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 <errno.h>
   7 #include <epoxy/egl.h>
   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 <time.h>
  17 #include <stdint.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <string>
  22 #include <sys/stat.h>
  23 #include <thread>
  24 #include <QSurface>
  25
  26 extern "C" {
  27 #include <libavcodec/avcodec.h>
  28 #include <libavcodec/codec.h>
  29 #include <libavcodec/codec_id.h>
  30 #include <libavcodec/codec_par.h>
  31 #include <libavformat/avformat.h>
  32 #include <libavutil/avutil.h>
  33 #include <libavutil/buffer.h>
  34 #include <libavutil/channel_layout.h>
  35 #include <libavutil/common.h>
  36 #include <libavutil/dict.h>
  37 #include <libavutil/error.h>
  38 #include <libavutil/frame.h>
  39 #include <libavutil/hwcontext.h>
  40 #include <libavutil/mathematics.h>
  41 #include <libavutil/pixdesc.h>
  42 #include <libavutil/pixfmt.h>
  43 #include <libavutil/rational.h>
  44 #include <libavutil/samplefmt.h>
  45 #include <libavutil/version.h>
  46 #include <libswresample/swresample.h>
  47 #include <libswscale/swscale.h>
  48 }
  49
  50 #include <chrono>
  51 #include <cstdint>
  52 #include <utility>
  53 #include <vector>
  54 #include <unordered_set>
  55
  56 #include <Eigen/Core>
  57 #include <Eigen/LU>
  58 #include <movit/colorspace_conversion_effect.h>
  59
  60 #include "bmusb/bmusb.h"
  61 #include "shared/context.h"
  62 #include "shared/ffmpeg_raii.h"
  63 #include "ffmpeg_util.h"
  64 #include "flags.h"
  65 #include "ref_counted_frame.h"
  66 #include "shared/timebase.h"
  67
  68 #ifdef HAVE_SRT
  69 #include <srt/srt.h>
  70 #endif
  71
  72 using namespace std;
  73 using namespace std::chrono;
  74 using namespace bmusb;
  75 using namespace movit;
  76 using namespace Eigen;
  77
  78 // Avoid deprecation warnings, but we don't want to drop FFmpeg 5.1 support just yet.
  79 #if LIBAVUTIL_VERSION_INT >= AV_VERSION_INT(57, 30, 100)
  80 #define pkt_duration duration
  81 #endif
  82
  83 namespace {
  84
  85 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)
  86 {
  87         const duration<double> pts((frame_pts - pts_origin) * double(video_timebase.num) / double(video_timebase.den));
  88         return origin + duration_cast<steady_clock::duration>(pts / rate);
  89 }
  90
  91 bool changed_since(const std::string &pathname, const timespec &ts)
  92 {
  93         if (ts.tv_sec < 0) {
  94                 return false;
  95         }
  96         struct stat buf;
  97         if (stat(pathname.c_str(), &buf) != 0) {
  98                 fprintf(stderr, "%s: Couldn't check for new version, leaving the old in place.\n", pathname.c_str());
  99                 return false;
 100         }
 101         return (buf.st_mtim.tv_sec != ts.tv_sec || buf.st_mtim.tv_nsec != ts.tv_nsec);
 102 }
 103
 104 bool is_full_range(const AVPixFmtDescriptor *desc)
 105 {
 106         // This is horrible, but there's no better way that I know of.
 107         return (strchr(desc->name, 'j') != nullptr);
 108 }
 109
 110 AVPixelFormat decide_dst_format(AVPixelFormat src_format, bmusb::PixelFormat dst_format_type)
 111 {
 112         if (dst_format_type == bmusb::PixelFormat_8BitBGRA) {
 113                 return AV_PIX_FMT_BGRA;
 114         }
 115         if (dst_format_type == FFmpegCapture::PixelFormat_NV12) {
 116                 return AV_PIX_FMT_NV12;
 117         }
 118
 119         assert(dst_format_type == bmusb::PixelFormat_8BitYCbCrPlanar);
 120
 121         // If this is a non-Y'CbCr format, just convert to 4:4:4 Y'CbCr
 122         // and be done with it. It's too strange to spend a lot of time on.
 123         // (Let's hope there's no alpha.)
 124         const AVPixFmtDescriptor *src_desc = av_pix_fmt_desc_get(src_format);
 125         if (src_desc == nullptr ||
 126             src_desc->nb_components != 3 ||
 127             (src_desc->flags & AV_PIX_FMT_FLAG_RGB)) {
 128                 return AV_PIX_FMT_YUV444P;
 129         }
 130
 131         // The best for us would be Cb and Cr together if possible,
 132         // but FFmpeg doesn't support that except in the special case of
 133         // NV12, so we need to go to planar even for the case of NV12.
 134         // Thus, look for the closest (but no worse) 8-bit planar Y'CbCr format
 135         // that matches in color range. (This will also include the case of
 136         // the source format already being acceptable.)
 137         bool src_full_range = is_full_range(src_desc);
 138         const char *best_format = "yuv444p";
 139         unsigned best_score = numeric_limits<unsigned>::max();
 140         for (const AVPixFmtDescriptor *desc = av_pix_fmt_desc_next(nullptr);
 141              desc;
 142              desc = av_pix_fmt_desc_next(desc)) {
 143                 // Find planar Y'CbCr formats only.
 144                 if (desc->nb_components != 3) continue;
 145                 if (desc->flags & AV_PIX_FMT_FLAG_RGB) continue;
 146                 if (!(desc->flags & AV_PIX_FMT_FLAG_PLANAR)) continue;
 147                 if (desc->comp[0].plane != 0 ||
 148                     desc->comp[1].plane != 1 ||
 149                     desc->comp[2].plane != 2) continue;
 150
 151                 // 8-bit formats only.
 152                 if (desc->flags & AV_PIX_FMT_FLAG_BE) continue;
 153                 if (desc->comp[0].depth != 8) continue;
 154
 155                 // Same or better chroma resolution only.
 156                 int chroma_w_diff = src_desc->log2_chroma_w - desc->log2_chroma_w;
 157                 int chroma_h_diff = src_desc->log2_chroma_h - desc->log2_chroma_h;
 158                 if (chroma_w_diff < 0 || chroma_h_diff < 0)
 159                         continue;
 160
 161                 // Matching full/limited range only.
 162                 if (is_full_range(desc) != src_full_range)
 163                         continue;
 164
 165                 // Pick something with as little excess chroma resolution as possible.
