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

   1 #include "ffmpeg_capture.h"
   2 #include "defs.h"
   3 #include "shared/shared_defs.h"
   4
   5 #include <assert.h>
   6 #include <cerrno>
   7 #include <ctime>
   8 #include <limits>
   9 #include <map>
  10 #include <memory>
  11 #include <movit/effect.h>
  12 #include <movit/image_format.h>
  13 #include <movit/ycbcr.h>
  14 #include <mutex>
  15 #include <pthread.h>
  16 #include <stdint.h>
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <string>
  21 #include <sys/stat.h>
  22 #include <thread>
  23
  24 extern "C" {
  25 #include <libavcodec/avcodec.h>
  26 #include <libavcodec/codec.h>
  27 #include <libavcodec/codec_id.h>
  28 #include <libavcodec/codec_par.h>
  29 #include <libavformat/avformat.h>
  30 #include <libavutil/avutil.h>
  31 #include <libavutil/buffer.h>
  32 #include <libavutil/channel_layout.h>
  33 #include <libavutil/common.h>
  34 #include <libavutil/dict.h>
  35 #include <libavutil/error.h>
  36 #include <libavutil/frame.h>
  37 #include <libavutil/hwcontext.h>
  38 #include <libavutil/mathematics.h>
  39 #include <libavutil/pixdesc.h>
  40 #include <libavutil/pixfmt.h>
  41 #include <libavutil/rational.h>
  42 #include <libavutil/samplefmt.h>
  43 #include <libavutil/version.h>
  44 #include <libswresample/swresample.h>
  45 #include <libswscale/swscale.h>
  46 }
  47
  48 #include <chrono>
  49 #include <cstdint>
  50 #include <utility>
  51 #include <vector>
  52 #include <unordered_set>
  53
  54 #include <Eigen/Core>
  55 #include <Eigen/LU>
  56 #include <movit/colorspace_conversion_effect.h>
  57
  58 #include "bmusb/bmusb.h"
  59 #include "shared/ffmpeg_raii.h"
  60 #include "ffmpeg_util.h"
  61 #include "flags.h"
  62 #include "ref_counted_frame.h"
  63 #include "shared/timebase.h"
  64
  65 #ifdef HAVE_SRT
  66 #include <srt/srt.h>
  67 #endif
  68
  69 using namespace std;
  70 using namespace std::chrono;
  71 using namespace bmusb;
  72 using namespace movit;
  73 using namespace Eigen;
  74
  75 // Avoid deprecation warnings, but we don't want to drop FFmpeg 5.1 support just yet.
  76 #if LIBAVUTIL_VERSION_INT >= AV_VERSION_INT(57, 30, 100)
  77 #define pkt_duration duration
  78 #endif
  79
  80 namespace {
  81
  82 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)
  83 {
  84         const duration<double> pts((frame_pts - pts_origin) * double(video_timebase.num) / double(video_timebase.den));
  85         return origin + duration_cast<steady_clock::duration>(pts / rate);
  86 }
  87
  88 bool changed_since(const std::string &pathname, const timespec &ts)
  89 {
  90         if (ts.tv_sec < 0) {
  91                 return false;
  92         }
  93         struct stat buf;
  94         if (stat(pathname.c_str(), &buf) != 0) {
  95                 fprintf(stderr, "%s: Couldn't check for new version, leaving the old in place.\n", pathname.c_str());
  96                 return false;
  97         }
  98         return (buf.st_mtim.tv_sec != ts.tv_sec || buf.st_mtim.tv_nsec != ts.tv_nsec);
  99 }
 100
 101 bool is_full_range(const AVPixFmtDescriptor *desc)
 102 {
 103         // This is horrible, but there's no better way that I know of.
 104         return (strchr(desc->name, 'j') != nullptr);
 105 }
 106
 107 AVPixelFormat decide_dst_format(AVPixelFormat src_format, bmusb::PixelFormat dst_format_type)
 108 {
 109         if (dst_format_type == bmusb::PixelFormat_8BitBGRA) {
 110                 return AV_PIX_FMT_BGRA;
 111         }
 112         if (dst_format_type == FFmpegCapture::PixelFormat_NV12) {
 113                 return AV_PIX_FMT_NV12;
 114         }
 115
 116         assert(dst_format_type == bmusb::PixelFormat_8BitYCbCrPlanar);
 117
 118         // If this is a non-Y'CbCr format, just convert to 4:4:4 Y'CbCr
 119         // and be done with it. It's too strange to spend a lot of time on.
 120         // (Let's hope there's no alpha.)
 121         const AVPixFmtDescriptor *src_desc = av_pix_fmt_desc_get(src_format);
 122         if (src_desc == nullptr ||
 123             src_desc->nb_components != 3 ||
 124             (src_desc->flags & AV_PIX_FMT_FLAG_RGB)) {
 125                 return AV_PIX_FMT_YUV444P;
 126         }
 127
 128         // The best for us would be Cb and Cr together if possible,
 129         // but FFmpeg doesn't support that except in the special case of
 130         // NV12, so we need to go to planar even for the case of NV12.
 131         // Thus, look for the closest (but no worse) 8-bit planar Y'CbCr format
 132         // that matches in color range. (This will also include the case of
 133         // the source format already being acceptable.)
 134         bool src_full_range = is_full_range(src_desc);
 135         const char *best_format = "yuv444p";
 136         unsigned best_score = numeric_limits<unsigned>::max();
 137         for (const AVPixFmtDescriptor *desc = av_pix_fmt_desc_next(nullptr);
 138              desc;
 139              desc = av_pix_fmt_desc_next(desc)) {
 140                 // Find planar Y'CbCr formats only.
 141                 if (desc->nb_components != 3) continue;
 142                 if (desc->flags & AV_PIX_FMT_FLAG_RGB) continue;
 143                 if (!(desc->flags & AV_PIX_FMT_FLAG_PLANAR)) continue;
 144                 if (desc->comp[0].plane != 0 ||
 145                     desc->comp[1].plane != 1 ||
 146                     desc->comp[2].plane != 2) continue;
 147
 148                 // 8-bit formats only.
 149                 if (desc->flags & AV_PIX_FMT_FLAG_BE) continue;
 150                 if (desc->comp[0].depth != 8) continue;
 151
 152                 // Same or better chroma resolution only.
 153                 int chroma_w_diff = src_desc->log2_chroma_w - desc->log2_chroma_w;
 154                 int chroma_h_diff = src_desc->log2_chroma_h - desc->log2_chroma_h;
 155                 if (chroma_w_diff < 0 || chroma_h_diff < 0)
 156                         continue;
 157
 158                 // Matching full/limited range only.
 159                 if (is_full_range(desc) != src_full_range)
 160                         continue;
 161
 162                 // Pick something with as little excess chroma resolution as possible.
