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• FFMPEG is really slow at extracting subtitles

  3 mars 2021, par Gustav P Svensson

  I'm trying to extract the subtitles from a 1080P video, around 40min long. I'm currently using this command (using fluent-ffmpeg in node, but the translated command is this) :

  


  ffmpeg -threads 3  -map 0: -c copy 


  


  This command takes about 20-30 min to complete. I've searched quite a lot on how to speed up this process, if I look at my task manager I can see that ffmpeg is using 0.1% of the CPU which makes me think that it's possible to speed up this process.

  


  I'm not sure if the -threads option is actually doing anything when extracting subtitles but I don't think it should make it slower atleast ?

  


  So my question is, is it possible to speed up this process ? I appriciate any help.

  


  Full FFMPEG log:
fmpeg version 3.4.8-0ubuntu0.2 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 7 (Ubuntu 7.5.0-3ubuntu1~18.04)
  configuration: --prefix=/usr --extra-version=0ubuntu0.2 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 78.100 / 55. 78.100
  libavcodec     57.107.100 / 57.107.100
  libavformat    57. 83.100 / 57. 83.100
  libavdevice    57. 10.100 / 57. 10.100
  libavfilter     6.107.100 /  6.107.100
  libavresample   3.  7.  0 /  3.  7.  0
  libswscale      4.  8.100 /  4.  8.100
  libswresample   2.  9.100 /  2.  9.100
  libpostproc    54.  7.100 / 54.  7.100
Input #0, matroska,webm, from '/home/test.mkv:
  Metadata:
    encoder         : libebml v1.3.6 + libmatroska v1.4.9
    creation_time   : 2019-03-14T16:46:55.000000Z
  Duration: 00:41:20.29, start: 0.000000, bitrate: 6430 kb/s
    Stream #0:0: Video: h264 (Main), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Metadata:
      BPS-eng         : 5788926
      DURATION-eng    : 00:41:20.020000000
      NUMBER_OF_FRAMES-eng: 59461
      NUMBER_OF_BYTES-eng: 1794581562
      _STATISTICS_WRITING_APP-eng: mkvmerge v31.0.0 ('Dolores In A Shoestand') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2019-03-14 16:46:55
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
    Stream #0:1(eng): Audio: eac3, 48000 Hz, 5.1(side), fltp, 640 kb/s (default)
    Metadata:
      title           : English
      BPS-eng         : 640000
      DURATION-eng    : 00:41:20.288000000
      NUMBER_OF_FRAMES-eng: 77509
      NUMBER_OF_BYTES-eng: 198423040
      _STATISTICS_WRITING_APP-eng: mkvmerge v31.0.0 ('Dolores In A Shoestand') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2019-03-14 16:46:55
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
    Stream #0:2(eng): Subtitle: subrip
    Metadata:
      BPS-eng         : 80
      DURATION-eng    : 00:40:22.295000000
      NUMBER_OF_FRAMES-eng: 645
      NUMBER_OF_BYTES-eng: 24473
      _STATISTICS_WRITING_APP-eng: mkvmerge v31.0.0 ('Dolores In A Shoestand') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2019-03-14 16:46:55
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
    Stream #0:3(eng): Subtitle: subrip
    Metadata:
      title           : SDH
      BPS-eng         : 86
      DURATION-eng    : 00:40:31.012000000
      NUMBER_OF_FRAMES-eng: 709
      NUMBER_OF_BYTES-eng: 26142
      _STATISTICS_WRITING_APP-eng: mkvmerge v31.0.0 ('Dolores In A Shoestand') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2019-03-14 16:46:55
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
Output #0, srt, to 'test6.srt':
  Metadata:
    encoder         : Lavf57.83.100
    Stream #0:0(eng): Subtitle: subrip
    Metadata:
      BPS-eng         : 80
      DURATION-eng    : 00:40:22.295000000
      NUMBER_OF_FRAMES-eng: 645
      NUMBER_OF_BYTES-eng: 24473
      _STATISTICS_WRITING_APP-eng: mkvmerge v31.0.0 ('Dolores In A Shoestand') 64-bit
      _STATISTICS_WRITING_DATE_UTC-eng: 2019-03-14 16:46:55
      _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES
Stream mapping:
  Stream #0:2 -> #0:0 (copy)
Press [q] to stop, [?] for help
size=      46kB time=00:40:36.68 bitrate=   0.2kbits/s speed=11.6x    
video:0kB audio:0kB subtitle:24kB other streams:0kB global headers:0kB muxing overhead: 94.438766%


  


• ffmpeg does not decode some h264 streams

  12 janvier 2016, par Andrey

  I have some ip of cameras on the local network.I receive video stream with live555 library (I took testRtspClient as a basis) and decode frames with ffmpeg (avcodec_decode_video2). Everything perfectly works.
  Problems begin when I try to decode a stream from an internet.