 166                 unsigned score = (1 << (chroma_w_diff)) << chroma_h_diff;
 167                 if (score < best_score) {
 168                         best_score = score;
 169                         best_format = desc->name;
 170                 }
 171         }
 172         return av_get_pix_fmt(best_format);
 173 }
 174
 175 YCbCrFormat decode_ycbcr_format(const AVPixFmtDescriptor *desc, const AVFrame *frame, bool is_mjpeg, AVColorSpace *last_colorspace, AVChromaLocation *last_chroma_location)
 176 {
 177         YCbCrFormat format;
 178         AVColorSpace colorspace = frame->colorspace;
 179         switch (colorspace) {
 180         case AVCOL_SPC_BT709:
 181                 format.luma_coefficients = YCBCR_REC_709;
 182                 break;
 183         case AVCOL_SPC_BT470BG:
 184         case AVCOL_SPC_SMPTE170M:
 185         case AVCOL_SPC_SMPTE240M:
 186                 format.luma_coefficients = YCBCR_REC_601;
 187                 break;
 188         case AVCOL_SPC_BT2020_NCL:
 189                 format.luma_coefficients = YCBCR_REC_2020;
 190                 break;
 191         case AVCOL_SPC_UNSPECIFIED:
 192                 format.luma_coefficients = (frame->height >= 720 ? YCBCR_REC_709 : YCBCR_REC_601);
 193                 break;
 194         default:
 195                 if (colorspace != *last_colorspace) {
 196                         fprintf(stderr, "Unknown Y'CbCr coefficient enum %d from FFmpeg; choosing Rec. 709.\n",
 197                                 colorspace);
 198                 }
 199                 format.luma_coefficients = YCBCR_REC_709;
 200                 break;
 201         }
 202         *last_colorspace = colorspace;
 203
 204         format.full_range = is_full_range(desc);
 205         format.num_levels = 1 << desc->comp[0].depth;
 206         format.chroma_subsampling_x = 1 << desc->log2_chroma_w;
 207         format.chroma_subsampling_y = 1 << desc->log2_chroma_h;
 208
 209         switch (frame->chroma_location) {
 210         case AVCHROMA_LOC_LEFT:
 211                 format.cb_x_position = 0.0;
 212                 format.cb_y_position = 0.5;
 213                 break;
 214         case AVCHROMA_LOC_CENTER:
 215                 format.cb_x_position = 0.5;
 216                 format.cb_y_position = 0.5;
 217                 break;
 218         case AVCHROMA_LOC_TOPLEFT:
 219                 format.cb_x_position = 0.0;
 220                 format.cb_y_position = 0.0;
 221                 break;
 222         case AVCHROMA_LOC_TOP:
 223                 format.cb_x_position = 0.5;
 224                 format.cb_y_position = 0.0;
 225                 break;
 226         case AVCHROMA_LOC_BOTTOMLEFT:
 227                 format.cb_x_position = 0.0;
 228                 format.cb_y_position = 1.0;
 229                 break;
 230         case AVCHROMA_LOC_BOTTOM:
 231                 format.cb_x_position = 0.5;
 232                 format.cb_y_position = 1.0;
 233                 break;
 234         default:
 235                 if (frame->chroma_location != *last_chroma_location) {
 236                         fprintf(stderr, "Unknown chroma location coefficient enum %d from FFmpeg; choosing center.\n",
 237                                 frame->chroma_location);
 238                 }
 239                 format.cb_x_position = 0.5;
 240                 format.cb_y_position = 0.5;
 241                 break;
 242         }
 243         *last_chroma_location = frame->chroma_location;
 244
 245         if (is_mjpeg && !format.full_range) {
 246                 // Limited-range MJPEG is only detected by FFmpeg whenever a special
 247                 // JPEG comment is set, which means that in practice, the stream is
 248                 // almost certainly generated by Futatabi. Override FFmpeg's forced
 249                 // MJPEG defaults (it disregards the values set in the mux) with what
 250                 // Futatabi sets.
 251                 format.luma_coefficients = YCBCR_REC_709;
 252                 format.cb_x_position = 0.0;
 253                 format.cb_y_position = 0.5;
 254         }
 255
 256         format.cr_x_position = format.cb_x_position;
 257         format.cr_y_position = format.cb_y_position;
 258         return format;
 259 }
 260
 261 RGBTriplet get_neutral_color(AVDictionary *metadata)
 262 {
 263         if (metadata == nullptr) {
 264                 return RGBTriplet(1.0f, 1.0f, 1.0f);
 265         }
 266         AVDictionaryEntry *entry = av_dict_get(metadata, "WhitePoint", nullptr, 0);
 267         if (entry == nullptr) {
 268                 return RGBTriplet(1.0f, 1.0f, 1.0f);
 269         }
 270
 271         unsigned x_nom, x_den, y_nom, y_den;
 272         if (sscanf(entry->value, " %u:%u , %u:%u", &x_nom, &x_den, &y_nom, &y_den) != 4) {
 273                 fprintf(stderr, "WARNING: Unable to parse white point '%s', using default white point\n", entry->value);
 274                 return RGBTriplet(1.0f, 1.0f, 1.0f);
 275         }
 276
 277         double x = double(x_nom) / x_den;
 278         double y = double(y_nom) / y_den;
 279         double z = 1.0 - x - y;
 280
 281         Matrix3d rgb_to_xyz_matrix = movit::ColorspaceConversionEffect::get_xyz_matrix(COLORSPACE_sRGB);
 282         Vector3d rgb = rgb_to_xyz_matrix.inverse() * Vector3d(x, y, z);
 283
 284         return RGBTriplet(rgb[0], rgb[1], rgb[2]);
 285 }
 286
 287 }  // namespace
 288
 289 FFmpegCapture::FFmpegCapture(const string &filename, unsigned width, unsigned height, QSurface *surface)
 290         : filename(filename), width(width), height(height), video_timebase{1, 1}, surface(surface)
 291 {
 292         description = "Video: " + filename;
 293
 294         last_frame = steady_clock::now();
 295
 296         avformat_network_init();  // In case someone wants this.
 297 }
 298
 299 #ifdef HAVE_SRT
 300 FFmpegCapture::FFmpegCapture(int srt_sock, const string &stream_id, QSurface *surface)
 301         : srt_sock(srt_sock),
 302           width(0),  // Don't resize; SRT streams typically have stable resolution, and should behave much like regular cards in general.
 303           height(0),
 304           pixel_format(bmusb::PixelFormat_8BitYCbCrPlanar),
 305           video_timebase{1, 1},
 306           surface(surface)
 307 {
 308         if (stream_id.empty()) {
 309                 description = "SRT stream";
 310         } else {
 311                 description = stream_id;
 312         }
 313         play_as_fast_as_possible = true;
 314         play_once = true;
 315         last_frame = steady_clock::now();
 316 }
 317 #endif
 318
 319 FFmpegCapture::~FFmpegCapture()
 320 {
 321         if (has_dequeue_callbacks) {
 322                 dequeue_cleanup_callback();
 323         }
 324         swr_free(&resampler);
 325 #ifdef HAVE_SRT
 326         if (srt_sock != -1) {
 327                 srt_close(srt_sock);
 328         }
 329 #endif
 330         delete surface;
 331 }
 332
 333 void FFmpegCapture::configure_card()
 334 {
 335         if (video_frame_allocator == nullptr) {
 336                 owned_video_frame_allocator.reset(new MallocFrameAllocator(FRAME_SIZE, NUM_QUEUED_VIDEO_FRAMES));
 337                 set_video_frame_allocator(owned_video_frame_allocator.get());
 338         }
 339         if (audio_frame_allocator == nullptr) {
 340                 // Audio can come out in pretty large chunks, so increase from the default 1 MB.
 341                 owned_audio_frame_allocator.reset(new MallocFrameAllocator(1 << 20, NUM_QUEUED_AUDIO_FRAMES));
 342                 set_audio_frame_allocator(owned_audio_frame_allocator.get());
 343         }
 344 }
 345
 346 void FFmpegCapture::start_bm_capture()
 347 {
 348         if (running) {
 349                 return;
 350         }
 351         running = true;
 352         producer_thread_should_quit.unquit();
 353         producer_thread = thread(&FFmpegCapture::producer_thread_func, this);
 354 }
 355
 356 void FFmpegCapture::stop_dequeue_thread()
 357 {
 358         if (!running) {
 359                 return;
 360         }
 361         running = false;
 362         producer_thread_should_quit.quit();
 363         producer_thread.join();
 364 }
 365
 366 std::map<uint32_t, VideoMode> FFmpegCapture::get_available_video_modes() const
 367 {
 368         // Note: This will never really be shown in the UI.