 163                 unsigned score = (1 << (chroma_w_diff)) << chroma_h_diff;
 164                 if (score < best_score) {
 165                         best_score = score;
 166                         best_format = desc->name;
 167                 }
 168         }
 169         return av_get_pix_fmt(best_format);
 170 }
 171
 172 YCbCrFormat decode_ycbcr_format(const AVPixFmtDescriptor *desc, const AVFrame *frame, bool is_mjpeg, AVColorSpace *last_colorspace, AVChromaLocation *last_chroma_location)
 173 {
 174         YCbCrFormat format;
 175         AVColorSpace colorspace = frame->colorspace;
 176         switch (colorspace) {
 177         case AVCOL_SPC_BT709:
 178                 format.luma_coefficients = YCBCR_REC_709;
 179                 break;
 180         case AVCOL_SPC_BT470BG:
 181         case AVCOL_SPC_SMPTE170M:
 182         case AVCOL_SPC_SMPTE240M:
 183                 format.luma_coefficients = YCBCR_REC_601;
 184                 break;
 185         case AVCOL_SPC_BT2020_NCL:
 186                 format.luma_coefficients = YCBCR_REC_2020;
 187                 break;
 188         case AVCOL_SPC_UNSPECIFIED:
 189                 format.luma_coefficients = (frame->height >= 720 ? YCBCR_REC_709 : YCBCR_REC_601);
 190                 break;
 191         default:
 192                 if (colorspace != *last_colorspace) {
 193                         fprintf(stderr, "Unknown Y'CbCr coefficient enum %d from FFmpeg; choosing Rec. 709.\n",
 194                                 colorspace);
 195                 }
 196                 format.luma_coefficients = YCBCR_REC_709;
 197                 break;
 198         }
 199         *last_colorspace = colorspace;
 200
 201         format.full_range = is_full_range(desc);
 202         format.num_levels = 1 << desc->comp[0].depth;
 203         format.chroma_subsampling_x = 1 << desc->log2_chroma_w;
 204         format.chroma_subsampling_y = 1 << desc->log2_chroma_h;
 205
 206         switch (frame->chroma_location) {
 207         case AVCHROMA_LOC_LEFT:
 208                 format.cb_x_position = 0.0;
 209                 format.cb_y_position = 0.5;
 210                 break;
 211         case AVCHROMA_LOC_CENTER:
 212                 format.cb_x_position = 0.5;
 213                 format.cb_y_position = 0.5;
 214                 break;
 215         case AVCHROMA_LOC_TOPLEFT:
 216                 format.cb_x_position = 0.0;
 217                 format.cb_y_position = 0.0;
 218                 break;
 219         case AVCHROMA_LOC_TOP:
 220                 format.cb_x_position = 0.5;
 221                 format.cb_y_position = 0.0;
 222                 break;
 223         case AVCHROMA_LOC_BOTTOMLEFT:
 224                 format.cb_x_position = 0.0;
 225                 format.cb_y_position = 1.0;
 226                 break;
 227         case AVCHROMA_LOC_BOTTOM:
 228                 format.cb_x_position = 0.5;
 229                 format.cb_y_position = 1.0;
 230                 break;
 231         default:
 232                 if (frame->chroma_location != *last_chroma_location) {
 233                         fprintf(stderr, "Unknown chroma location coefficient enum %d from FFmpeg; choosing center.\n",
 234                                 frame->chroma_location);
 235                 }
 236                 format.cb_x_position = 0.5;
 237                 format.cb_y_position = 0.5;
 238                 break;
 239         }
 240         *last_chroma_location = frame->chroma_location;
 241
 242         if (is_mjpeg && !format.full_range) {
 243                 // Limited-range MJPEG is only detected by FFmpeg whenever a special
 244                 // JPEG comment is set, which means that in practice, the stream is
 245                 // almost certainly generated by Futatabi. Override FFmpeg's forced
 246                 // MJPEG defaults (it disregards the values set in the mux) with what
 247                 // Futatabi sets.
 248                 format.luma_coefficients = YCBCR_REC_709;
 249                 format.cb_x_position = 0.0;
 250                 format.cb_y_position = 0.5;
 251         }
 252
 253         format.cr_x_position = format.cb_x_position;
 254         format.cr_y_position = format.cb_y_position;
 255         return format;
 256 }
 257
 258 RGBTriplet get_neutral_color(AVDictionary *metadata)
 259 {
 260         if (metadata == nullptr) {
 261                 return RGBTriplet(1.0f, 1.0f, 1.0f);
 262         }
 263         AVDictionaryEntry *entry = av_dict_get(metadata, "WhitePoint", nullptr, 0);
 264         if (entry == nullptr) {
 265                 return RGBTriplet(1.0f, 1.0f, 1.0f);
 266         }
 267
 268         unsigned x_nom, x_den, y_nom, y_den;
 269         if (sscanf(entry->value, " %u:%u , %u:%u", &x_nom, &x_den, &y_nom, &y_den) != 4) {
 270                 fprintf(stderr, "WARNING: Unable to parse white point '%s', using default white point\n", entry->value);
 271                 return RGBTriplet(1.0f, 1.0f, 1.0f);
 272         }
 273
 274         double x = double(x_nom) / x_den;
 275         double y = double(y_nom) / y_den;
 276         double z = 1.0 - x - y;
 277
 278         Matrix3d rgb_to_xyz_matrix = movit::ColorspaceConversionEffect::get_xyz_matrix(COLORSPACE_sRGB);
 279         Vector3d rgb = rgb_to_xyz_matrix.inverse() * Vector3d(x, y, z);
 280
 281         return RGBTriplet(rgb[0], rgb[1], rgb[2]);
 282 }
 283
 284 }  // namespace
 285
 286 FFmpegCapture::FFmpegCapture(const string &filename, unsigned width, unsigned height)
 287         : filename(filename), width(width), height(height), video_timebase{1, 1}
 288 {
 289         description = "Video: " + filename;
 290
 291         last_frame = steady_clock::now();
 292
 293         avformat_network_init();  // In case someone wants this.
 294 }
 295
 296 #ifdef HAVE_SRT
 297 FFmpegCapture::FFmpegCapture(int srt_sock, const string &stream_id)
 298         : srt_sock(srt_sock),
 299           width(0),  // Don't resize; SRT streams typically have stable resolution, and should behave much like regular cards in general.
 300           height(0),
 301           pixel_format(bmusb::PixelFormat_8BitYCbCrPlanar),
 302           video_timebase{1, 1}
 303 {
 304         if (stream_id.empty()) {
 305                 description = "SRT stream";
 306         } else {
 307                 description = stream_id;
 308         }
 309         play_as_fast_as_possible = true;
 310         play_once = true;
 311         last_frame = steady_clock::now();
 312 }
 313 #endif
 314
 315 FFmpegCapture::~FFmpegCapture()
 316 {
 317         if (has_dequeue_callbacks) {
 318                 dequeue_cleanup_callback();
 319         }
 320         swr_free(&resampler);
 321 #ifdef HAVE_SRT
 322         if (srt_sock != -1) {
 323                 srt_close(srt_sock);
 324         }
 325 #endif
 326 }
 327
 328 void FFmpegCapture::configure_card()
 329 {
 330         if (video_frame_allocator == nullptr) {
 331                 owned_video_frame_allocator.reset(new MallocFrameAllocator(FRAME_SIZE, NUM_QUEUED_VIDEO_FRAMES));
 332                 set_video_frame_allocator(owned_video_frame_allocator.get());
 333         }
 334         if (audio_frame_allocator == nullptr) {
 335                 // Audio can come out in pretty large chunks, so increase from the default 1 MB.