  The first problem - some packets lost, so defects appears. But it’s not a problem. Problem - after stop and start video stream it is necessary to wait for about 5 minutes of streaming before ffmpeg is able to decode something from the same ip camera. If packets doesn’t lost then everithing ok.

  The second problem - there is camera which sends video with resolution 2048х1538. The frame of such resolution is sent by several packets. live555 normally brings together them but when the frame is transferred to the decoder, the decoder returns the packet length, but got frame always 0.

  Here some my code :

  #define RECEIVE_BUFFER_SIZE 1000000
  
  AVCodecContext* avCodecContext; //definition
  
  AVFrame *frame;  //definition
  
  ...
  
  //init code
  
  _fReceiveBuffer = new uint8_t[RECEIVE_BUFFER_SIZE+512]; //buffer to receive frame
  
  ZeroMemory(_fReceiveBuffer, RECEIVE_BUFFER_SIZE + 512); //zeros
  
  _bufferSize = RECEIVE_BUFFER_SIZE * sizeof(uint8_t); //buffer size
  
  
  
  static const  uint8_t startCode[4] = { 0x00, 0x00, 0x00, 0x01 }; //this is for 0 0 0 1
  
  //before frame will transfer to decoder
  
  memcpy(_fReceiveBuffer, (void*)startCode, sizeof(uint8_t)* 4);
  
  _fReceiveBuffer += sizeof(sizeof(uint8_t)* 4);
  
  _bufferSize -= sizeof(sizeof(uint8_t)* 4);
  
  
  
  AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_H264); //find codec
  
  
  
  avCodecContext = avcodec_alloc_context3(codec); 
  
  avCodecContext->flags |= AV_PKT_FLAG_KEY;
  
  avcodec_open2(avCodecContext, codec, NULL);
  
  
  
  frame = av_frame_alloc();
  
  
  
  //frame
  
  void DummySink::afterGettingFrame(unsigned frameSize, unsigned numTruncatedBytes,
  
  struct timeval presentationTime, unsigned durationInMicroseconds) {
  
  
  
  if (strcmp(fSubsession.codecName(), "H264") == 0)
  
  {
  
      //code from onvif device manager
  
      static const uint8_t startCode3[] = { 0x00, 0x00, 0x01 };
  
      static const uint8_t startCode4[] = { 0x00, 0x00, 0x00, 0x01 };
  
      auto correctedFrameSize = frameSize;
  
      auto correctedBufferPtr = fPlObj->_fReceiveBuffer;
  
      if (frameSize < sizeof(startCode4) || memcmp(startCode4, correctedBufferPtr, sizeof(startCode4)) != 0){
  
          if (frameSize < sizeof(startCode3) || memcmp(startCode3, correctedBufferPtr, sizeof(startCode3)) != 0){
  
              correctedFrameSize += sizeof(uint8_t)* 4;
  
              correctedBufferPtr -= sizeof(uint8_t)* 4;
  
          }
  
      }
  
  
  
      ProcessFrame(correctedBufferPtr, correctedFrameSize, presentationTime, durationInMicroseconds);
  
  }
  
  continuePlaying();
  
  }
  
  
  
  void DummySink::ProcessFrame(unsigned char* framePtr, int frameSize, struct timeval presentationTime, unsigned duration)    {
  
  
  
  AVPacket avpkt;
  
  av_init_packet(&avpkt);
  
  avpkt.data = framePtr;
  
  avpkt.size = frameSize;
  
  while (avpkt.size > 0) {
  
      int got_frame = 0;
  
  
  
      int len = avcodec_decode_video2(avCodecContext, frame, &got_frame, &avpkt);
  
      if (len < 0) {
  
          //TODO: log error
  
          return;
  
      }
  
      else if (got_frame == 0)
  
      {
  
  //I tried this code, bacause "codecs which have the AV_CODEC_CAP_DELAY capability set have a delay between input and output"
  
  //but it didn't help
  
          /*AVPacket emptyPacket;
  
          av_init_packet(&emptyPacket);
  
          emptyPacket.data = NULL;
  
          emptyPacket.size = 0;
  
          emptyPacket.stream_index = avpkt.stream_index;
  
          len = avcodec_decode_video2(avCodecContext, frame, &got_frame, &emptyPacket);
  
          if ( got_frame == 1) goto next;*/
  
          return;
  
      }
  
  next:
  
      //... here code for view with DirectDraw - everithing ok with it
  
      avpkt.size -= len;
  
      avpkt.data += len;
  
  }
  
  }

  I alsa tried to send frame to decoder with sps and pps information :

  0 0 0 1 sps 0 0 0 1 pps 0 0 0 1 frame

  but it is not help.

  Interesting that avcodec_decode_video2 does not return frame with second problem (return all size of frame), but width and height in avCodecContext are set correctly. I can’t understart why it doesn’t return frame.

  Can anyone help with these problems ?