 369         VideoMode mode;
 370
 371         char buf[256];
 372         snprintf(buf, sizeof(buf), "%ux%u", sws_last_width, sws_last_height);
 373         mode.name = buf;
 374
 375         mode.autodetect = false;
 376         mode.width = sws_last_width;
 377         mode.height = sws_last_height;
 378         mode.frame_rate_num = 60;
 379         mode.frame_rate_den = 1;
 380         mode.interlaced = false;
 381
 382         return {{ 0, mode }};
 383 }
 384
 385 void FFmpegCapture::producer_thread_func()
 386 {
 387         char thread_name[16];
 388         snprintf(thread_name, sizeof(thread_name), "FFmpeg_C_%d", card_index);
 389         pthread_setname_np(pthread_self(), thread_name);
 390
 391         // We need a context in case create_frame() needs to reallocate something.
 392         // (If none is given, we are probably in Kaeru, which uses MallocFrameAllocator
 393         // anyway, which doesn't reallocate currently and definitely doesn't need
 394         // an active OpenGL context to do so.)
 395         QOpenGLContext *context = nullptr;
 396         if (surface != nullptr) {
 397                 context = create_context(this->surface);
 398                 eglBindAPI(EGL_OPENGL_API);
 399                 if (!make_current(context, this->surface)) {
 400                         printf("display=%p surface=%p context=%p curr=%p err=%d\n", eglGetCurrentDisplay(), this->surface, context, eglGetCurrentContext(),
 401                                 eglGetError());
 402                         abort();
 403                 }
 404         }
 405
 406         while (!producer_thread_should_quit.should_quit()) {
 407                 string filename_copy;
 408                 {
 409                         lock_guard<mutex> lock(filename_mu);
 410                         filename_copy = filename;
 411                 }
 412
 413                 string pathname;
 414                 if (srt_sock == -1) {
 415                         pathname = search_for_file(filename_copy);
 416                 } else {
 417                         pathname = description;
 418                 }
 419                 if (pathname.empty()) {
 420                         send_disconnected_frame();
 421                         if (play_once) {
 422                                 break;
 423                         }
 424                         producer_thread_should_quit.sleep_for(seconds(1));
 425                         fprintf(stderr, "%s not found, sleeping one second and trying again...\n", filename_copy.c_str());
 426                         continue;
 427                 }
 428                 should_interrupt = false;
 429                 if (!play_video(pathname)) {
 430                         // Error.
 431                         send_disconnected_frame();
 432                         if (play_once) {
 433                                 break;
 434                         }
 435                         fprintf(stderr, "Error when playing %s, sleeping one second and trying again...\n", pathname.c_str());
 436                         producer_thread_should_quit.sleep_for(seconds(1));
 437                         continue;
 438                 }
 439
 440                 if (play_once) {
 441                         send_disconnected_frame();
 442                         break;
 443                 }
 444
 445                 // Probably just EOF, will exit the loop above on next test.
 446         }
 447
 448         if (has_dequeue_callbacks) {
 449                 dequeue_cleanup_callback();
 450                 has_dequeue_callbacks = false;
 451         }
 452
 453         delete_context(context);
 454 }
 455
 456 void FFmpegCapture::send_disconnected_frame()
 457 {
 458         // Send an empty frame to signal that we have no signal anymore.
 459         FrameAllocator::Frame video_frame = video_frame_allocator->alloc_frame();
 460         size_t frame_width = width == 0 ? global_flags.width : width;
 461         size_t frame_height = height == 0 ? global_flags.height : height;
 462         if (video_frame.data) {
 463                 VideoFormat video_format;
 464                 video_format.width = frame_width;
 465                 video_format.height = frame_height;
 466                 video_format.frame_rate_nom = 60;
 467                 video_format.frame_rate_den = 1;
 468                 video_format.is_connected = false;
 469                 if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
 470                         video_format.stride = frame_width * 4;
 471                         video_frame.len = frame_width * frame_height * 4;
 472                         memset(video_frame.data, 0, video_frame.len);
 473                 } else {
 474                         video_format.stride = frame_width;
 475                         current_frame_ycbcr_format.luma_coefficients = YCBCR_REC_709;
 476                         current_frame_ycbcr_format.full_range = true;
 477                         current_frame_ycbcr_format.num_levels = 256;
 478                         current_frame_ycbcr_format.chroma_subsampling_x = 2;
 479                         current_frame_ycbcr_format.chroma_subsampling_y = 2;
 480                         current_frame_ycbcr_format.cb_x_position = 0.0f;
 481                         current_frame_ycbcr_format.cb_y_position = 0.0f;
 482                         current_frame_ycbcr_format.cr_x_position = 0.0f;
 483                         current_frame_ycbcr_format.cr_y_position = 0.0f;
 484                         video_frame.len = frame_width * frame_height * 2;
 485                         memset(video_frame.data, 0, frame_width * frame_height);
 486                         memset(video_frame.data + frame_width * frame_height, 128, frame_width * frame_height);  // Valid for both NV12 and planar.
 487                 }
 488
 489                 if (frame_callback != nullptr) {
 490                         frame_callback(-1, AVRational{1, TIMEBASE}, -1, AVRational{1, TIMEBASE}, timecode++,
 491                                 video_frame, /*video_offset=*/0, video_format,
 492                                 FrameAllocator::Frame(), /*audio_offset=*/0, AudioFormat());
 493                 }
 494                 last_frame_was_connected = false;
 495         }
 496
 497         if (play_once) {
 498                 disconnected = true;
 499                 if (card_disconnected_callback != nullptr) {
 500                         card_disconnected_callback();
 501                 }
 502         }
 503 }
 504
 505 template<AVHWDeviceType type>
 506 AVPixelFormat get_hw_format(AVCodecContext *ctx, const AVPixelFormat *fmt)
 507 {
 508         bool found_config_of_right_type = false;
 509         for (int i = 0;; ++i) {  // Termination condition inside loop.
 510                 const AVCodecHWConfig *config = avcodec_get_hw_config(ctx->codec, i);
 511                 if (config == nullptr) {  // End of list.
 512                         break;
 513                 }
 514                 if (!(config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX) ||
 515                     config->device_type != type) {
 516                         // Not interesting for us.
 517                         continue;
 518                 }
 519
 520                 // We have a config of the right type, but does it actually support
 521                 // the pixel format we want? (Seemingly, FFmpeg's way of signaling errors
 522                 // is to just replace the pixel format with a software-decoded one,
 523                 // such as yuv420p.)
 524                 found_config_of_right_type = true;
 525                 for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 526                         if (config->pix_fmt == *fmt_ptr) {
 527                                 fprintf(stderr, "Initialized '%s' hardware decoding for codec '%s'.\n",
 528                                         av_hwdevice_get_type_name(type), ctx->codec->name);
 529                                 if (ctx->profile == FF_PROFILE_H264_BASELINE) {
 530                                         fprintf(stderr, "WARNING: Stream claims to be H.264 Baseline, which is generally poorly supported in hardware decoders.\n");
 531                                         fprintf(stderr, "         Consider encoding it as Constrained Baseline, Main or High instead.\n");
 532                                         fprintf(stderr, "         Decoding might fail and fall back to software.\n");
 533                                 }
 534                                 return config->pix_fmt;
 535                         }
 536                 }
 537                 fprintf(stderr, "Decoder '%s' supports only these pixel formats:", ctx->codec->name);
 538                 unordered_set<AVPixelFormat> seen;
 539                 for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 540                         if (!seen.count(*fmt_ptr)) {
 541                                 fprintf(stderr, " %s", av_get_pix_fmt_name(*fmt_ptr));
 542                                 seen.insert(*fmt_ptr);
 543                         }
 544                 }
 545                 fprintf(stderr, " (wanted %s for hardware acceleration)\n", av_get_pix_fmt_name(config->pix_fmt));
 546
 547         }
 548
 549         if (!found_config_of_right_type) {
 550                 fprintf(stderr, "Decoder '%s' does not support device type '%s'.\n", ctx->codec->name, av_hwdevice_get_type_name(type));
 551         }
 552
 553         // We found no VA-API formats, so take the first software format.
 554         for (const AVPixelFormat *fmt_ptr = fmt; *fmt_ptr != -1; ++fmt_ptr) {
 555                 if ((av_pix_fmt_desc_get(*fmt_ptr)->flags & AV_PIX_FMT_FLAG_HWACCEL) == 0) {
 556                         fprintf(stderr, "Falling back to software format %s.\n", av_get_pix_fmt_name(*fmt_ptr));
 557                         return *fmt_ptr;
 558                 }
 559         }
 560
 561         // Fallback: Just return anything. (Should never really happen.)
 562         return fmt[0];
 563 }
 564
 565 bool FFmpegCapture::play_video(const string &pathname)
 566 {
 567         // Note: Call before open, not after; otherwise, there's a race.
 568         // (There is now, too, but it tips the correct way. We could use fstat()
 569         // if we had the file descriptor.)
 570         timespec last_modified;
 571         struct stat buf;
 572         if (stat(pathname.c_str(), &buf) != 0) {
 573                 // Probably some sort of protocol, so can't stat.
 574                 last_modified.tv_sec = -1;
 575         } else {
 576                 last_modified = buf.st_mtim;
 577         }
 578         last_colorspace = static_cast<AVColorSpace>(-1);
 579         last_chroma_location = static_cast<AVChromaLocation>(-1);
 580
 581         AVFormatContextWithCloser format_ctx;
 582         if (srt_sock == -1) {
 583                 // Regular file (or stream).
 584                 frame_timeout_started = steady_clock::now();
 585                 frame_timeout_valid = true;
 586                 format_ctx = avformat_open_input_unique(pathname.c_str(), /*fmt=*/nullptr,
 587                         /*options=*/nullptr,
 588                         AVIOInterruptCB{ &FFmpegCapture::interrupt_cb_thunk, this });
 589                 frame_timeout_valid = false;
 590         } else {
 591 #ifdef HAVE_SRT
 592                 // SRT socket, already opened.
 593                 const AVInputFormat *mpegts_fmt = av_find_input_format("mpegts");
 594                 format_ctx = avformat_open_input_unique(&FFmpegCapture::read_srt_thunk, this,
 595                         mpegts_fmt, /*options=*/nullptr,
 596                         AVIOInterruptCB{ &FFmpegCapture::interrupt_cb_thunk, this });
 597 #else
 598                 assert(false);
 599 #endif
 600         }
 601         if (format_ctx == nullptr) {
 602                 fprintf(stderr, "%s: Error opening file\n", pathname.c_str());
 603                 return false;
 604         }
 605
 606         if (avformat_find_stream_info(format_ctx.get(), nullptr) < 0) {
 607                 fprintf(stderr, "%s: Error finding stream info\n", pathname.c_str());
 608                 return false;
 609         }
 610
 611         int video_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_VIDEO);
 612         if (video_stream_index == -1) {
 613                 fprintf(stderr, "%s: No video stream found\n", pathname.c_str());
 614                 return false;
 615         }
 616
 617         int audio_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_AUDIO);
 618         int subtitle_stream_index = find_stream_index(format_ctx.get(), AVMEDIA_TYPE_SUBTITLE);
 619         has_last_subtitle = false;
 620
 621         // Open video decoder.
 622         const AVCodecParameters *video_codecpar = format_ctx->streams[video_stream_index]->codecpar;
 623         const AVCodec *video_codec = avcodec_find_decoder(video_codecpar->codec_id);
 624
 625         video_timebase = format_ctx->streams[video_stream_index]->time_base;
 626         AVCodecContextWithDeleter video_codec_ctx = avcodec_alloc_context3_unique(nullptr);
 627         if (avcodec_parameters_to_context(video_codec_ctx.get(), video_codecpar) < 0) {
 628                 fprintf(stderr, "%s: Cannot fill video codec parameters\n", pathname.c_str());
 629                 return false;
 630         }
 631         if (video_codec == nullptr) {
 632                 fprintf(stderr, "%s: Cannot find video decoder\n", pathname.c_str());
 633                 return false;
 634         }
 635
 636         // Seemingly, it's not too easy to make something that just initializes
 637         // “whatever goes”, so we don't get CUDA or VULKAN or whatever here
 638         // without enumerating through several different types.
 639         // VA-API and VDPAU will do for now. We prioritize VDPAU for the
 640         // simple reason that there's a VA-API-via-VDPAU emulation for NVidia
 641         // cards that seems to work, but just hangs when trying to transfer the frame.
 642         //
 643         // Note that we don't actually check codec support beforehand,
 644         // so if you have a low-end VDPAU device but a high-end VA-API device,
 645         // you lose out on the extra codec support from the latter.
 646         AVBufferRef *hw_device_ctx = nullptr;
 647         if (av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VDPAU, nullptr, nullptr, 0) >= 0) {
 648                 video_codec_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 649                 video_codec_ctx->get_format = get_hw_format<AV_HWDEVICE_TYPE_VDPAU>;
 650         } else if (av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VAAPI, nullptr, nullptr, 0) >= 0) {
 651                 video_codec_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
 652                 video_codec_ctx->get_format = get_hw_format<AV_HWDEVICE_TYPE_VAAPI>;
 653         } else {
 654                 fprintf(stderr, "Failed to initialize VA-API or VDPAU for FFmpeg acceleration. Decoding video in software.\n");
 655         }
 656
 657         if (avcodec_open2(video_codec_ctx.get(), video_codec, nullptr) < 0) {
 658                 fprintf(stderr, "%s: Cannot open video decoder\n", pathname.c_str());
 659                 return false;
 660         }
 661         unique_ptr<AVCodecContext, decltype(avcodec_close)*> video_codec_ctx_cleanup(
 662                 video_codec_ctx.get(), avcodec_close);
 663
 664         // Used in decode_ycbcr_format().
 665         is_mjpeg = video_codecpar->codec_id == AV_CODEC_ID_MJPEG;
 666
 667         // Open audio decoder, if we have audio.