 336                 owned_audio_frame_allocator.reset(new MallocFrameAllocator(1 << 20, NUM_QUEUED_AUDIO_FRAMES));
 337                 set_audio_frame_allocator(owned_audio_frame_allocator.get());
 338         }
 339 }
 340
 341 void FFmpegCapture::start_bm_capture()
 342 {
 343         if (running) {
 344                 return;
 345         }
 346         running = true;
 347         producer_thread_should_quit.unquit();
 348         producer_thread = thread(&FFmpegCapture::producer_thread_func, this);
 349 }
 350
 351 void FFmpegCapture::stop_dequeue_thread()
 352 {
 353         if (!running) {
 354                 return;
 355         }
 356         running = false;
 357         producer_thread_should_quit.quit();
 358         producer_thread.join();
 359 }
 360
 361 std::map<uint32_t, VideoMode> FFmpegCapture::get_available_video_modes() const
 362 {
 363         // Note: This will never really be shown in the UI.
 364         VideoMode mode;
 365
 366         char buf[256];
 367         snprintf(buf, sizeof(buf), "%ux%u", sws_last_width, sws_last_height);
 368         mode.name = buf;
 369
 370         mode.autodetect = false;
 371         mode.width = sws_last_width;
 372         mode.height = sws_last_height;
 373         mode.frame_rate_num = 60;
 374         mode.frame_rate_den = 1;
 375         mode.interlaced = false;
 376
 377         return {{ 0, mode }};
 378 }
 379
 380 void FFmpegCapture::producer_thread_func()
 381 {
 382         char thread_name[16];
 383         snprintf(thread_name, sizeof(thread_name), "FFmpeg_C_%d", card_index);
 384         pthread_setname_np(pthread_self(), thread_name);
 385
 386         while (!producer_thread_should_quit.should_quit()) {
 387                 string filename_copy;
 388                 {
 389                         lock_guard<mutex> lock(filename_mu);
 390                         filename_copy = filename;
 391                 }
 392
 393                 string pathname;
 394                 if (srt_sock == -1) {
 395                         pathname = search_for_file(filename_copy);
 396                 } else {
 397                         pathname = description;
 398                 }
 399                 if (pathname.empty()) {
 400                         send_disconnected_frame();
 401                         if (play_once) {
 402                                 break;
 403                         }
 404                         producer_thread_should_quit.sleep_for(seconds(1));
 405                         fprintf(stderr, "%s not found, sleeping one second and trying again...\n", filename_copy.c_str());
 406                         continue;
 407                 }
 408                 should_interrupt = false;
 409                 if (!play_video(pathname)) {
 410                         // Error.
 411                         send_disconnected_frame();
 412                         if (play_once) {
 413                                 break;
 414                         }
 415                         fprintf(stderr, "Error when playing %s, sleeping one second and trying again...\n", pathname.c_str());
 416                         producer_thread_should_quit.sleep_for(seconds(1));
 417                         continue;
 418                 }
 419
 420                 if (play_once) {
 421                         send_disconnected_frame();
 422                         break;
 423                 }
 424
 425                 // Probably just EOF, will exit the loop above on next test.
 426         }
 427
 428         if (has_dequeue_callbacks) {
 429                 dequeue_cleanup_callback();
 430                 has_dequeue_callbacks = false;
 431         }
 432 }
 433
 434 void FFmpegCapture::send_disconnected_frame()
 435 {
 436         // Send an empty frame to signal that we have no signal anymore.
 437         FrameAllocator::Frame video_frame = video_frame_allocator->alloc_frame();
 438         size_t frame_width = width == 0 ? global_flags.width : width;
 439         size_t frame_height = height == 0 ? global_flags.height : height;
 440         if (video_frame.data) {
 441                 VideoFormat video_format;
 442                 video_format.width = frame_width;
 443                 video_format.height = frame_height;
 444                 video_format.frame_rate_nom = 60;
 445                 video_format.frame_rate_den = 1;
 446                 video_format.is_connected = false;
 447                 if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
 448                         video_format.stride = frame_width * 4;
 449                         video_frame.len = frame_width * frame_height * 4;
 450                         memset(video_frame.data, 0, video_frame.len);
 451                 } else {
 452                         video_format.stride = frame_width;
 453                         current_frame_ycbcr_format.luma_coefficients = YCBCR_REC_709;
 454                         current_frame_ycbcr_format.full_range = true;
 455                         current_frame_ycbcr_format.num_levels = 256;
 456                         current_frame_ycbcr_format.chroma_subsampling_x = 2;
 457                         current_frame_ycbcr_format.chroma_subsampling_y = 2;
 458                         current_frame_ycbcr_format.cb_x_position = 0.0f;
 459                         current_frame_ycbcr_format.cb_y_position = 0.0f;
 460                         current_frame_ycbcr_format.cr_x_position = 0.0f;
 461                         current_frame_ycbcr_format.cr_y_position = 0.0f;
 462                         video_frame.len = frame_width * frame_height * 2;
 463                         memset(video_frame.data, 0, frame_width * frame_height);
 464                         memset(video_frame.data + frame_width * frame_height, 128, frame_width * frame_height);  // Valid for both NV12 and planar.
 465                 }
 466
 467                 if (frame_callback != nullptr) {
 468                         frame_callback(-1, AVRational{1, TIMEBASE}, -1, AVRational{1, TIMEBASE}, timecode++,
 469                                 video_frame, /*video_offset=*/0, video_format,
 470                                 FrameAllocator::Frame(), /*audio_offset=*/0, AudioFormat());
 471                 }
 472                 last_frame_was_connected = false;
 473         }
 474
 475         if (play_once) {
 476                 disconnected = true;
 477                 if (card_disconnected_callback != nullptr) {
 478                         card_disconnected_callback();
 479                 }
 480         }
 481 }
 482
 483 template<AVHWDeviceType type>
 484 AVPixelFormat get_hw_format(AVCodecContext *ctx, const AVPixelFormat *fmt)
 485 {
 486         bool found_config_of_right_type = false;
 487         for (int i = 0;; ++i) {  // Termination condition inside loop.
 488                 const AVCodecHWConfig *config = avcodec_get_hw_config(ctx->codec, i);
 489                 if (config == nullptr) {  // End of list.
 490                         break;
 491                 }
 492                 if (!(config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX) ||
 493                     config->device_type != type) {
 494                         // Not interesting for us.
 495                         continue;
 496                 }
 497
 498                 // We have a config of the right type, but does it actually support
 499                 // the pixel format we want? (Seemingly, FFmpeg's way of signaling errors
 500                 // is to just replace the pixel format with a software-decoded one,
 501                 // such as yuv420p.)
 502                 found_config_of_right_type = true;
 503                 for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 504                         if (config->pix_fmt == *fmt_ptr) {
 505                                 fprintf(stderr, "Initialized '%s' hardware decoding for codec '%s'.\n",
 506                                         av_hwdevice_get_type_name(type), ctx->codec->name);
 507                                 if (ctx->profile == FF_PROFILE_H264_BASELINE) {
 508                                         fprintf(stderr, "WARNING: Stream claims to be H.264 Baseline, which is generally poorly supported in hardware decoders.\n");
 509                                         fprintf(stderr, "         Consider encoding it as Constrained Baseline, Main or High instead.\n");
 510                                         fprintf(stderr, "         Decoding might fail and fall back to software.\n");
 511                                 }
 512                                 return config->pix_fmt;
 513                         }
 514                 }
 515                 fprintf(stderr, "Decoder '%s' supports only these pixel formats:", ctx->codec->name);
 516                 unordered_set<AVPixelFormat> seen;
 517                 for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 518                         if (!seen.count(*fmt_ptr)) {
 519                                 fprintf(stderr, " %s", av_get_pix_fmt_name(*fmt_ptr));
 520                                 seen.insert(*fmt_ptr);
 521                         }
 522                 }
 523                 fprintf(stderr, " (wanted %s for hardware acceleration)\n", av_get_pix_fmt_name(config->pix_fmt));
 524
 525         }
 526
 527         if (!found_config_of_right_type) {
 528                 fprintf(stderr, "Decoder '%s' does not support device type '%s'.\n", ctx->codec->name, av_hwdevice_get_type_name(type));
 529         }
 530
 531         // We found no VA-API formats, so take the first software format.
 532         for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 533                 if ((av_pix_fmt_desc_get(*fmt_ptr)->flags & AV_PIX_FMT_FLAG_HWACCEL) == 0) {
 534                         fprintf(stderr, "Falling back to software format %s.\n", av_get_pix_fmt_name(*fmt_ptr));
 535                         return *fmt_ptr;
 536                 }
 537         }
 538
 539         // Fallback: Just return anything. (Should never really happen.)
 540         return fmt[0];
 541 }
 542
 543 bool FFmpegCapture::play_video(const string &pathname)
 544 {
 545         // Note: Call before open, not after; otherwise, there's a race.
 546         // (There is now, too, but it tips the correct way. We could use fstat()
 547         // if we had the file descriptor.)
 548         timespec last_modified;
 549         struct stat buf;
 550         if (stat(pathname.c_str(), &buf) != 0) {
 551                 // Probably some sort of protocol, so can't stat.
 552                 last_modified.tv_sec = -1;
 553         } else {
 554                 last_modified = buf.st_mtim;
 555         }
 556         last_colorspace = static_cast<AVColorSpace>(-1);
 557         last_chroma_location = static_cast<AVChromaLocation>(-1);
 558
 559         AVFormatContextWithCloser format_ctx;
 560         if (srt_sock == -1) {
 561                 // Regular file (or stream).
 562                 frame_timeout_started = steady_clock::now();
 563                 frame_timeout_valid = true;
 564                 format_ctx = avformat_open_input_unique(pathname.c_str(), /*fmt=*/nullptr,
 565                         /*options=*/nullptr,
 566                         AVIOInterruptCB{ &FFmpegCapture::interrupt_cb_thunk, this });
 567                 frame_timeout_valid = false;
 568         } else {
 569 #ifdef HAVE_SRT
 570                 // SRT socket, already opened.
 571                 const AVInputFormat *mpegts_fmt = av_find_input_format("mpegts");
 572                 format_ctx = avformat_open_input_unique(&FFmpegCapture::read_srt_thunk, this,
 573                         mpegts_fmt, /*options=*/nullptr,
 574                         AVIOInterruptCB{ &FFmpegCapture::interrupt_cb_thunk, this });
 575 #else
 576                 assert(false);
 577 #endif
 578         }
 579         if (format_ctx == nullptr) {
 580                 fprintf(stderr, "%s: Error opening file\n", pathname.c_str());
 581                 return false;
 582         }
 583
 584         if (avformat_find_stream_info(format_ctx.get(), nullptr) < 0) {
 585                 fprintf(stderr, "%s: Error finding stream info\n", pathname.c_str());
 586                 return false;
 587         }
 588
 589         int video_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_VIDEO);
 590         if (video_stream_index == -1) {
 591                 fprintf(stderr, "%s: No video stream found\n", pathname.c_str());
 592                 return false;
 593         }
 594
 595         int audio_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_AUDIO);
 596         int subtitle_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_SUBTITLE);
 597         has_last_subtitle = false;
 598
 599         // Open video decoder.
 600         const AVCodecParameters *video_codecpar = format_ctx->streams[video_stream_index]->codecpar;
 601         const AVCodec *video_codec = avcodec_find_decoder(video_codecpar->codec_id);
 602
 603         video_timebase = format_ctx->streams[video_stream_index]->time_base;
 604         AVCodecContextWithDeleter video_codec_ctx = avcodec_alloc_context3_unique(nullptr);
 605         if (avcodec_parameters_to_context(video_codec_ctx.get(), video_codecpar) < 0) {
 606                 fprintf(stderr, "%s: Cannot fill video codec parameters\n", pathname.c_str());
 607                 return false;
 608         }
 609         if (video_codec == nullptr) {
 610                 fprintf(stderr, "%s: Cannot find video decoder\n", pathname.c_str());
 611                 return false;
 612         }
 613
 614         // Seemingly, it's not too easy to make something that just initializes
 615         // “whatever goes”, so we don't get CUDA or VULKAN or whatever here
 616         // without enumerating through several different types.
 617         // VA-API and VDPAU will do for now. We prioritize VDPAU for the
 618         // simple reason that there's a VA-API-via-VDPAU emulation for NVidia
 619         // cards that seems to work, but just hangs when trying to transfer the frame.
 620         //
 621         // Note that we don't actually check codec support beforehand,
 622         // so if you have a low-end VDPAU device but a high-end VA-API device,
 623         // you lose out on the extra codec support from the latter.
 624         AVBufferRef *hw_device_ctx = nullptr;
 625         if (av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VDPAU, nullptr, nullptr, 0) >= 0) {
 626                 video_codec_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 627                 video_codec_ctx->get_format = get_hw_format<AV_HWDEVICE_TYPE_VDPAU>;
 628         } else if (av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VAAPI, nullptr, nullptr, 0) >= 0) {
 629                 video_codec_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 630                 video_codec_ctx->get_format = get_hw_format<AV_HWDEVICE_TYPE_VAAPI>;
 631         } else {
 632                 fprintf(stderr, "Failed to initialize VA-API or VDPAU for FFmpeg acceleration. Decoding video in software.\n");
 633         }
 634
 635         if (avcodec_open2(video_codec_ctx.get(), video_codec, nullptr) < 0) {
 636                 fprintf(stderr, "%s: Cannot open video decoder\n", pathname.c_str());
 637                 return false;
 638         }
 639         unique_ptr<AVCodecContext, decltype(avcodec_close)*> video_codec_ctx_cleanup(
 640                 video_codec_ctx.get(), avcodec_close);
 641
 642         // Used in decode_ycbcr_format().
 643         is_mjpeg = video_codecpar->codec_id == AV_CODEC_ID_MJPEG;
 644
 645         // Open audio decoder, if we have audio.
 646         AVCodecContextWithDeleter audio_codec_ctx;
 647         if (audio_stream_index != -1) {
 648                 audio_codec_ctx = avcodec_alloc_context3_unique(nullptr);
 649                 const AVCodecParameters *audio_codecpar = format_ctx->streams[audio_stream_index]->codecpar;
 650                 audio_timebase = format_ctx->streams[audio_stream_index]->time_base;
 651                 if (avcodec_parameters_to_context(audio_codec_ctx.get(), audio_codecpar) < 0) {
 652                         fprintf(stderr, "%s: Cannot fill audio codec parameters\n", pathname.c_str());
 653                         return false;
 654                 }
 655                 const AVCodec *audio_codec = avcodec_find_decoder(audio_codecpar->codec_id);
 656                 if (audio_codec == nullptr) {
 657                         fprintf(stderr, "%s: Cannot find audio decoder\n", pathname.c_str());
 658                         return false;
 659                 }
 660                 if (avcodec_open2(audio_codec_ctx.get(), audio_codec, nullptr) < 0) {
 661                         fprintf(stderr, "%s: Cannot open audio decoder\n", pathname.c_str());
 662                         return false;
 663                 }
 664         }
 665         unique_ptr<AVCodecContext, decltype(avcodec_close)*> audio_codec_ctx_cleanup(
 666                 audio_codec_ctx.get(), avcodec_close);
 667
 668         internal_rewind();
 669
 670         // Main loop.