• Synchronizing RTSP signals with FFMPEG

  3 décembre 2019, par Taits

  I have achieved to merge two RTSP signals in one with FFMPEG but in the resulting stream, the first input has a delay of between 2 and 5 seconds with respect to the second. And it is always the first input that is delayed compared to the second.

  The two RTSP signals come from the same camera model, same configuration, same room ...

  However, if I put the same RTSP signal (either of the two) as input 1 and input 2, the same thing happens. Despite being the same signal, the first input is delayed compared to the second one.

  How could I get them synchronized ?

  This is the command that I execute :

  ffmpeg -rtsp_transport tcp -thread_queue_size 512 -rtbufsize 50M -r 15 
  
  -i rtsp://XXXX -rtsp_transport tcp -thread_queue_size 512 -rtbufsize 50M -r 15 
  
  -c:a aac -i rtsp://YYYY -filter_complex "[0:v]pad=iw*2:ih,setpts=PTS-STARTPTS[bg]; 
  
  [1:v]setpts=PTS-STARTPTS[fg]; [bg][fg]overlay=w[out]" -map "[out]" -f hls 
  
  -hls_time 2 -hls_list_size 5 -use_localtime 1 -use_localtime_mkdir 1 
  
  -hls_segment_filename 'LIVE/file-%s.ts' -map a -ar 16000 -ac 1 -ab 64000 -c:a aac 
  
  -y output.m3u8

  Here you have the process informationn :

  ffmpeg version 3.4.2 Copyright (c) 2000-2018 the FFmpeg developers 
  
  built with Apple LLVM version 9.0.0 (clang-900.0.39.2) 
  
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.4.2 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --disable-jack --enable-gpl --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma
  
    libavutil      55. 78.100 / 55. 78.100
  
    libavcodec     57.107.100 / 57.107.100
  
    libavformat    57. 83.100 / 57. 83.100
  
    libavdevice    57. 10.100 / 57. 10.100
  
    libavfilter     6.107.100 /  6.107.100
  
    libavresample   3.  7.  0 /  3.  7.  0
  
    libswscale      4.  8.100 /  4.  8.100
  
    libswresample   2.  9.100 /  2.  9.100
  
    libpostproc    54.  7.100 / 54.  7.100
  
  [rtsp @ 0x7fe284000e00] Missing PPS in sprop-parameter-sets, ignoring
  
  Input #0, rtsp, from 'rtsp://XXXX':
  
    Metadata:
  
      title           : Media Presentation
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: h264 (Main), yuv420p(progressive), 1280x720, 15 fps, 15 tbr, 90k tbn, 30 tbc
  
      Stream #0:1: Audio: aac (LC), 16000 Hz, mono, fltp
  
  [rtsp @ 0x7fe28484de00] Missing PPS in sprop-parameter-sets, ignoring
  
  Input #1, rtsp, from 'rtsp://XXXX':
  
    Metadata:
  
      title           : Media Presentation
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #1:0: Video: h264 (Main), yuv420p(progressive), 1280x720, 15 fps, 15 tbr, 90k tbn, 30 tbc
  
      Stream #1:1: Audio: aac (LC), 16000 Hz, mono, fltp
  
  Stream mapping:
  
    Stream #0:0 (h264) -> pad (graph 0)
  
    Stream #1:0 (h264) -> setpts (graph 0)
  
    overlay (graph 0) -> Stream #0:0 (libx264)
  
    Stream #0:1 -> #0:1 (aac (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x7fe286802000] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
  
  [libx264 @ 0x7fe286802000] profile High, level 4.0
  
  [libx264 @ 0x7fe286802000] 264 - core 152 r2854 e9a5903 - H.264/MPEG-4 AVC codec - Copyleft 2003-2017 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=1 weightp=2 keyint=250 keyint_min=15 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
  
  [hls @ 0x7fe286800000] Opening 'LIVE/file-1524728763.ts' for writing
  
  Output #0, hls, to 'output.m3u8':
  
    Metadata:
  
      title           : Media Presentation
  
      encoder         : Lavf57.83.100
  
      Stream #0:0: Video: h264 (libx264), yuv420p, 2560x720, q=-1--1, 15 fps, 90k tbn, 15 tbc (default)
  
      Metadata:
  
        encoder         : Lavc57.107.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
      Stream #0:1: Audio: aac (LC), 16000 Hz, mono, fltp, 64 kb/s
  
      Metadata:
  
        encoder         : Lavc57.107.100 aac
  
  [hls @ 0x7fe286800000] Opening 'LIVE/file-1524728782.ts' for writinged=1.09x    
  
  [hls @ 0x7fe286800000] Opening 'output.m3u8.tmp' for writing
  
  [hls @ 0x7fe286800000] Opening 'output.m3u8.tmp' for writing=N/A speed=1.07x    
  
  frame=  396 fps= 15 q=-1.0 Lsize=N/A time=00:00:27.00 bitrate=N/A speed=1.05x    
  
  video:2946kB audio:147kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown