0.0, 0.0, 1.0
 497         };
 498         const double translation_matrix[9] = {
 499                 1.0, 0.0, 0.0,
 500                 0.0, 1.0, 0.0,
 501                 x, y, 1.0
 502         };
 503         double tmp1[9], tmp2[9];
 504         matmul3x3(zoom_matrix, inv_translation_matrix, tmp1);
 505         matmul3x3(tmp1, scale_matrix, tmp2);
 506         matmul3x3(tmp2, translation_matrix, zoom_matrix);
 507
 508         fixup_zoom_matrix();
 509         update();
 510 }
 511
 512 void VideoWidget::mousePressEvent(QMouseEvent *e)
 513 {
 514         if (e->button() == Qt::BackButton) {
 515                 emit mouse_back_clicked();
 516         } else if (e->button() == Qt::ForwardButton) {
 517                 emit mouse_forward_clicked();
 518         } else if (e->button() == Qt::LeftButton) {
 519                 dragging = true;
 520                 last_drag_x = e->position().x();
 521                 last_drag_y = e->position().y();
 522         }
 523 }
 524
 525 void VideoWidget::mouseReleaseEvent(QMouseEvent *e)
 526 {
 527         if (e->button() == Qt::LeftButton) {
 528                 dragging = false;
 529         }
 530 }
 531
 532 void VideoWidget::mouseMoveEvent(QMouseEvent *e)
 533 {
 534         if (!dragging) {
 535                 return;
 536         }
 537         float dx = (e->position().x() - last_drag_x) / width();
 538         float dy = (e->position().y() - last_drag_y) / height();
 539
 540         //zoom_matrix[6] += dx * zoom_matrix[0];
 541         //zoom_matrix[7] += dy * zoom_matrix[4];
 542         zoom_matrix[6] += dx;
 543         zoom_matrix[7] -= dy;
 544         fixup_zoom_matrix();
 545
 546         last_drag_x = e->position().x();
 547         last_drag_y = e->position().y();
 548
 549         update();
 550 }
 551
 552 // Normalize the matrix so that we never get skew or similar,
 553 // and also never can zoom or pan too far out.
 554 void VideoWidget::fixup_zoom_matrix()
 555 {
 556         // Correct for any numerical errors (we know the matrix must be orthogonal
 557         // and have zero rotation).
 558         zoom_matrix[4] = zoom_matrix[0];
 559         zoom_matrix[1] = zoom_matrix[2] = zoom_matrix[3] = zoom_matrix[5] = 0.0;
 560         zoom_matrix[8] = 1.0;
 561
 562         // We can't zoom further out than 1:1. (Perhaps it would be nice to
 563         // reuse the last zoom-in point to do this, but the center will have to do
 564         // for now.)
 565         if (zoom_matrix[0] < 1.0) {
 566                 const double zoom = 1.0 / zoom_matrix[0];
 567                 const double inv_translation_matrix[9] = {
 568                         1.0, 0.0, 0.0,
 569                         0.0, 1.0, 0.0,
 570                         -0.5, -0.5, 1.0
 571                 };
 572                 const double scale_matrix[9] = {
 573                         zoom, 0.0, 0.0,
 574                         0.0, zoom, 0.0,
 575                         0.0, 0.0, 1.0
 576                 };
 577                 const double translation_matrix[9] = {
 578                         1.0, 0.0, 0.0,
 579                         0.0, 1.0, 0.0,
 580                         0.5, 0.5, 1.0
 581                 };
 582                 double tmp1[9], tmp2[9];
 583                 matmul3x3(zoom_matrix, inv_translation_matrix, tmp1);
 584                 matmul3x3(tmp1, scale_matrix, tmp2);
 585                 matmul3x3(tmp2, translation_matrix, zoom_matrix);
 586         }
 587
 588         // Looking at the points we'll draw with glVertex2f(), make sure none of them are
 589         // inside the square (which would generally mean we've panned ourselves out-of-bounds).
 590         // We simply adjust the translation, which is possible because we fixed scaling above.
 591         zoom_matrix[6] = min(zoom_matrix[6], 0.0);  // Left side (x=0).
 592         zoom_matrix[7] = min(zoom_matrix[7], 0.0);  // Bottom side (y=0).
 593         zoom_matrix[6] = std::max(zoom_matrix[6], 1.0 - zoom_matrix[0]);  // Right side (x=1).
 594         zoom_matrix[7] = std::max(zoom_matrix[7], 1.0 - zoom_matrix[4]);  // Top side (y=1).
 595 }
 596
 597 bool VideoWidget::open(const string &filename)
 598 {
 599         stop();
 600         internal_rewind();
 601         pathname = filename;
 602         play();
 603
 604         while (running == STARTING) {
 605                 // Poor man's condition variable...
 606                 usleep(10000);
 607                 sched_yield();
 608         }
 609         return (running != VIDEO_FILE_ERROR);
 610 }
 611
 612 void VideoWidget::play()
 613 {
 614         if (running != NOT_RUNNING && running != VIDEO_FILE_ERROR) {
 615                 std::lock_guard<std::mutex> lock(queue_mu);
 616                 command_queue.push_back(QueuedCommand { QueuedCommand::RESUME });
 617                 producer_thread_should_quit.wakeup();
 618                 return;
 619         }
 620         running = STARTING;
 621         producer_thread_should_quit.unquit();
 622         if (producer_thread.joinable()) {
 623                 producer_thread.join();
 624         }
 625         producer_thread = std::thread(&VideoWidget::producer_thread_func, this);
 626 }
 627
 628 void VideoWidget::pause()
 629 {
 630         if (running == NOT_RUNNING || running == VIDEO_FILE_ERROR) {
 631                 return;
 632         }
 633         std::lock_guard<std::mutex> lock(queue_mu);
 634         command_queue.push_back(QueuedCommand { QueuedCommand::PAUSE });
 635         producer_thread_should_quit.wakeup();
 636 }
 637
 638 void VideoWidget::seek(int64_t relative_seek_ms)
 639 {
 640         if (running == NOT_RUNNING || running == VIDEO_FILE_ERROR) {
 641                 return;
 642         }
 643         std::lock_guard<std::mutex> lock(queue_mu);
 644         command_queue.push_back(QueuedCommand { QueuedCommand::SEEK, relative_seek_ms, 0, 0 });
 645         producer_thread_should_quit.wakeup();
 646 }
 647
 648 void VideoWidget::seek_frames(int64_t relative_seek_frames)
 649 {
 650         if (running == NOT_RUNNING || running == VIDEO_FILE_ERROR) {
 651                 return;
 652         }
 653         std::lock_guard<std::mutex> lock(queue_mu);
 654         command_queue.push_back(QueuedCommand { QueuedCommand::SEEK, 0, relative_seek_frames, 0 });
 655         producer_thread_should_quit.wakeup();
 656 }
 657
 658 void VideoWidget::seek_absolute(int64_t position_ms)
 659 {
 660         if (running == NOT_RUNNING || running == VIDEO_FILE_ERROR) {
 661                 return;
 662         }
 663         std::lock_guard<std::mutex> lock(queue_mu);
 664         command_queue.push_back(QueuedCommand { QueuedCommand::SEEK_ABSOLUTE, 0, 0, position_ms });
 665         producer_thread_should_quit.wakeup();
 666 }
 667
 668 void VideoWidget::stop()
 669 {
 670         if (running == NOT_RUNNING || running == VIDEO_FILE_ERROR) {
 671                 return;
 672         }
 673         producer_thread_should_quit.quit();
 674         producer_thread.join();
 675 }
 676
 677 void VideoWidget::producer_thread_func()
 678 {
 679         if (!producer_thread_should_quit.should_quit()) {
 680                 if (!play_video(pathname)) {
 681                         running = VIDEO_FILE_ERROR;
 682                 } else {
 683                         running = NOT_RUNNING;
 684                 }
 685         }
 686 }
 687
 688 void VideoWidget::internal_rewind()
 689 {
 690         pts_origin = last_pts = 0;
 691         last_position = 0;
 692         start = next_frame_start = steady_clock::now();
 693 }
 694
 695 template<AVHWDeviceType type>
 696 AVPixelFormat get_hw_format(AVCodecContext *ctx, const AVPixelFormat *fmt)
 697 {
 698         bool found_config_of_right_type = false;
 699         for (int i = 0;; ++i) {  // Termination condition inside loop.
 700                 const AVCodecHWConfig *config = avcodec_get_hw_config(ctx->codec, i);
 701                 if (config == nullptr) {  // End of list.
 702                         break;
 703                 }
 704                 if (!(config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX) ||
 705                     config->device_type != type) {
 706                         // Not interesting for us.
 707                         continue;
 708                 }
 709
 710                 // We have a config of the right type, but does it actually support
 711                 // the pixel format we want? (Seemingly, FFmpeg's way of signaling errors
 712                 // is to just replace the pixel format with a software-decoded one,
 713                 // such as yuv420p.)
 714                 found_config_of_right_type = true;
 715                 for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 716                         if (config->pix_fmt == *fmt_ptr) {
 717                                 fprintf(stderr, "Initialized '%s' hardware decoding for codec '%s'.\n",
 718                                         av_hwdevice_get_type_name(type), ctx->codec->name);
 719                                 if (ctx->profile == FF_PROFILE_H264_BASELINE) {
 720                                         fprintf(stderr, "WARNING: Stream claims to be H.264 Baseline, which is generally poorly supported in hardware decoders.\n");
 721                                         fprintf(stderr, "         Consider encoding it as Constrained Baseline, Main or High instead.\n");
 722                                         fprintf(stderr, "         Decoding might fail and fall back to software.\n");
 723                                 }
 724                                 return config->pix_fmt;
 725                         }
 726                 }
 727                 fprintf(stderr, "Decoder '%s' supports only these pixel formats:", ctx->codec->name);
 728                 unordered_set<AVPixelFormat> seen;
 729                 for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 730                         if (!seen.count(*fmt_ptr)) {
 731                                 fprintf(stderr, " %s", av_get_pix_fmt_name(*fmt_ptr));
 732                                 seen.insert(*fmt_ptr);
 733                         }
 734                 }
 735                 fprintf(stderr, " (wanted %s for hardware acceleration)\n", av_get_pix_fmt_name(config->pix_fmt));
 736
 737         }
 738
 739         if (!found_config_of_right_type) {
 740                 fprintf(stderr, "Decoder '%s' does not support device type '%s'.\n", ctx->codec->name, av_hwdevice_get_type_name(type));
 741         }
 742
 743         // We found no VA-API formats, so take the first software format.
 744         for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 745                 if ((av_pix_fmt_desc_get(*fmt_ptr)->flags & AV_PIX_FMT_FLAG_HWACCEL) == 0) {
 746                         fprintf(stderr, "Falling back to software format %s.\n", av_get_pix_fmt_name(*fmt_ptr));
 747                         return *fmt_ptr;
 748                 }
 749         }
 750
 751         // Fallback: Just return anything. (Should never really happen.)
 752         return fmt[0];
 753 }
 754
 755 AVFrameWithDeleter VideoWidget::decode_frame(AVFormatContext *format_ctx, AVCodecContext *video_codec_ctx,
 756         const std::string &pathname, int video_stream_index,
 757         bool *error)
 758 {
 759         *error = false;
 760
 761         if (!queued_frames.empty()) {
 762                 AVFrameWithDeleter frame = std::move(queued_frames.front());
 763                 queued_frames.pop_front();
 764                 return frame;
 765         }
 766
 767         // Read packets until we have a frame or there are none left.
 768         bool frame_finished = false;
 769         AVFrameWithDeleter video_avframe = av_frame_alloc_unique();
 770         bool eof = false;
 771         do {
 772                 AVPacket *pkt = av_packet_alloc();
 773                 unique_ptr<AVPacket, decltype(av_packet_unref)*> pkt_cleanup(
 774                         pkt, av_packet_unref);
 775                 pkt->data = nullptr;
 776                 pkt->size = 0;
 777                 if (av_read_frame(format_ctx, pkt) == 0) {
 778                         if (pkt->stream_index == video_stream_index) {
 779                                 if (avcodec_send_packet(video_codec_ctx, pkt) < 0) {
 780                                         fprintf(stderr, "%s: Cannot send packet to video codec.\n", pathname.c_str());
 781                                         *error = true;
 782                                         return AVFrameWithDeleter(nullptr);
 783                                 }
 784                         }
 785                 } else {
 786                         eof = true;  // Or error, but ignore that for the time being.
 787                 }
 788
 789                 // Decode video, if we have a frame.