 671         bool first_frame = true;
 672         int consecutive_errors = 0;
 673         while (!producer_thread_should_quit.should_quit()) {
 674                 if (process_queued_commands(format_ctx.get(), pathname, last_modified, /*rewound=*/nullptr)) {
 675                         return true;
 676                 }
 677                 if (should_interrupt.load()) {
 678                         // Check as a failsafe, so that we don't need to rely on avio if we don't have to.
 679                         return false;
 680                 }
 681                 UniqueFrame audio_frame = audio_frame_allocator->alloc_frame();
 682                 AudioFormat audio_format;
 683
 684                 int64_t audio_pts;
 685                 bool error;
 686                 frame_timeout_started = steady_clock::now();
 687                 frame_timeout_valid = true;
 688                 AVFrameWithDeleter frame = decode_frame(format_ctx.get(), video_codec_ctx.get(), audio_codec_ctx.get(),
 689                         pathname, video_stream_index, audio_stream_index, subtitle_stream_index, audio_frame.get(), &audio_format, &audio_pts, &error);
 690                 frame_timeout_valid = false;
 691                 if (should_interrupt.load()) {
 692                         // Abort no matter whether we got a frame or not.
 693                         return false;
 694                 }
 695                 if (error) {
 696                         if (++consecutive_errors >= 100) {
 697                                 fprintf(stderr, "More than 100 consecutive error video frames, aborting playback.\n");
 698                                 return false;
 699                         } else {
 700                                 continue;
 701                         }
 702                 } else {
 703                         consecutive_errors = 0;
 704                 }
 705                 if (frame == nullptr) {
 706                         // EOF. Loop back to the start if we can.
 707                         if (format_ctx->pb != nullptr && format_ctx->pb->seekable == 0) {
 708                                 // Not seekable (but seemingly, sometimes av_seek_frame() would return 0 anyway,
 709                                 // so don't try).
 710                                 return true;
 711                         }
 712                         if (av_seek_frame(format_ctx.get(), /*stream_index=*/-1, /*timestamp=*/0, /*flags=*/0) < 0) {
 713                                 fprintf(stderr, "%s: Rewind failed, not looping.\n", pathname.c_str());
 714                                 return true;
 715                         }
 716                         if (video_codec_ctx != nullptr) {
 717                                 avcodec_flush_buffers(video_codec_ctx.get());
 718                         }
 719                         if (audio_codec_ctx != nullptr) {
 720                                 avcodec_flush_buffers(audio_codec_ctx.get());
 721                         }
 722                         // If the file has changed since last time, return to get it reloaded.
 723                         // Note that depending on how you move the file into place, you might
 724                         // end up corrupting the one you're already playing, so this path
 725                         // might not trigger.
 726                         if (changed_since(pathname, last_modified)) {
 727                                 return true;
 728                         }
 729                         internal_rewind();
 730                         continue;
 731                 }
 732
 733                 VideoFormat video_format = construct_video_format(frame.get(), video_timebase);
 734                 if (video_format.frame_rate_nom == 0 || video_format.frame_rate_den == 0) {
 735                         // Invalid frame rate; try constructing it from the previous frame length.
 736                         // (This is especially important if we are the master card, for SRT,
 737                         // since it affects audio. Not all senders have good timebases
 738                         // (e.g., Larix rounds first to timebase 1000 and then multiplies by
 739                         // 90 from there, it seems), but it's much better to have an oscillating
 740                         // value than just locking at 60.
 741                         if (last_pts != 0 && frame->pts > last_pts) {
 742                                 int64_t pts_diff = frame->pts - last_pts;
 743                                 video_format.frame_rate_nom = video_timebase.den;
 744                                 video_format.frame_rate_den = video_timebase.num * pts_diff;
 745                         } else {
 746                                 video_format.frame_rate_nom = 60;
 747                                 video_format.frame_rate_den = 1;
 748                         }
 749                 }
 750                 UniqueFrame video_frame = make_video_frame(frame.get(), pathname, &error);
 751                 if (error) {
 752                         return false;
 753                 }
 754
 755                 for ( ;; ) {
 756                         if (last_pts == 0 && pts_origin == 0) {
 757                                 pts_origin = frame->pts;
 758                         }
 759                         steady_clock::time_point now = steady_clock::now();
 760                         if (play_as_fast_as_possible) {
 761                                 video_frame->received_timestamp = now;
 762                                 audio_frame->received_timestamp = now;
 763                                 next_frame_start = now;
 764                         } else {
 765                                 next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
 766                                 if (first_frame && last_frame_was_connected) {
 767                                         // If reconnect took more than one second, this is probably a live feed,
 768                                         // and we should reset the resampler. (Or the rate is really, really low,
 769                                         // in which case a reset on the first frame is fine anyway.)
 770                                         if (duration<double>(next_frame_start - last_frame).count() >= 1.0) {
 771                                                 last_frame_was_connected = false;
 772                                         }
 773                                 }
 774                                 video_frame->received_timestamp = next_frame_start;
 775
 776                                 // The easiest way to get all the rate conversions etc. right is to move the
 777                                 // audio PTS into the video PTS timebase and go from there. (We'll get some
 778                                 // rounding issues, but they should not be a big problem.)
 779                                 int64_t audio_pts_as_video_pts = av_rescale_q(audio_pts, audio_timebase, video_timebase);
 780                                 audio_frame->received_timestamp = compute_frame_start(audio_pts_as_video_pts, pts_origin, video_timebase, start, rate);
 781
 782                                 if (audio_frame->len != 0) {
 783                                         // The received timestamps in Nageru are measured after we've just received the frame.
 784                                         // However, pts (especially audio pts) is at the _beginning_ of the frame.
 785                                         // If we have locked audio, the distinction doesn't really matter, as pts is
 786                                         // on a relative scale and a fixed offset is fine. But if we don't, we will have
 787                                         // a different number of samples each time, which will cause huge audio jitter
 788                                         // and throw off the resampler.
 789                                         //
 790                                         // In a sense, we should have compensated by adding the frame and audio lengths
 791                                         // to video_frame->received_timestamp and audio_frame->received_timestamp respectively,
 792                                         // but that would mean extra waiting in sleep_until(). All we need is that they
 793                                         // are correct relative to each other, though (and to the other frames we send),
 794                                         // so just align the end of the audio frame, and we're fine.
