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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%


  


• Output black when I decode h264 720p with ffmpeg

  6 décembre 2017, par José Marqueses Saxo

  First, sorry for my english. When I decode h264 720p in ardrone2.0 my output is black and I cant see anything.

  I have try to change the value of pCodecCtx->pix_fmt = AV_PIX_FMT_BGR24; to pCodecCtx->pix_fmt = AV_PIX_FMT_YUV420P; and the value of pCodecCtxH264->pix_fmt = AV_PIX_FMT_BGR24; to pCodecCtxH264->pix_fmt = AV_PIX_FMT_YUV420P; but my program crash. What am I doing wrong ?. Thank you, see part of my code :

  av_register_all();
  
  avcodec_register_all();
  
  avformat_network_init();
  
  
  
  // 1.2. Open video file
  
  if(avformat_open_input(&pFormatCtx, drone_addr, NULL, NULL) != 0) {
  
    mexPrintf("No conecct with Drone");
  
    EndVideo();
  
    return;
  
  }
  
  
  
  pCodec    = avcodec_find_decoder(AV_CODEC_ID_H264);
  
  
  
  pCodecCtx = avcodec_alloc_context3(pCodec);
  
  pCodecCtx->pix_fmt = AV_PIX_FMT_BGR24;
  
  pCodecCtx->skip_frame = AVDISCARD_DEFAULT;
  
  pCodecCtx->error_concealment = FF_EC_GUESS_MVS | FF_EC_DEBLOCK;
  
  pCodecCtx->err_recognition = AV_EF_CAREFUL;
  
  pCodecCtx->skip_loop_filter = AVDISCARD_DEFAULT;
  
  pCodecCtx->workaround_bugs = FF_BUG_AUTODETECT;
  
  pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
  
  pCodecCtx->codec_id = AV_CODEC_ID_H264;
  
  pCodecCtx->skip_idct = AVDISCARD_DEFAULT;
  
  pCodecCtx->width = 1280;
  
  pCodecCtx->height = 720;
  
  
  
  pCodecH264 = avcodec_find_decoder(AV_CODEC_ID_H264);
  
  pCodecCtxH264 = avcodec_alloc_context3(pCodecH264);
  
  
  
  
  
  pCodecCtxH264->pix_fmt = AV_PIX_FMT_BGR24;
  
  pCodecCtxH264->skip_frame = AVDISCARD_DEFAULT;
  
  pCodecCtxH264->error_concealment = FF_EC_GUESS_MVS | FF_EC_DEBLOCK;
  
  pCodecCtxH264->err_recognition = AV_EF_CAREFUL;
  
  pCodecCtxH264->skip_loop_filter = AVDISCARD_DEFAULT;
  
  pCodecCtxH264->workaround_bugs = FF_BUG_AUTODETECT;
  
  pCodecCtxH264->codec_type = AVMEDIA_TYPE_VIDEO;
  
  pCodecCtxH264->codec_id = AV_CODEC_ID_H264;
  
  pCodecCtxH264->skip_idct = AVDISCARD_DEFAULT;
  
  
  
  if(avcodec_open2(pCodecCtxH264, pCodecH264, &optionsDict) < 0)
  
  {
  
     mexPrintf("Error opening H264 codec");
  
     return ;
  
  }
  
  
  
  pFrame_BGR24 = av_frame_alloc();
  
  
  
  
  
  if(pFrame_BGR24 == NULL) {
  
     mexPrintf("Could not allocate pFrame_BGR24\n");
  
     return ;
  
  }
  
  
  
  // Determine required buffer size and allocate buffer
  
  
  
  buffer_BGR24 = 
  
  (uint8_t *)av_mallocz(av_image_get_buffer_size(AV_PIX_FMT_BGR24, 
  
  pCodecCtx->width, ((pCodecCtx->height == 720) ? 720 : pCodecCtx->height) * 
  
  sizeof(uint8_t)*3,1));
  
  
  