 668         AVCodecContextWithDeleter audio_codec_ctx;
 669         if (audio_stream_index != -1) {
 670                 audio_codec_ctx = avcodec_alloc_context3_unique(nullptr);
 671                 const AVCodecParameters *audio_codecpar = format_ctx->streams[audio_stream_index]->codecpar;
 672                 audio_timebase = format_ctx->streams[audio_stream_index]->time_base;
 673                 if (avcodec_parameters_to_context(audio_codec_ctx.get(), audio_codecpar) < 0) {
 674                         fprintf(stderr, "%s: Cannot fill audio codec parameters\n", pathname.c_str());
 675                         return false;
 676                 }
 677                 const AVCodec *audio_codec = avcodec_find_decoder(audio_codecpar->codec_id);
 678                 if (audio_codec == nullptr) {
 679                         fprintf(stderr, "%s: Cannot find audio decoder\n", pathname.c_str());
 680                         return false;
 681                 }
 682                 if (avcodec_open2(audio_codec_ctx.get(), audio_codec, nullptr) < 0) {
 683                         fprintf(stderr, "%s: Cannot open audio decoder\n", pathname.c_str());
 684                         return false;
 685                 }
 686         }
 687         unique_ptr<AVCodecContext, decltype(avcodec_close)*> audio_codec_ctx_cleanup(
 688                 audio_codec_ctx.get(), avcodec_close);
 689
 690         internal_rewind();
 691
 692         // Main loop.
 693         bool first_frame = true;
 694         int consecutive_errors = 0;
 695         while (!producer_thread_should_quit.should_quit()) {
 696                 if (process_queued_commands(format_ctx.get(), pathname, last_modified, /*rewound=*/nullptr)) {
 697                         return true;
 698                 }
 699                 if (should_interrupt.load()) {
 700                         // Check as a failsafe, so that we don't need to rely on avio if we don't have to.
 701                         return false;
 702                 }
 703                 UniqueFrame audio_frame = audio_frame_allocator->alloc_frame();
 704                 AudioFormat audio_format;
 705
 706                 int64_t audio_pts;
 707                 bool error;
 708                 frame_timeout_started = steady_clock::now();
 709                 frame_timeout_valid = true;
 710                 AVFrameWithDeleter frame = decode_frame(format_ctx.get(), video_codec_ctx.get(), audio_codec_ctx.get(),
 711                         pathname, video_stream_index, audio_stream_index, subtitle_stream_index, audio_frame.get(), &audio_format, &audio_pts, &error);
 712                 frame_timeout_valid = false;
 713                 if (should_interrupt.load()) {
 714                         // Abort no matter whether we got a frame or not.
 715                         return false;
 716                 }
 717                 if (error) {
 718                         if (++consecutive_errors >= 100) {
 719                                 fprintf(stderr, "More than 100 consecutive error video frames, aborting playback.\n");
 720                                 return false;
 721                         } else {
 722                                 continue;
 723                         }
 724                 } else {
 725                         consecutive_errors = 0;
 726                 }
 727                 if (frame == nullptr) {
 728                         // EOF. Loop back to the start if we can.
 729                         if (format_ctx->pb != nullptr && format_ctx->pb->seekable == 0) {
 730                                 // Not seekable (but seemingly, sometimes av_seek_frame() would return 0 anyway,
 731                                 // so don't try).
 732                                 return true;
 733                         }
 734                         if (av_seek_frame(format_ctx.get(), /*stream_index=*/-1, /*timestamp=*/0, /*flags=*/0) < 0) {
 735                                 fprintf(stderr, "%s: Rewind failed, not looping.\n", pathname.c_str());
 736                                 return true;
 737                         }
 738                         if (video_codec_ctx != nullptr) {
 739                                 avcodec_flush_buffers(video_codec_ctx.get());
 740                         }
 741                         if (audio_codec_ctx != nullptr) {
 742                                 avcodec_flush_buffers(audio_codec_ctx.get());
 743                         }
 744                         // If the file has changed since last time, return to get it reloaded.
 745                         // Note that depending on how you move the file into place, you might
 746                         // end up corrupting the one you're already playing, so this path
 747                         // might not trigger.
 748                         if (changed_since(pathname, last_modified)) {
 749                                 return true;
 750                         }
 751                         internal_rewind();
 752                         continue;
 753                 }
 754
 755                 VideoFormat video_format = construct_video_format(frame.get(), video_timebase);
 756                 if (video_format.frame_rate_nom == 0 || video_format.frame_rate_den == 0) {
 757                         // Invalid frame rate; try constructing it from the previous frame length.
 758                         // (This is especially important if we are the master card, for SRT,
 759                         // since it affects audio. Not all senders have good timebases
 760                         // (e.g., Larix rounds first to timebase 1000 and then multiplies by
 761                         // 90 from there, it seems), but it's much better to have an oscillating
 762                         // value than just locking at 60.
 763                         if (last_pts != 0 && frame->pts > last_pts) {
 764                                 int64_t pts_diff = frame->pts - last_pts;
 765                                 video_format.frame_rate_nom = video_timebase.den;
 766                                 video_format.frame_rate_den = video_timebase.num * pts_diff;
 767                         } else {
 768                                 video_format.frame_rate_nom = 60;
 769                                 video_format.frame_rate_den = 1;
 770                         }
 771                 }
 772                 UniqueFrame video_frame = make_video_frame(frame.get(), pathname, &error);
 773                 if (error) {
 774                         return false;
 775                 }
 776
 777                 for ( ;; ) {
 778                         if (last_pts == 0 && pts_origin == 0) {
 779                                 pts_origin = frame->pts;
 780                         }
 781                         steady_clock::time_point now = steady_clock::now();
 782                         if (play_as_fast_as_possible) {
 783                                 video_frame->received_timestamp = now;
 784                                 audio_frame->received_timestamp = now;
 785                                 next_frame_start = now;
 786                         } else {
 787                                 next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
 788                                 if (first_frame && last_frame_was_connected) {
 789                                         // If reconnect took more than one second, this is probably a live feed,
 790                                         // and we should reset the resampler. (Or the rate is really, really low,
 791                                         // in which case a reset on the first frame is fine anyway.)
 792                                         if (duration<double>(next_frame_start - last_frame).count() >= 1.0) {
 793                                                 last_frame_was_connected = false;
 794                                         }
 795                                 }
 796                                 video_frame->received_timestamp = next_frame_start;
 797
 798                                 // The easiest way to get all the rate conversions etc. right is to move the
 799                                 // audio PTS into the video PTS timebase and go from there. (We'll get some
 800                                 // rounding issues, but they should not be a big problem.)
 801                                 int64_t audio_pts_as_video_pts = av_rescale_q(audio_pts, audio_timebase, video_timebase);
 802                                 audio_frame->received_timestamp = compute_frame_start(audio_pts_as_video_pts, pts_origin, video_timebase, start, rate);
 803
 804                                 if (audio_frame->len != 0) {
 805                                         // The received timestamps in Nageru are measured after we've just received the frame.
 806                                         // However, pts (especially audio pts) is at the _beginning_ of the frame.
 807                                         // If we have locked audio, the distinction doesn't really matter, as pts is
 808                                         // on a relative scale and a fixed offset is fine. But if we don't, we will have
 809                                         // a different number of samples each time, which will cause huge audio jitter
 810                                         // and throw off the resampler.
 811                                         //
 812                                         // In a sense, we should have compensated by adding the frame and audio lengths
 813                                         // to video_frame->received_timestamp and audio_frame->received_timestamp respectively,
 814                                         // but that would mean extra waiting in sleep_until(). All we need is that they
 815                                         // are correct relative to each other, though (and to the other frames we send),
 816                                         // so just align the end of the audio frame, and we're fine.