 795                                         size_t num_samples = (audio_frame->len * 8) / audio_format.bits_per_sample / audio_format.num_channels;
 796                                         double offset = double(num_samples) / OUTPUT_FREQUENCY -
 797                                                 double(video_format.frame_rate_den) / video_format.frame_rate_nom;
 798                                         audio_frame->received_timestamp += duration_cast<steady_clock::duration>(duration<double>(offset));
 799                                 }
 800
 801                                 if (duration<double>(now - next_frame_start).count() >= 0.1) {
 802                                         // If we don't have enough CPU to keep up, or if we have a live stream
 803                                         // where the initial origin was somehow wrong, we could be behind indefinitely.
 804                                         // In particular, this will give the audio resampler problems as it tries
 805                                         // to speed up to reduce the delay, hitting the low end of the buffer every time.
 806                                         fprintf(stderr, "%s: Playback %.0f ms behind, resetting time scale\n",
 807                                                 pathname.c_str(),
 808                                                 1e3 * duration<double>(now - next_frame_start).count());
 809                                         pts_origin = frame->pts;
 810                                         start = next_frame_start = now;
 811                                         timecode += TYPICAL_FPS * 2 + 1;
 812                                 }
 813                         }
 814                         bool finished_wakeup;
 815                         if (play_as_fast_as_possible) {
 816                                 finished_wakeup = !producer_thread_should_quit.should_quit();
 817                         } else {
 818                                 finished_wakeup = producer_thread_should_quit.sleep_until(next_frame_start);
 819                         }
 820                         if (finished_wakeup) {
 821                                 if (audio_frame->len > 0) {
 822                                         assert(audio_pts != -1);
 823                                 }
 824                                 if (!last_frame_was_connected) {
 825                                         // We're recovering from an error (or really slow load, see above).
 826                                         // Make sure to get the audio resampler reset. (This is a hack;
 827                                         // ideally, the frame callback should just accept a way to signal
 828                                         // audio discontinuity.)
 829                                         timecode += TYPICAL_FPS * 2 + 1;
 830                                 }
 831                                 last_neutral_color = get_neutral_color(frame->metadata);
 832                                 if (frame_callback != nullptr) {
 833                                         frame_callback(frame->pts, video_timebase, audio_pts, audio_timebase, timecode++,
 834                                                 video_frame.get_and_release(), 0, video_format,
 835                                                 audio_frame.get_and_release(), 0, audio_format);
 836                                 }
 837                                 first_frame = false;
 838                                 last_frame = steady_clock::now();
 839                                 last_frame_was_connected = true;
 840                                 break;
 841                         } else {
 842                                 if (producer_thread_should_quit.should_quit()) break;
 843
 844                                 bool rewound = false;
 845                                 if (process_queued_commands(format_ctx.get(), pathname, last_modified, &rewound)) {
 846                                         return true;
 847                                 }
 848                                 // If we just rewound, drop this frame on the floor and be done.
 849                                 if (rewound) {
 850                                         break;
 851                                 }
 852                                 // OK, we didn't, so probably a rate change. Recalculate next_frame_start,
 853                                 // but if it's now in the past, we'll reset the origin, so that we don't
 854                                 // generate a huge backlog of frames that we need to run through quickly.
 855                                 next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
 856                                 steady_clock::time_point now = steady_clock::now();
 857                                 if (next_frame_start < now) {
 858                                         pts_origin = frame->pts;
 859                                         start = next_frame_start = now;
 860                                 }
 861                         }
 862                 }
 863                 last_pts = frame->pts;
 864         }
 865         return true;
 866 }
 867
 868 void FFmpegCapture::internal_rewind()
 869 {
 870         pts_origin = last_pts = 0;
 871         start = next_frame_start = steady_clock::now();
 872 }
 873
 874 bool FFmpegCapture::process_queued_commands(AVFormatContext *format_ctx, const std::string &pathname, timespec last_modified, bool *rewound)
 875 {
 876         // Process any queued commands from other threads.
 877         vector<QueuedCommand> commands;
 878         {
 879                 lock_guard<mutex> lock(queue_mu);
 880                 swap(commands, command_queue);
 881         }
 882         for (const QueuedCommand &cmd : commands) {
 883                 switch (cmd.command) {
 884                 case QueuedCommand::REWIND:
 885                         if (av_seek_frame(format_ctx, /*stream_index=*/-1, /*timestamp=*/0, /*flags=*/0) < 0) {
 886                                 fprintf(stderr, "%s: Rewind failed, stopping play.\n", pathname.c_str());
 887                         }
 888                         // If the file has changed since last time, return to get it reloaded.
 889                         // Note that depending on how you move the file into place, you might
 890                         // end up corrupting the one you're already playing, so this path
 891                         // might not trigger.
 892                         if (changed_since(pathname, last_modified)) {
 893                                 return true;
 894                         }
 895                         internal_rewind();
 896                         if (rewound != nullptr) {
 897                                 *rewound = true;
 898                         }
 899                         break;
 900
 901                 case QueuedCommand::CHANGE_RATE:
 902                         // Change the origin to the last played frame.
 903                         start = compute_frame_start(last_pts, pts_origin, video_timebase, start, rate);
 904                         pts_origin = last_pts;
 905                         rate = cmd.new_rate;
 906                         play_as_fast_as_possible = (rate >= 10.0);
 907                         break;
 908                 }
 909         }
 910         return false;
 911 }
 912
 913 namespace {
 914
 915 }  // namespace
 916
 917 AVFrameWithDeleter FFmpegCapture::decode_frame(AVFormatContext *format_ctx, AVCodecContext *video_codec_ctx, AVCodecContext *audio_codec_ctx,
 918         const std::string &pathname, int video_stream_index, int audio_stream_index, int subtitle_stream_index,
 919         FrameAllocator::Frame *audio_frame, AudioFormat *audio_format, int64_t *audio_pts, bool *error)
 920 {
 921         *error = false;
 922
 923         // Read packets until we have a frame or there are none left.
 924         bool frame_finished = false;
 925         AVFrameWithDeleter audio_avframe = av_frame_alloc_unique();
 926         AVFrameWithDeleter video_avframe = av_frame_alloc_unique();
 927         bool eof = false;
 928         *audio_pts = -1;
 929         bool has_audio = false;
 930         do {
 931                 AVPacketWithDeleter pkt = av_packet_alloc_unique();
 932                 pkt->data = nullptr;
 933                 pkt->size = 0;
 934                 if (av_read_frame(format_ctx, pkt.get()) == 0) {
 935                         if (pkt->stream_index == audio_stream_index && audio_callback != nullptr) {
 936                                 audio_callback(pkt.get(), format_ctx->streams[audio_stream_index]->time_base);
 937                         }
 938                         if (pkt->stream_index == video_stream_index && video_callback != nullptr) {
 939                                 video_callback(pkt.get(), format_ctx->streams[video_stream_index]->time_base);
 940                         }
 941                         if (pkt->stream_index == video_stream_index && global_flags.transcode_video) {
 942                                 if (avcodec_send_packet(video_codec_ctx, pkt.get()) < 0) {
 943                                         fprintf(stderr, "%s: Cannot send packet to video codec.\n", pathname.c_str());
 944                                         *error = true;
 945                                         return AVFrameWithDeleter(nullptr);
 946                                 }
 947                         } else if (pkt->stream_index == audio_stream_index && global_flags.transcode_audio) {
 948                                 has_audio = true;
 949                                 if (avcodec_send_packet(audio_codec_ctx, pkt.get()) < 0) {
 950                                         fprintf(stderr, "%s: Cannot send packet to audio codec.\n", pathname.c_str());
 951                                         *error = true;
 952                                         return AVFrameWithDeleter(nullptr);
 953                                 }
 954                         } else if (pkt->stream_index == subtitle_stream_index) {
 955                                 last_subtitle = string(reinterpret_cast<const char *>(pkt->data), pkt->size);
 956                                 has_last_subtitle = true;
 957                         }
 958                 } else {
 959                         eof = true;  // Or error, but ignore that for the time being.
