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• Problem to capture a video in 4K with FFmpeg

  16 mars 2020, par Ale7

  I am a new user of FFmpeg. I am trying to capture a ten minutes video in mp4 format, on 4 4K’s slot and 4 FHD’s slot with cards video Pro Capture by Magewell.
  My machine has the following characteristics :

  • OS : Windows Server 2012
  • RAM : 64 GB
  • CPU : 2 processors Intel Xeon E5-2640 v3 @ 2.60 GHz

  The FFmpeg script, for slot 4K (I change resolution for FHD), used is the following :

  ffmpeg -rtbufsize 2048M -re -y -thread_queue_size 20384 -pix_fmt yuv420p -f dshow -video_size 3840x2160 -r 50 -i video="Video (05-0 Pro Capture HDMI 4K+)"  -codec:v libx264  -preset ultrafast -threads 8 -pix_fmt yuv420p -tune fastdecode -bufsize 2048M output.mp4

  This command is the best solution found at the moment, but the CPU goes up to 100% and the buffer fills up quickly and starts to drop the frames.
  So, my question : Is there a way to improve it or is a limit, principally, of the my machine ?
  If it is a machine limit, you would indicate me the minium requirments to do that.

  Thanks in advance to everyone.

• problem with "subprocess.Popen" AFTER make .exe file

  1er février 2020, par afcc0060

  im try to convert mp3 to mp4 with ffmpeg (command line)
  everything is well and program runs correctly.
  i have one progressbar and handle it from this function by reading ffmpeg command line output

  cls_wnd.pbar_step(line.lower())

  but after make (single) .exe file with pyinstaller program not run and did not convert anything

          def _cli(self ,cls_wnd ,cmd):
  
              errors = False
  
              cmd_output=""
  
  
  
              line=''
  
              try:
  
                      p = subprocess.Popen(cmd ,stdout=subprocess.PIPE ,
  
                                                stderr=subprocess.STDOUT ,
  
                                                universal_newlines=True ,
  
                                                shell=False ,
  
                                                creationflags = subprocess.CREATE_NO_WINDOW)
  
  
  
                      for line in p.stdout:
  
                              if cls_wnd.bt02.cget('text').lower()!="cancel":
  
                                      p.kill()
  
                                      return cmd_output, True ,'cancel'
  
                              cmd_output+=line
  
                              if line.lower().find('duration:')>-1 or line.lower().find('frame=')<1:
  
                                      cls_wnd.pbar_step(line.lower())
  
                              cls_wnd.root.update()
  
  
  
                      stdoutdata, stderrdata = p.communicate()
  
                      if p.wait() != 0:
  
                              p.kill()
  
                              return cmd_output, True ,line
  
                      p.kill()
  
                      return cmd_output, errors ,' '
  
              except OSError as e:
  
                      p.kill()
  
                      return cmd_output,True,' exit from except '
  
              return '',True,'exit from _cli end'

  cmd is somthnig like this

  cmd='ffmpeg -y -loop 1 -i 1.jpg -i 1.mp3 -c:a copy -c:v libx264 -shortest 1.mp4'

  make .exe file with this command

  pyinstaller -w --onefile  mp3tomp4.py --onefile

  if i dont use’-w’ every thing is well .. but that ugly black cmd-windows shown and i can not close or hide it

• Problem while building libffmpeg.so from ffmpeg sources (undefined symbol : avcodec_version)

  10 octobre 2023, par serggt1

  I'm trying to build libffmpeg.so shared library from sources on Linux. Sources are here FFmpeg.git.

  


  I run

  


  ./configure
make -j4

gcc -shared \
    libavcodec/libavcodec.a \
    libavdevice/libavdevice.a \
    libavfilter/libavfilter.a \
    libavformat/libavformat.a \
    libavutil/libavutil.a \
    libswresample/libswresample.a \
    libswscale/libswscale.a \
    -o libffmpeg.so


  


  The problem is the resulting libffmpeg.so is only 15 KB and says

  


  dlsym fail : /opt/yandex/browser/libffmpeg.so: undefined symbol: avcodec_version


  


  What do I wrong and how to link the library in correct way ?

  


  UPD :

  


  Now trying with this :

  


  ./configure --enable-pic --disable-programs  --enable-gpl --enable-version3 --enable-nonfree

make -j4

ld \
    -rpath-link=/usr/lib \
    -L/usr/lib \
    -L/lib \
    --library=c --library=m --library=z --library=dl --library=log \
    -soname libffmpeg.so -shared -nostdlib -Bsymbolic --whole-archive --no-undefined \
    libavcodec/libavcodec.a \
    libavdevice/libavdevice.a \
    libavfilter/libavfilter.a \
    libavformat/libavformat.a \
    libavutil/libavutil.a \
    libswresample/libswresample.a \
    libswscale/libswscale.a \
    -o libffmpeg.so


  


  Error is ld: cannot find -lc: No such file or directory