  // Assign buffer to image planes
  
  
  
  av_image_fill_arrays(pFrame_BGR24->data, pFrame_BGR24->linesize,
  
  buffer_BGR24,AV_PIX_FMT_BGR24, pCodecCtx->width, pCodecCtx->height,1);
  
  
  
  // format conversion context
  
  pConvertCtx_BGR24 = sws_getContext(pCodecCtx->width, pCodecCtx->height, 
  
  pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,  AV_PIX_FMT_BGR24, 
  
                                   SWS_BILINEAR | SWS_ACCURATE_RND, 0, 0, 0);
  
  
  
  // 1.6. get video frames
  
  pFrame = av_frame_alloc();
  
  
  
  av_init_packet(&packet);
  
  packet.data = NULL;
  
  packet.size = 0;
  
  }
  
  
  
  //Captura un frame
  
  void video::capture(mxArray *plhs[]) {
  
  
  
    if(av_read_frame(pFormatCtx, &packet) < 0){
  
        mexPrintf("Error al leer frame");
  
        return;
  
    }
  
     do {
  
         do {
  
            rest = avcodec_send_packet(pCodecCtxH264, &packet);
  
         } while(rest == AVERROR(EAGAIN));
  
  
  
         if(rest == AVERROR_EOF || rest == AVERROR(EINVAL)) {
  
                  printf("AVERROR(EAGAIN): %d, AVERROR_EOF: %d, 
  
                  AVERROR(EINVAL): %d\n", AVERROR(EAGAIN), AVERROR_EOF, 
  
                  AVERROR(EINVAL));
  
              printf("fe_read_frame: Frame getting error (%d)!\n", rest);
  
              return;
  
         }
  
  
  
         rest = avcodec_receive_frame(pCodecCtxH264, pFrame);
  
     } while(rest == AVERROR(EAGAIN));
  
  
  
     if(rest == AVERROR_EOF || rest == AVERROR(EINVAL)) {
  
  
  
      // An error or EOF occured,index break out and return what
  
      // we have so far.
  
        printf("AVERROR(EAGAIN): %d, AVERROR_EOF: %d, AVERROR(EINVAL): %d\n", 
  
        AVERROR(EAGAIN), AVERROR_EOF, AVERROR(EINVAL));
  
          printf("fe_read_frame: EOF or some othere decoding error (%d)!\n", 
  
          rest);
  
          return;
  
     }
  
  
  
  
  
     // 2.1.1. convert frame to GRAYSCALE [or BGR] for OpenCV
  
     sws_scale(pConvertCtx_BGR24,   (const uint8_t* const*)pFrame->data, 
  
         pFrame->linesize, 0,pCodecCtx->height,   pFrame_BGR24->data,   
  
               pFrame_BGR24->linesize);
  
  //}
  
     av_packet_unref(&packet);
  
     av_init_packet(&packet);
  
     mwSize dims[] = {(pCodecCtx->width)*((pCodecCtx->height == 720) ? 720 : 
  
     pCodecCtx->height)*sizeof(uint8_t)*3};
  
     plhs[0] = mxCreateNumericArray(1,dims,mxUINT8_CLASS, mxREAL);
  
      //plhs[0]=mxCreateDoubleMatrix(pCodecCtx->height,pCodecCtx-
  
      >width,mxREAL);
  
     point=mxGetPr(plhs[0]);
  
     memcpy(point, pFrame_BGR24->data[0],(pCodecCtx->width)*(pCodecCtx-
  
      >height)*sizeof(uint8_t)*3);
  
  }

• Concatenate / Join MP4 files using ffmpeg and windows command line batch NOT LINUX

  10 septembre 2022, par julesverne

  I've written a batch script that attempts to take a generic introductory title video (MP4) that runs for 12 seconds and attaches it to the beginning of 4 other MP4 videos (same video but each has a different language audio track)

  



  According to ffmpeg syntax here : http://ffmpeg.org/trac/ffmpeg/wiki/How%20to%20concatenate%20%28join,%20merge%29%20media%20files the concat demuxer needs to be run from a text file that looks like this :