 817                                         size_t num_samples = (audio_frame->len * 8) / audio_format.bits_per_sample / audio_format.num_channels;
 818                                         double offset = double(num_samples) / OUTPUT_FREQUENCY -
 819                                                 double(video_format.frame_rate_den) / video_format.frame_rate_nom;
 820                                         audio_frame->received_timestamp += duration_cast<steady_clock::duration>(duration<double>(offset));
 821                                 }
 822
 823                                 if (duration<double>(now - next_frame_start).count() >= 0.1) {
 824                                         // If we don't have enough CPU to keep up, or if we have a live stream
 825                                         // where the initial origin was somehow wrong, we could be behind indefinitely.
 826                                         // In particular, this will give the audio resampler problems as it tries
 827                                         // to speed up to reduce the delay, hitting the low end of the buffer every time.
 828                                         fprintf(stderr, "%s: Playback %.0f ms behind, resetting time scale\n",
 829                                                 pathname.c_str(),
 830                                                 1e3 * duration<double>(now - next_frame_start).count());
 831                                         pts_origin = frame->pts;
 832                                         start = next_frame_start = now;
 833                                         timecode += TYPICAL_FPS * 2 + 1;
 834                                 }
 835                         }
 836                         bool finished_wakeup;
 837                         if (play_as_fast_as_possible) {
 838                                 finished_wakeup = !producer_thread_should_quit.should_quit();
 839                         } else {
 840                                 finished_wakeup = producer_thread_should_quit.sleep_until(next_frame_start);
 841                         }
 842                         if (finished_wakeup) {
 843                                 if (audio_frame->len > 0) {
 844                                         assert(audio_pts != -1);
 845                                 }
 846                                 if (!last_frame_was_connected) {
 847                                         // We're recovering from an error (or really slow load, see above).
 848                                         // Make sure to get the audio resampler reset. (This is a hack;
 849                                         // ideally, the frame callback should just accept a way to signal
 850                                         // audio discontinuity.)
 851                                         timecode += TYPICAL_FPS * 2 + 1;
 852                                 }
 853                                 last_neutral_color = get_neutral_color(frame->metadata);
 854                                 if (frame_callback != nullptr) {
 855                                         frame_callback(frame->pts, video_timebase, audio_pts, audio_timebase, timecode++,
 856                                                 video_frame.get_and_release(), 0, video_format,
 857                                                 audio_frame.get_and_release(), 0, audio_format);
 858                                 }
 859                                 first_frame = false;
 860                                 last_frame = steady_clock::now();
 861                                 last_frame_was_connected = true;
 862                                 break;
 863                         } else {
 864                                 if (producer_thread_should_quit.should_quit()) break;
 865
 866                                 bool rewound = false;
 867                                 if (process_queued_commands(format_ctx.get(), pathname, last_modified, &rewound)) {
 868                                         return true;
 869                                 }
 870                                 // If we just rewound, drop this frame on the floor and be done.
 871                                 if (rewound) {
 872                                         break;
 873                                 }
 874                                 // OK, we didn't, so probably a rate change. Recalculate next_frame_start,
 875                                 // but if it's now in the past, we'll reset the origin, so that we don't
 876                                 // generate a huge backlog of frames that we need to run through quickly.
 877                                 next_frame_start = compute_frame_start(frame->pts, pts_origin, video_timebase, start, rate);
 878                                 steady_clock::time_point now = steady_clock::now();
 879                                 if (next_frame_start < now) {
 880                                         pts_origin = frame->pts;
 881                                         start = next_frame_start = now;
 882                                 }
 883                         }
 884                 }
 885                 last_pts = frame->pts;
 886         }
 887         return true;
 888 }
 889
 890 void FFmpegCapture::internal_rewind()
 891 {
 892         pts_origin = last_pts = 0;
 893         start = next_frame_start = steady_clock::now();
 894 }
 895
 896 bool FFmpegCapture::process_queued_commands(AVFormatContext *format_ctx, const std::string &pathname, timespec last_modified, bool *rewound)
 897 {
 898         // Process any queued commands from other threads.
 899         vector<QueuedCommand> commands;
 900         {
 901                 lock_guard<mutex> lock(queue_mu);
 902                 swap(commands, command_queue);
 903         }
 904         for (const QueuedCommand &cmd : commands) {
 905                 switch (cmd.command) {
 906                 case QueuedCommand::REWIND:
 907                         if (av_seek_frame(format_ctx, /*stream_index=*/-1, /*timestamp=*/0, /*flags=*/0) < 0) {
 908                                 fprintf(stderr, "%s: Rewind failed, stopping play.\n", pathname.c_str());
 909                         }
 910                         // If the file has changed since last time, return to get it reloaded.
 911                         // Note that depending on how you move the file into place, you might
 912                         // end up corrupting the one you're already playing, so this path
 913                         // might not trigger.
 914                         if (changed_since(pathname, last_modified)) {
 915                                 return true;
 916                         }
 917                         internal_rewind();
 918                         if (rewound != nullptr) {
 919                                 *rewound = true;
 920                         }
 921                         break;
 922
 923                 case QueuedCommand::CHANGE_RATE:
 924                         // Change the origin to the last played frame.
 925                         start = compute_frame_start(last_pts, pts_origin, video_timebase, start, rate);
 926                         pts_origin = last_pts;
 927                         rate = cmd.new_rate;
 928                         play_as_fast_as_possible = (rate >= 10.0);
 929                         break;
 930                 }
 931         }
 932         return false;
 933 }
 934
 935 namespace {
 936
 937 }  // namespace
 938
 939 AVFrameWithDeleter FFmpegCapture::decode_frame(AVFormatContext *format_ctx, AVCodecContext *video_codec_ctx, AVCodecContext *audio_codec_ctx,
 940         const std::string &pathname, int video_stream_index, int audio_stream_index, int subtitle_stream_index,
 941         FrameAllocator::Frame *audio_frame, AudioFormat *audio_format, int64_t *audio_pts, bool *error)
 942 {
 943         *error = false;
 944
 945         // Read packets until we have a frame or there are none left.
 946         bool frame_finished = false;
 947         AVFrameWithDeleter audio_avframe = av_frame_alloc_unique();
 948         AVFrameWithDeleter video_avframe = av_frame_alloc_unique();
 949         bool eof = false;
 950         *audio_pts = -1;
 951         bool has_audio = false;
 952         do {
 953                 AVPacketWithDeleter pkt = av_packet_alloc_unique();
 954                 pkt->data = nullptr;
 955                 pkt->size = 0;
 956                 if (av_read_frame(format_ctx, pkt.get()) == 0) {
 957                         if (pkt->stream_index == audio_stream_index && audio_callback != nullptr) {
 958                                 audio_callback(pkt.get(), format_ctx->streams[audio_stream_index]->time_base);
 959                         }
 960                         if (pkt->stream_index == video_stream_index && video_callback != nullptr) {
 961                                 video_callback(pkt.get(), format_ctx->streams[video_stream_index]->time_base);
 962                         }
 963                         if (pkt->stream_index == video_stream_index && global_flags.transcode_video) {
 964                                 if (avcodec_send_packet(video_codec_ctx, pkt.get()) < 0) {
 965                                         fprintf(stderr, "%s: Cannot send packet to video codec.\n", pathname.c_str());
 966                                         *error = true;
 967                                         return AVFrameWithDeleter(nullptr);
 968                                 }
 969                         } else if (pkt->stream_index == audio_stream_index && global_flags.transcode_audio) {
 970                                 has_audio = true;
 971                                 if (avcodec_send_packet(audio_codec_ctx, pkt.get()) < 0) {
 972                                         fprintf(stderr, "%s: Cannot send packet to audio codec.\n", pathname.c_str());
 973                                         *error = true;
 974                                         return AVFrameWithDeleter(nullptr);
 975                                 }
 976                         } else if (pkt->stream_index == subtitle_stream_index) {
 977                                 last_subtitle = string(reinterpret_cast<const char *>(pkt->data), pkt->size);
 978                                 has_last_subtitle = true;
 979                         }
 980                 } else {
 981                         eof = true;  // Or error, but ignore that for the time being.