 790                 int err = avcodec_receive_frame(video_codec_ctx, video_avframe.get());
 791                 if (err == 0) {
 792                         frame_finished = true;
 793                         break;
 794                 } else if (err != AVERROR(EAGAIN)) {
 795                         fprintf(stderr, "%s: Cannot receive frame from video codec.\n", pathname.c_str());
 796                         *error = true;
 797                         return AVFrameWithDeleter(nullptr);
 798                 }
 799         } while (!eof);
 800
 801         if (frame_finished)
 802                 return video_avframe;
 803         else
 804                 return AVFrameWithDeleter(nullptr);
 805 }
 806
 807 int find_stream_index(AVFormatContext *ctx, AVMediaType media_type)
 808 {
 809         for (unsigned i = 0; i < ctx->nb_streams; ++i) {
 810                 if (ctx->streams[i]->codecpar->codec_type == media_type) {
 811                         return i;
 812                 }
 813         }
 814         return -1;
 815 }
 816
 817 steady_clock::time_point compute_frame_start(int64_t frame_pts, int64_t pts_origin, const AVRational &video_timebase, const steady_clock::time_point &origin, double rate)
 818 {
 819         const duration<double> pts((frame_pts - pts_origin) * double(video_timebase.num) / double(video_timebase.den));
 820         return origin + duration_cast<steady_clock::duration>(pts / rate);
 821 }
 822
 823 bool VideoWidget::play_video(const string &pathname)
 824 {
 825         queued_frames.clear();
 826         AVFormatContextWithCloser format_ctx = avformat_open_input_unique(pathname.c_str(), /*fmt=*/nullptr,
 827                 /*options=*/nullptr);
 828         if (format_ctx == nullptr) {
 829                 fprintf(stderr, "%s: Error opening file\n", pathname.c_str());
 830                 return false;
 831         }
 832
 833         if (avformat_find_stream_info(format_ctx.get(), nullptr) < 0) {
 834                 fprintf(stderr, "%s: Error finding stream info\n", pathname.c_str());
 835                 return false;
 836         }
 837
 838         int video_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_VIDEO);
 839         if (video_stream_index == -1) {
 840                 fprintf(stderr, "%s: No video stream found\n", pathname.c_str());
 841                 return false;
 842         }
 843
 844         // Open video decoder.
 845         const AVCodecParameters *video_codecpar = format_ctx->streams[video_stream_index]->codecpar;
 846         const AVCodec *video_codec = avcodec_find_decoder(video_codecpar->codec_id);
 847
 848         video_timebase = format_ctx->streams[video_stream_index]->time_base;
 849         AVCodecContextWithDeleter video_codec_ctx = avcodec_alloc_context3_unique(nullptr);
 850         if (avcodec_parameters_to_context(video_codec_ctx.get(), video_codecpar) < 0) {
 851                 fprintf(stderr, "%s: Cannot fill video codec parameters\n", pathname.c_str());
 852                 return false;
 853         }
 854         if (video_codec == nullptr) {
 855                 fprintf(stderr, "%s: Cannot find video decoder\n", pathname.c_str());
 856                 return false;
 857         }
 858
 859         // Seemingly, it's not too easy to make something that just initializes
 860         // “whatever goes”, so we don't get CUDA or VULKAN or whatever here
 861         // without enumerating through several different types.
 862         // VA-API and VDPAU will do for now. We prioritize VDPAU for the
 863         // simple reason that there's a VA-API-via-VDPAU emulation for NVidia
 864         // cards that seems to work, but just hangs when trying to transfer the frame.
 865         //
 866         // Note that we don't actually check codec support beforehand,
 867         // so if you have a low-end VDPAU device but a high-end VA-API device,
 868         // you lose out on the extra codec support from the latter.