  



  # this is a comment
file '/path/to/file1'
file '/path/to/file2'
file '/path/to/file3'


  



  I believe everything in my script up until the point of joining the files appears to be working correctly. But I get this error :

  



  [concat @ 04177d00] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\frenchfile.mp4'
filelistFrench.txt: Invalid data found when processing input
[concat @ 03b70a80] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\spanishfile.mp4'
filelistSpanish.txt: Invalid data found when processing input
[concat @ 0211b960] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\basquefile.mp4'
filelistBasque.txt: Invalid data found when processing input
[concat @ 03a20a80] Line 2: unknown keyword ''C:\Users\Joe\1May\session3\readyforfinalconversion\Englishfile.mp4'
filelistEnglish.txt: Invalid data found when processing input


  



  I believe the issue lies in the text file I'm creating. Please excuse my n00b ignorance, but sometimes new script makers like myself get confused about developer jargon and may take things literally.

  



  So when I look at that example text file they gave, am I correct in thinking THIS is what my text file should look like ?

  



  # this is a comment
Titlefile.mp4 'C:\Users\Joe\1May\session3\readyforfinalconversion\Titlefile.mp4'
Englishfile.mp4 'C:\Users\Joe\1May\session3\readyforfinalconversion\Englishfile.mp4'


  



  Again, am I being too literal ? are the quotations correct ? Are the slashes correct ? In the example they provide the slashes in the path are / instead of normal windows \ . I'll provide the entire script in case it helps.

  



  @echo off

setlocal EnableDelayedExpansion

rem Create an array of languages
set i=0
for %%a in (French Spanish Basque English) do (
   set /A i+=1
   set term[!i!]=%%a
)

rem Get the title video file name from user

set /p titlevideofilename=What is the title video file 

name?

rem create a path variable for the title video file

set pathtotitlevideo=%~dp0%titlevideofilename%

rem Get the names of the different language video files to append to the title video
rem create a path variable for each different language video files

for /L %%i in (1,1,4) do (
   set /p language[%%i]=what is the name of the !term

[%%i]! file you want to append after the title video?
   set pathtofile[%%i]=%~dp0!language[%%i]!
)

rem create data file for ffmpeg based on variable data

for /L %%i in (1,1,4) do (
    echo # this is a comment>>filelist!term[%

%i]!.txt
    echo file '%pathtotitlevideo%'>>filelist!term[%

%i]!.txt
    echo file '!pathtofile[%%i]!'>>filelist!term[%

%i]!.txt
)

cls

rem join files using ffmpeg concat option

for /L %%i in (1,1,4) do (
   c:\ffmpeg\ffmpeg\bin\ffmpeg.exe -loglevel error -f 

concat -i filelist!term[%%i]!.txt -c copy !language[%

%i]!.!term[%%i]!.withtitle.mp4
)

endlocal

:eof
exit


  



  EDIT
  
Thanks to @foxidrive making me look at the simplicity of it... it occurred to me that Apparently I wasn't being literal enough. I made these 3 changes and script works perfectly now
1 : "file" in there example literally meant the word "file" 
2 : needed the use of single quotes not double quotes as it shows in there example. 
3 : Used "\" instead of "/" as they have in there example.

  



  So NOW my code to create the text files looks like this :

  



  rem create data file for ffmpeg based on variable data

for /L %%i in (1,1,4) do (
    echo # this is a comment>>filelist!term[%

%i]!.txt
    echo file '%pathtotitlevideo%'>>filelist!term[%

%i]!.txt
    echo file '!pathtofile[%%i]!'>>filelist!term[%

%i]!.txt
)


  



  So NOW my text file looks like this :

  



  # this is a comment    
file 'C:\Users\Joe\1May\session3\readyforfinalconversion\Titlefile.mp4'
file 'C:\Users\Joe\1May\session3\readyforfinalconversion\Englishfile.mp4'