 960                 }
 961
 962                 // Decode audio, if any.
 963                 if (has_audio) {
 964                         for ( ;; ) {
 965                                 int err = avcodec_receive_frame(audio_codec_ctx, audio_avframe.get());
 966                                 if (err == 0) {
 967                                         if (*audio_pts == -1) {
 968                                                 *audio_pts = audio_avframe->pts;
 969                                         }
 970                                         convert_audio(audio_avframe.get(), audio_frame, audio_format);
 971                                 } else if (err == AVERROR(EAGAIN)) {
 972                                         break;
 973                                 } else {
 974                                         fprintf(stderr, "%s: Cannot receive frame from audio codec.\n", pathname.c_str());
 975                                         *error = true;
 976                                         return AVFrameWithDeleter(nullptr);
 977                                 }
 978                         }
 979                 }
 980
 981                 // Decode video, if we have a frame.
 982                 int err = avcodec_receive_frame(video_codec_ctx, video_avframe.get());
 983                 if (err == 0) {
 984                         if (video_avframe->format == AV_PIX_FMT_VAAPI ||
 985                             video_avframe->format == AV_PIX_FMT_VDPAU) {
 986                                 // Get the frame down to the CPU. (TODO: See if we can keep it
 987                                 // on the GPU all the way, since it will be going up again later.
 988                                 // However, this only works if the OpenGL GPU is the same one.)
 989                                 AVFrameWithDeleter sw_frame = av_frame_alloc_unique();
 990                                 int err = av_hwframe_transfer_data(sw_frame.get(), video_avframe.get(), 0);
 991                                 if (err != 0) {
 992                                         fprintf(stderr, "%s: Cannot transfer hardware video frame to software.\n", pathname.c_str());
 993                                         *error = true;
 994                                         return AVFrameWithDeleter(nullptr);
 995                                 }
 996                                 sw_frame->pts = video_avframe->pts;
 997                                 sw_frame->pkt_duration = video_avframe->pkt_duration;
 998                                 video_avframe = move(sw_frame);
 999                         }
1000                         frame_finished = true;
1001                         break;
1002                 } else if (err != AVERROR(EAGAIN)) {
1003                         fprintf(stderr, "%s: Cannot receive frame from video codec.\n", pathname.c_str());
1004                         *error = true;
1005                         return AVFrameWithDeleter(nullptr);
1006                 }
1007         } while (!eof);
1008
1009         if (frame_finished)
1010                 return video_avframe;
1011         else
1012                 return AVFrameWithDeleter(nullptr);
1013 }
1014
1015 void FFmpegCapture::convert_audio(const AVFrame *audio_avframe, FrameAllocator::Frame *audio_frame, AudioFormat *audio_format)
1016 {
1017         // Decide on a format. If there already is one in this audio frame,
1018         // we're pretty much forced to use it. If not, we try to find an exact match.
1019         // If that still doesn't work, we default to 32-bit signed chunked
1020         // (float would be nice, but there's really no way to signal that yet).
1021         AVSampleFormat dst_format;
1022         if (audio_format->bits_per_sample == 0) {
1023                 switch (audio_avframe->format) {
1024                 case AV_SAMPLE_FMT_S16:
1025                 case AV_SAMPLE_FMT_S16P:
1026                         audio_format->bits_per_sample = 16;
1027                         dst_format = AV_SAMPLE_FMT_S16;
1028                         break;
1029                 case AV_SAMPLE_FMT_S32:
1030                 case AV_SAMPLE_FMT_S32P:
1031                 default:
1032                         audio_format->bits_per_sample = 32;
1033                         dst_format = AV_SAMPLE_FMT_S32;
1034                         break;
1035                 }
1036         } else if (audio_format->bits_per_sample == 16) {
1037                 dst_format = AV_SAMPLE_FMT_S16;
1038         } else if (audio_format->bits_per_sample == 32) {
1039                 dst_format = AV_SAMPLE_FMT_S32;
1040         } else {
1041                 assert(false);
1042         }
1043         audio_format->num_channels = 2;
1044
1045         AVChannelLayout channel_layout = audio_avframe->ch_layout;
1046         if (!av_channel_layout_check(&channel_layout) ||
1047             channel_layout.order == AV_CHANNEL_ORDER_UNSPEC) {
1048                 av_channel_layout_default(&channel_layout, audio_avframe->ch_layout.nb_channels);
1049         }
1050
1051         if (resampler == nullptr ||
1052             audio_avframe->format != last_src_format ||
1053             dst_format != last_dst_format ||
1054             av_channel_layout_compare(&channel_layout, &last_channel_layout) !=  0||
1055             audio_avframe->sample_rate != last_sample_rate) {
1056                 // TODO: When we get C++20, use AV_CHANNEL_LAYOUT_STEREO_DOWNMIX.