 869         AVBufferRef *hw_device_ctx = nullptr;
 870         if (av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VDPAU, nullptr, nullptr, 0) >= 0) {
 871                 video_codec_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 872                 video_codec_ctx->get_format = get_hw_format<AV_HWDEVICE_TYPE_VDPAU>;
 873         } else if (av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VAAPI, nullptr, nullptr, 0) >= 0) {
 874                 video_codec_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 875                 video_codec_ctx->get_format = get_hw_format<AV_HWDEVICE_TYPE_VAAPI>;
 876         } else {
 877                 fprintf(stderr, "Failed to initialize VA-API or VDPAU for FFmpeg acceleration. Decoding video in software.\n");
 878         }
 879
 880         if (avcodec_open2(video_codec_ctx.get(), video_codec, nullptr) < 0) {
 881                 fprintf(stderr, "%s: Cannot open video decoder\n", pathname.c_str());
 882                 return false;
 883         }
 884         unique_ptr<AVCodecContext, decltype(avcodec_close)*> video_codec_ctx_cleanup(
 885                 video_codec_ctx.get(), avcodec_close);
 886
 887         internal_rewind();
 888
 889         running = RUNNING;
 890
 891         // Main loop.
 892         int consecutive_errors = 0;
 893         double rate = 1.0;
 894         while (!producer_thread_should_quit.should_quit()) {
 895                 if (process_queued_commands(format_ctx.get(), video_codec_ctx.get(), video_stream_index, /*seeked=*/nullptr)) {
 896                         return true;
 897                 }
 898                 if (paused) {
 899                         producer_thread_should_quit.sleep_for(hours(1));
 900                         continue;
 901                 }
 902
 903                 bool error;
 904                 AVFrameWithDeleter frame = decode_frame(format_ctx.get(), video_codec_ctx.get(),
 905                         pathname, video_stream_index, &error);
 906                 if (error) {
 907                         if (++consecutive_errors >= 100) {
 908                                 fprintf(stderr, "More than 100 consecutive video frames, aborting playback.\n");
 909                                 return false;
 910                         } else {
 911                                 continue;
 912                         }
 913                 } else {
 914                         consecutive_errors = 0;
 915                 }
 916                 if (frame == nullptr) {
 917                         // EOF.
 918                         return false;
 919                 }
 920
 921                 // Sleep until it's time to present this frame.
 922                 for ( ;; ) {
 923                         if (last_pts == 0 && pts_origin == 0) {
 924                                 pts_origin = frame->pts;
 925                         }
 926                         steady_clock::time_point now = steady_clock::now();
 927                         next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
 928
 929                         if (duration<double>(now - next_frame_start).count() >= 0.1) {
 930                                 // If we don't have enough CPU to keep up, or if we have a live stream
 931                                 // where the initial origin was somehow wrong, we could be behind indefinitely.
 932                                 fprintf(stderr, "%s: Playback %.0f ms behind, resetting time scale\n",
 933                                         pathname.c_str(),
 934                                         1e3 * duration<double>(now - next_frame_start).count());
 935                                 pts_origin = frame->pts;
 936                                 start = next_frame_start = now;
 937                         }
 938                         bool finished_wakeup;
 939                         finished_wakeup = producer_thread_should_quit.sleep_until(next_frame_start);
 940                         if (finished_wakeup) {
 941                                 Frame *new_frame = new Frame(make_video_frame(frame.get()));
 942                                 {
 943                                         lock_guard lock(current_frame_mu);
 944                                         current_frame.reset(new_frame);
 945                                 }
 946                                 last_frame = steady_clock::now();
 947                                 update();
 948                                 break;
 949                         } else {
 950                                 if (producer_thread_should_quit.should_quit()) break;
 951
 952                                 bool seeked = false;
 953                                 if (process_queued_commands(format_ctx.get(), video_codec_ctx.get(), video_stream_index, &seeked)) {
 954                                         return true;
 955                                 }
 956
 957                                 if (paused) {
 958                                         // Just paused, so present the frame immediately and then go into deep sleep.
 959                                         Frame *new_frame = new Frame(make_video_frame(frame.get()));
 960                                         {
 961                                                 lock_guard lock(current_frame_mu);
 962                                                 current_frame.reset(new_frame);
 963                                         }
 964                                         last_frame = steady_clock::now();
 965                                         update();
 966                                         break;
 967                                 }
 968
 969                                 // If we just seeked, drop this frame on the floor and be done.