 982                 }
 983
 984                 // Decode audio, if any.
 985                 if (has_audio) {
 986                         for ( ;; ) {
 987                                 int err = avcodec_receive_frame(audio_codec_ctx, audio_avframe.get());
 988                                 if (err == 0) {
 989                                         if (*audio_pts == -1) {
 990                                                 *audio_pts = audio_avframe->pts;
 991                                         }
 992                                         convert_audio(audio_avframe.get(), audio_frame, audio_format);
 993                                 } else if (err == AVERROR(EAGAIN)) {
 994                                         break;
 995                                 } else {
 996                                         fprintf(stderr, "%s: Cannot receive frame from audio codec.\n", pathname.c_str());
 997                                         *error = true;
 998                                         return AVFrameWithDeleter(nullptr);
 999                                 }
1000                         }
1001                 }
1002
1003                 // Decode video, if we have a frame.
1004                 int err = avcodec_receive_frame(video_codec_ctx, video_avframe.get());
1005                 if (err == 0) {
1006                         if (video_avframe->format == AV_PIX_FMT_VAAPI ||
1007                             video_avframe->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                                 AVFrameWithDeleter sw_frame = av_frame_alloc_unique();
1012                                 int err = av_hwframe_transfer_data(sw_frame.get(), video_avframe.get(), 0);
1013                                 if (err != 0) {
1014                                         fprintf(stderr, "%s: Cannot transfer hardware video frame to software.\n", pathname.c_str());
1015                                         *error = true;
1016                                         return AVFrameWithDeleter(nullptr);
1017                                 }
1018                                 sw_frame->pts = video_avframe->pts;
1019                                 sw_frame->pkt_duration = video_avframe->pkt_duration;
1020                                 video_avframe = move(sw_frame);
1021                         }
1022                         frame_finished = true;
1023                         break;
1024                 } else if (err != AVERROR(EAGAIN)) {
1025                         fprintf(stderr, "%s: Cannot receive frame from video codec.\n", pathname.c_str());
1026                         *error = true;
1027                         return AVFrameWithDeleter(nullptr);
1028                 }
1029         } while (!eof);
1030
1031         if (frame_finished)
1032                 return video_avframe;
1033         else
1034                 return AVFrameWithDeleter(nullptr);
1035 }
1036
1037 void FFmpegCapture::convert_audio(const AVFrame *audio_avframe, FrameAllocator::Frame *audio_frame, AudioFormat *audio_format)
1038 {
1039         // Decide on a format. If there already is one in this audio frame,
1040         // we're pretty much forced to use it. If not, we try to find an exact match.
1041         // If that still doesn't work, we default to 32-bit signed chunked
1042         // (float would be nice, but there's really no way to signal that yet).
1043         AVSampleFormat dst_format;
1044         if (audio_format->bits_per_sample == 0) {
1045                 switch (audio_avframe->format) {
1046                 case AV_SAMPLE_FMT_S16:
1047                 case AV_SAMPLE_FMT_S16P:
1048                         audio_format->bits_per_sample = 16;
1049                         dst_format = AV_SAMPLE_FMT_S16;
1050                         break;
1051                 case AV_SAMPLE_FMT_S32:
1052                 case AV_SAMPLE_FMT_S32P:
1053                 default:
1054                         audio_format->bits_per_sample = 32;
1055                         dst_format = AV_SAMPLE_FMT_S32;
1056                         break;
1057                 }
1058         } else if (audio_format->bits_per_sample == 16) {
1059                 dst_format = AV_SAMPLE_FMT_S16;
1060         } else if (audio_format->bits_per_sample == 32) {
1061                 dst_format = AV_SAMPLE_FMT_S32;
1062         } else {
1063                 assert(false);
1064         }
1065         audio_format->num_channels = 2;
1066
1067         AVChannelLayout channel_layout = audio_avframe->ch_layout;
1068         if (!av_channel_layout_check(&channel_layout) ||
1069             channel_layout.order == AV_CHANNEL_ORDER_UNSPEC) {
1070                 av_channel_layout_default(&channel_layout, audio_avframe->ch_layout.nb_channels);
1071         }
1072
1073         if (resampler == nullptr ||
1074             audio_avframe->format != last_src_format ||
1075             dst_format != last_dst_format ||
1076             av_channel_layout_compare(&channel_layout, &last_channel_layout) !=  0||
1077             audio_avframe->sample_rate != last_sample_rate) {
1078                 // TODO: When we get C++20, use AV_CHANNEL_LAYOUT_STEREO_DOWNMIX.
