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

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