 970                                 if (seeked) {
 971                                         break;
 972                                 }
 973                         }
 974                 }
 975                 store_pts(frame->pts);
 976         }
 977         return true;
 978 }
 979
 980 void VideoWidget::store_pts(int64_t pts)
 981 {
 982         last_pts = pts;
 983         last_position = lrint(pts * double(video_timebase.num) / double(video_timebase.den) * 1000);
 984         post_to_main_thread([this, last_position{last_position.load()}] {
 985                 emit position_changed(last_position);
 986         });
 987 }
 988
 989 // Taken from Movit (see the comment there for explanation)
 990 float compute_chroma_offset(float pos, unsigned subsampling_factor, unsigned resolution)
 991 {
 992         float local_chroma_pos = (0.5 + pos * (subsampling_factor - 1)) / subsampling_factor;
 993         if (fabs(local_chroma_pos - 0.5) < 1e-10) {
 994                 // x + (-0) can be optimized away freely, as opposed to x + 0.
 995                 return -0.0;
 996         } else {
 997                 return (0.5 - local_chroma_pos) / resolution;
 998         }
 999 }
1000
1001 VideoWidget::Frame VideoWidget::make_video_frame(const AVFrame *frame)
1002 {
1003         Frame video_frame;
1004         AVFrameWithDeleter sw_frame;
1005
1006         if (frame->format == AV_PIX_FMT_VAAPI ||
1007             frame->format == AV_PIX_FMT_VDPAU) {
1008                 // Get the frame down to the CPU. (TODO: See if we can keep it
1009                 // on the GPU all the way, since it will be going up again later.
1010                 // However, this only works if the OpenGL GPU is the same one.)
1011                 sw_frame = av_frame_alloc_unique();
1012                 int err = av_hwframe_transfer_data(sw_frame.get(), frame, 0);
1013                 if (err != 0) {
1014                         fprintf(stderr, "%s: Cannot transfer hardware video frame to software.\n", pathname.c_str());
1015                 } else {
1016                         sw_frame->pts = frame->pts;
1017                         sw_frame->pkt_duration = frame->pkt_duration;
1018                         frame = sw_frame.get();
1019                 }
1020         }
1021
1022         if (sws_ctx == nullptr ||
1023             sws_last_width != frame->width ||
1024             sws_last_height != frame->height ||
1025             sws_last_src_format != frame->format) {
1026                 sws_dst_format = decide_dst_format(AVPixelFormat(frame->format));
1027                 sws_ctx.reset(
1028                         sws_getContext(frame->width, frame->height, AVPixelFormat(frame->format),
1029                                 frame->width, frame->height, sws_dst_format,
1030                                 SWS_BICUBIC, nullptr, nullptr, nullptr));
1031                 sws_last_width = frame->width;
1032                 sws_last_height = frame->height;
1033                 sws_last_src_format = frame->format;
1034         }
1035         if (sws_ctx == nullptr) {
1036                 fprintf(stderr, "Could not create scaler context\n");
1037                 abort();
1038         }
1039
1040         uint8_t *pic_data[4] = { nullptr, nullptr, nullptr, nullptr };
1041         int linesizes[4] = { 0, 0, 0, 0 };
1042         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(sws_dst_format);
1043
1044         video_frame.width = frame->width;
1045         video_frame.height = frame->height;
1046         video_frame.chroma_width = AV_CEIL_RSHIFT(int(frame->width), desc->log2_chroma_w);
1047         video_frame.chroma_height = AV_CEIL_RSHIFT(int(frame->height), desc->log2_chroma_h);
1048
1049         // We always assume left chroma placement for now.
1050         cbcr_offset[0] = compute_chroma_offset(0.0f, 1 << desc->log2_chroma_w, video_frame.chroma_width);
1051         cbcr_offset[1] = compute_chroma_offset(0.5f, 1 << desc->log2_chroma_h, video_frame.chroma_height);
1052
1053         size_t len = frame->width * frame->height + 2 * video_frame.chroma_width * video_frame.chroma_height;
1054         video_frame.data.reset(new uint8_t[len]);
1055
1056         pic_data[0] = video_frame.data.get();
1057         linesizes[0] = frame->width;
1058
1059         pic_data[1] = pic_data[0] + frame->width * frame->height;
1060         linesizes[1] = video_frame.chroma_width;
1061
1062         pic_data[2] = pic_data[1] + video_frame.chroma_width * video_frame.chroma_height;
1063         linesizes[2] = video_frame.chroma_width;
1064
1065         sws_scale(sws_ctx.get(), frame->data, frame->linesize, 0, frame->height, pic_data, linesizes);
1066
1067         return video_frame;
1068 }
1069