1057                 AVChannelLayout stereo_downmix;
1058                 stereo_downmix.order = AV_CHANNEL_ORDER_NATIVE;
1059                 stereo_downmix.nb_channels = 2;
1060                 stereo_downmix.u.mask = AV_CH_LAYOUT_STEREO_DOWNMIX;
1061
1062                 swr_free(&resampler);
1063                 resampler = nullptr;
1064                 int err = swr_alloc_set_opts2(&resampler,
1065                                               /*out_ch_layout=*/&stereo_downmix,
1066                                               /*out_sample_fmt=*/dst_format,
1067                                               /*out_sample_rate=*/OUTPUT_FREQUENCY,
1068                                               /*in_ch_layout=*/&channel_layout,
1069                                               /*in_sample_fmt=*/AVSampleFormat(audio_avframe->format),
1070                                               /*in_sample_rate=*/audio_avframe->sample_rate,
1071                                               /*log_offset=*/0,
1072                                               /*log_ctx=*/nullptr);
1073
1074                 if (err != 0 || resampler == nullptr) {
1075                         fprintf(stderr, "Allocating resampler failed.\n");
1076                         abort();
1077                 }
1078
1079                 if (swr_init(resampler) < 0) {
1080                         fprintf(stderr, "Could not open resample context.\n");
1081                         abort();
1082                 }
1083
1084                 last_src_format = AVSampleFormat(audio_avframe->format);
1085                 last_dst_format = dst_format;
1086                 last_channel_layout = channel_layout;
1087                 last_sample_rate = audio_avframe->sample_rate;
1088         }
1089
1090         size_t bytes_per_sample = (audio_format->bits_per_sample / 8) * 2;
1091         size_t num_samples_room = (audio_frame->size - audio_frame->len) / bytes_per_sample;
1092
1093         uint8_t *data = audio_frame->data + audio_frame->len;
1094         int out_samples = swr_convert(resampler, &data, num_samples_room,
1095                 const_cast<const uint8_t **>(audio_avframe->data), audio_avframe->nb_samples);
1096         if (out_samples < 0) {
1097                 fprintf(stderr, "Audio conversion failed.\n");
1098                 abort();
1099         }
1100
1101         audio_frame->len += out_samples * bytes_per_sample;
1102 }
1103
1104 VideoFormat FFmpegCapture::construct_video_format(const AVFrame *frame, AVRational video_timebase)
1105 {
1106         VideoFormat video_format;
1107         video_format.width = frame_width(frame);
1108         video_format.height = frame_height(frame);
1109         if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
1110                 video_format.stride = frame_width(frame) * 4;
1111         } else if (pixel_format == FFmpegCapture::PixelFormat_NV12) {
1112                 video_format.stride = frame_width(frame);
1113         } else {
1114                 assert(pixel_format == bmusb::PixelFormat_8BitYCbCrPlanar);
1115                 video_format.stride = frame_width(frame);
1116         }
1117         video_format.frame_rate_nom = video_timebase.den;
1118         video_format.frame_rate_den = frame->pkt_duration * video_timebase.num;
1119         video_format.has_signal = true;
1120         video_format.is_connected = true;
1121         return video_format;
1122 }
1123
1124 UniqueFrame FFmpegCapture::make_video_frame(const AVFrame *frame, const string &pathname, bool *error)
1125 {
1126         *error = false;
1127
1128         UniqueFrame video_frame(video_frame_allocator->alloc_frame());
1129         if (video_frame->data == nullptr) {
1130                 return video_frame;
1131         }
1132
1133         if (sws_ctx == nullptr ||
1134             sws_last_width != frame->width ||
1135             sws_last_height != frame->height ||
1136             sws_last_src_format != frame->format) {
1137                 sws_dst_format = decide_dst_format(AVPixelFormat(frame->format), pixel_format);
1138                 sws_ctx.reset(
1139                         sws_getContext(frame->width, frame->height, AVPixelFormat(frame->format),
1140                                 frame_width(frame), frame_height(frame), sws_dst_format,
1141                                 SWS_BICUBIC, nullptr, nullptr, nullptr));
1142                 sws_last_width = frame->width;
1143                 sws_last_height = frame->height;
1144                 sws_last_src_format = frame->format;
1145         }
1146         if (sws_ctx == nullptr) {
1147                 fprintf(stderr, "%s: Could not create scaler context\n", pathname.c_str());
1148                 *error = true;
1149                 return video_frame;
1150         }
1151
1152         uint8_t *pic_data[4] = { nullptr, nullptr, nullptr, nullptr };
1153         int linesizes[4] = { 0, 0, 0, 0 };
1154         if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
1155                 pic_data[0] = video_frame->data;
1156                 linesizes[0] = frame_width(frame) * 4;
1157                 video_frame->len = (frame_width(frame) * 4) * frame_height(frame);
1158         } else if (pixel_format == PixelFormat_NV12) {
1159                 pic_data[0] = video_frame->data;
1160                 linesizes[0] = frame_width(frame);
1161
1162                 pic_data[1] = pic_data[0] + frame_width(frame) * frame_height(frame);
1163                 linesizes[1] = frame_width(frame);
1164
1165                 video_frame->len = (frame_width(frame) * 2) * frame_height(frame);
1166
1167                 const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(sws_dst_format);
1168                 current_frame_ycbcr_format = decode_ycbcr_format(desc, frame, is_mjpeg, &last_colorspace, &last_chroma_location);
1169         } else {
1170                 assert(pixel_format == bmusb::PixelFormat_8BitYCbCrPlanar);
1171                 const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(sws_dst_format);
1172
1173                 int chroma_width = AV_CEIL_RSHIFT(int(frame_width(frame)), desc->log2_chroma_w);
1174                 int chroma_height = AV_CEIL_RSHIFT(int(frame_height(frame)), desc->log2_chroma_h);
1175
1176                 pic_data[0] = video_frame->data;
1177                 linesizes[0] = frame_width(frame);
1178
1179                 pic_data[1] = pic_data[0] + frame_width(frame) * frame_height(frame);
1180                 linesizes[1] = chroma_width;
1181
1182                 pic_data[2] = pic_data[1] + chroma_width * chroma_height;
1183                 linesizes[2] = chroma_width;
1184
1185                 video_frame->len = frame_width(frame) * frame_height(frame) + 2 * chroma_width * chroma_height;
1186
1187                 current_frame_ycbcr_format = decode_ycbcr_format(desc, frame, is_mjpeg, &last_colorspace, &last_chroma_location);
1188         }
1189
1190         // FIXME: Currently, if the video is too high-res for one of the allocated
1191         // frames, we simply refuse to scale it here to avoid crashes. It would be better
1192         // if we could somehow signal getting larger frames, especially as 4K is a thing now.
1193         if (video_frame->len > FRAME_SIZE) {
1194                 fprintf(stderr, "%s: Decoded frame would be larger than supported FRAME_SIZE (%zu > %u), not decoding.\n", pathname.c_str(), video_frame->len, FRAME_SIZE);
1195                 *error = true;
1196                 return video_frame;
1197         }
1198
1199         sws_scale(sws_ctx.get(), frame->data, frame->linesize, 0, frame->height, pic_data, linesizes);
1200
1201         return video_frame;
1202 }
1203
1204 int FFmpegCapture::interrupt_cb_thunk(void *opaque)
1205 {
1206         return reinterpret_cast<FFmpegCapture *>(opaque)->interrupt_cb();
1207 }
1208
1209 int FFmpegCapture::interrupt_cb()
1210 {
1211         // If ten seconds is gone without anything happening, we assume that
1212         // we are in a network stream that died and FFmpeg just didn't
1213         // pick it up (or perhaps it just hung, keeping the connection open).
1214         // Called back approximately every 100 ms if something is hanging,
1215         // so we get more than enough accuracy for our purposes.
1216         if (!should_interrupt && frame_timeout_valid &&
1217             duration<double>(steady_clock::now() - frame_timeout_started).count() >= 10.0) {
1218                 string filename_copy;
1219                 {
1220                         lock_guard<mutex> lock(filename_mu);
1221                         filename_copy = filename;
1222                 }
1223                 fprintf(stderr, "%s: No frame for more than 10 seconds, restarting stream.\n", filename.c_str());
1224                 should_interrupt = true;
1225         }
1226         return should_interrupt.load();
1227 }
1228
1229 unsigned FFmpegCapture::frame_width(const AVFrame *frame) const
1230 {
1231         if (width == 0) {
1232                 return frame->width;
1233         } else {
1234                 return width;
1235         }
1236 }
1237
1238 unsigned FFmpegCapture::frame_height(const AVFrame *frame) const
1239 {
1240         if (height == 0) {
1241                 return frame->height;
1242         } else {
1243                 return height;
1244         }
1245 }
1246
1247 #ifdef HAVE_SRT
1248 int FFmpegCapture::read_srt_thunk(void *opaque, uint8_t *buf, int buf_size)
1249 {
1250         return reinterpret_cast<FFmpegCapture *>(opaque)->read_srt(buf, buf_size);
1251 }
1252
1253 int FFmpegCapture::read_srt(uint8_t *buf, int buf_size)
1254 {
1255         SRT_MSGCTRL mc = srt_msgctrl_default;
1256         return srt_recvmsg2(srt_sock, reinterpret_cast<char *>(buf), buf_size, &mc);
1257 }
1258 #endif