1079                 AVChannelLayout stereo_downmix;
1080                 stereo_downmix.order = AV_CHANNEL_ORDER_NATIVE;
1081                 stereo_downmix.nb_channels = 2;
1082                 stereo_downmix.u.mask = AV_CH_LAYOUT_STEREO_DOWNMIX;
1083
1084                 swr_free(&resampler);
1085                 resampler = nullptr;
1086                 int err = swr_alloc_set_opts2(&resampler,
1087                                               /*out_ch_layout=*/&stereo_downmix,
1088                                               /*out_sample_fmt=*/dst_format,
1089                                               /*out_sample_rate=*/OUTPUT_FREQUENCY,
1090                                               /*in_ch_layout=*/&channel_layout,
1091                                               /*in_sample_fmt=*/AVSampleFormat(audio_avframe->format),
1092                                               /*in_sample_rate=*/audio_avframe->sample_rate,
1093                                               /*log_offset=*/0,
1094                                               /*log_ctx=*/nullptr);
1095
1096                 if (err != 0 || resampler == nullptr) {
1097                         fprintf(stderr, "Allocating resampler failed.\n");
1098                         abort();
1099                 }
1100
1101                 if (swr_init(resampler) < 0) {
1102                         fprintf(stderr, "Could not open resample context.\n");
1103                         abort();
1104                 }
1105
1106                 last_src_format = AVSampleFormat(audio_avframe->format);
1107                 last_dst_format = dst_format;
1108                 last_channel_layout = channel_layout;
1109                 last_sample_rate = audio_avframe->sample_rate;
1110         }
1111
1112         size_t bytes_per_sample = (audio_format->bits_per_sample / 8) * 2;
1113         size_t num_samples_room = (audio_frame->size - audio_frame->len) / bytes_per_sample;
1114
1115         uint8_t *data = audio_frame->data + audio_frame->len;
1116         int out_samples = swr_convert(resampler, &data, num_samples_room,
1117                 const_cast<const uint8_t **>(audio_avframe->data), audio_avframe->nb_samples);
1118         if (out_samples < 0) {
1119                 fprintf(stderr, "Audio conversion failed.\n");
1120                 abort();
1121         }
1122
1123         audio_frame->len += out_samples * bytes_per_sample;
1124 }
1125
1126 VideoFormat FFmpegCapture::construct_video_format(const AVFrame *frame, AVRational video_timebase)
1127 {
1128         VideoFormat video_format;
1129         video_format.width = frame_width(frame);
1130         video_format.height = frame_height(frame);
1131         if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
1132                 video_format.stride = frame_width(frame) * 4;
1133         } else if (pixel_format == FFmpegCapture::PixelFormat_NV12) {
1134                 video_format.stride = frame_width(frame);
1135         } else {
1136                 assert(pixel_format == bmusb::PixelFormat_8BitYCbCrPlanar);
1137                 video_format.stride = frame_width(frame);
1138         }
1139         video_format.frame_rate_nom = video_timebase.den;
1140         video_format.frame_rate_den = frame->pkt_duration * video_timebase.num;
1141         video_format.has_signal = true;
1142         video_format.is_connected = true;
1143         return video_format;
1144 }
1145
1146 UniqueFrame FFmpegCapture::make_video_frame(const AVFrame *frame, const string &pathname, bool *error)
1147 {
1148         *error = false;
1149
1150         UniqueFrame video_frame(video_frame_allocator->create_frame(frame->width, frame->height, frame->width));
1151         if (video_frame->data == nullptr) {
1152                 return video_frame;
1153         }
1154
1155         if (sws_ctx == nullptr ||
1156             sws_last_width != frame->width ||
1157             sws_last_height != frame->height ||
1158             sws_last_src_format != frame->format) {
1159                 sws_dst_format = decide_dst_format(AVPixelFormat(frame->format), pixel_format);
1160                 sws_ctx.reset(
1161                         sws_getContext(frame->width, frame->height, AVPixelFormat(frame->format),
1162                                 frame_width(frame), frame_height(frame), sws_dst_format,
1163                                 SWS_BICUBIC, nullptr, nullptr, nullptr));
1164                 sws_last_width = frame->width;
1165                 sws_last_height = frame->height;
1166                 sws_last_src_format = frame->format;
1167         }
1168         if (sws_ctx == nullptr) {
1169                 fprintf(stderr, "%s: Could not create scaler context\n", pathname.c_str());
1170                 *error = true;
1171                 return video_frame;
1172         }
1173
1174         uint8_t *pic_data[4] = { nullptr, nullptr, nullptr, nullptr };
1175         int linesizes[4] = { 0, 0, 0, 0 };
1176         if (pixel_format == bmusb::PixelFormat_8BitBGRA) {
1177                 pic_data[0] = video_frame->data;
1178                 linesizes[0] = frame_width(frame) * 4;
1179                 video_frame->len = (frame_width(frame) * 4) * frame_height(frame);
1180         } else if (pixel_format == PixelFormat_NV12) {
1181                 pic_data[0] = video_frame->data;
1182                 linesizes[0] = frame_width(frame);
1183
1184                 pic_data[1] = pic_data[0] + frame_width(frame) * frame_height(frame);
1185                 linesizes[1] = frame_width(frame);
1186
1187                 video_frame->len = (frame_width(frame) * 2) * frame_height(frame);
1188
1189                 const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(sws_dst_format);
1190                 current_frame_ycbcr_format = decode_ycbcr_format(desc, frame, is_mjpeg, &last_colorspace, &last_chroma_location);
1191         } else {
1192                 assert(pixel_format == bmusb::PixelFormat_8BitYCbCrPlanar);
1193                 const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(sws_dst_format);
1194
1195                 int chroma_width = AV_CEIL_RSHIFT(int(frame_width(frame)), desc->log2_chroma_w);
1196                 int chroma_height = AV_CEIL_RSHIFT(int(frame_height(frame)), desc->log2_chroma_h);
1197
1198                 pic_data[0] = video_frame->data;
1199                 linesizes[0] = frame_width(frame);
1200
1201                 pic_data[1] = pic_data[0] + frame_width(frame) * frame_height(frame);
1202                 linesizes[1] = chroma_width;
1203
1204                 pic_data[2] = pic_data[1] + chroma_width * chroma_height;
1205                 linesizes[2] = chroma_width;
1206
1207                 video_frame->len = frame_width(frame) * frame_height(frame) + 2 * chroma_width * chroma_height;
1208
1209                 current_frame_ycbcr_format = decode_ycbcr_format(desc, frame, is_mjpeg, &last_colorspace, &last_chroma_location);
1210         }
1211
1212         // FIXME: Currently, if the video is too high-res for one of the allocated
1213         // frames, we simply refuse to scale it here to avoid crashes. It would be better
1214         // if we could somehow signal getting larger frames, especially as 4K is a thing now.
1215         if (video_frame->len > video_frame->size) {
1216                 fprintf(stderr, "%s: Decoded frame would be larger than supported frame size (%zu > %zu), not decoding.\n", pathname.c_str(), video_frame->len, video_frame->size);
1217                 *error = true;
1218                 return video_frame;
1219         }
1220
1221         sws_scale(sws_ctx.get(), frame->data, frame->linesize, 0, frame->height, pic_data, linesizes);
1222
1223         return video_frame;
1224 }
1225
1226 int FFmpegCapture::interrupt_cb_thunk(void *opaque)
1227 {
1228         return reinterpret_cast<FFmpegCapture *>(opaque)->interrupt_cb();
1229 }
1230
1231 int FFmpegCapture::interrupt_cb()
1232 {
1233         // If ten seconds is gone without anything happening, we assume that
1234         // we are in a network stream that died and FFmpeg just didn't
1235         // pick it up (or perhaps it just hung, keeping the connection open).
1236         // Called back approximately every 100 ms if something is hanging,
1237         // so we get more than enough accuracy for our purposes.
1238         if (!should_interrupt && frame_timeout_valid &&
1239             duration<double>(steady_clock::now() - frame_timeout_started).count() >= 10.0) {
1240                 string filename_copy;
1241                 {
1242                         lock_guard<mutex> lock(filename_mu);
1243                         filename_copy = filename;
1244                 }
1245                 fprintf(stderr, "%s: No frame for more than 10 seconds, restarting stream.\n", filename.c_str());
1246                 should_interrupt = true;
1247         }
1248         return should_interrupt.load();
1249 }
1250
1251 unsigned FFmpegCapture::frame_width(const AVFrame *frame) const
1252 {
1253         if (width == 0) {
1254                 return frame->width;
1255         } else {
1256                 return width;
1257         }
1258 }
1259
1260 unsigned FFmpegCapture::frame_height(const AVFrame *frame) const
1261 {
1262         if (height == 0) {
1263                 return frame->height;
1264         } else {
1265                 return height;
1266         }
1267 }
1268
1269 #ifdef HAVE_SRT
1270 int FFmpegCapture::read_srt_thunk(void *opaque, uint8_t *buf, int buf_size)
1271 {
1272         return reinterpret_cast<FFmpegCapture *>(opaque)->read_srt(buf, buf_size);
1273 }
1274
1275 int FFmpegCapture::read_srt(uint8_t *buf, int buf_size)
1276 {
1277         SRT_MSGCTRL mc = srt_msgctrl_default;
1278         return srt_recvmsg2(srt_sock, reinterpret_cast<char *>(buf), buf_size, &mc);
1279 }
1280 #endif