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• Unable to link against FFmpeg libaries

  28 octobre 2015, par Cody

  I tried to build this, but always got link-time error.

  #include <libavutil></libavutil>log.h>    
  
  int main(int argc, char *argv[])
  
  {
  
      ::av_log_set_flags(AV_LOG_SKIP_REPEATED);
  
      return 0;
  
  }

  My distro is Debian GNU/Linux 8 (jessie). The FFmpeg was built by myself, and the configure command was...

  $ ./configure --prefix=/usr/local --disable-static --enable-shared \
  
  > --extra-ldflags='-Wl,-rpath=/usr/local/lib'

  The link-error is as follows.

  $ g++ foo.cpp -D__STDC_CONSTANT_MACROS -Wall \
  
  > -Wl,-rpath=/usr/local/lib \
  
  > $(pkg-config --cflags --libs libavutil)
  
  /tmp/ccKzgEFb.o: In function `main':
  
  foo.cpp:(.text+0x17): undefined reference to `av_log_set_flags(int)'
  
  collect2: error: ld returned 1 exit status

  where the output of pkg-config is...

  $ pkg-config --cflags --libs libavutil
  
  -I/usr/local/include -L/usr/local/lib -lavutil

  The objdump shows that the shared object libavutil.so does have av_log_set_flogs inside.

  $ objdump --dynamic-syms /usr/local/lib/libavutil.so | grep 'av_log_set_flags'
  
  000260f0 g    DF .text  0000000a  LIBAVUTIL_54 av_log_set_flags

  Please note that the g++ command used to build the above application had a linker option -Wl,-rpath=/usr/local/lib, though it still doesn’t work. Also, I’ve tried to monitor with inotifywait if the other version provided by the distro were called. They were not, and the one being opened during execution of g++ was /usr/local/lib/libavutil.so.

  Summary :

  1. /usr/local/lib/libavutil.so does have the symbol.

  2. -rpath was used to force to link against the shared library.

  3. Why link-time error ? T_T

  Any suggestion or information would be highly appreciated ! Thanks !

  REEDIT : ffplay works fine and ldd shows it use /usr/local/lib/libavutil.so. So, the libraries seems not broken, and the problem becomes how to build my own codes to use the libraries.

• Could NOT find FFmpeg (missing : swresample) (found version "56.1.0")

  28 juin 2016, par sushi

  I try to install obs (Open Broadcaster Software) in my Kali Linux 2.

  I follow this instruction. I have no problem until the obs building :

  cmake -DUNIX_STRUCTURE=1 -DCMAKE_INSTALL_PREFIX=/usr ..

  Where I get this error :

  Could NOT find FFmpeg (missing: swresample) (found version "56.1.0")

  I found this topic but I can’t use this command :

  apt-get -t jessie-backports install libswresample-dev

  Because I am on Kali Linux.

  This is the output of ffmpeg command :

  ffmpeg version N-79093-g7916f04 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 4.9.2 (Debian 4.9.2-10)
  
    configuration: --prefix=/root/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
  
    libavutil      55. 19.100 / 55. 19.100
  
    libavcodec     57. 28.103 / 57. 28.103
  
    libavformat    57. 28.102 / 57. 28.102
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 39.102 /  6. 39.102
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Hyper fast Audio and Video encoder
  
  usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...
  
  
  
  Use -h to get full help or, even better, run 'man ffmpeg'

• Sending an mp4 video over the network with avconv command to a raspberry pi in a piwall videowall

  21 juillet 2017, par noswoscar

  I would like to send an mp4 video from a raspbery pi to another raspberry-pi (in order to build a piwall) but the command I am using for sending a video stream (tested with correct outcome on other devices) doesn’t work.

  Details :
  I am using the avconv command from libav.org to send an mp4 video from a "master raspberry pi" through the network to my "slave raspberry pi". The raspberry pi (which is receiving the video) has the Raspbian Jessie Operating System on it. The goal of my experiment is to use the pwomxplayer command to display the video received on the "slave raspberry pi".

  The full command i am using for sending the mp4 video stream is as follows :
  avconv -re -i input.mp4 -vcodec libx264 -f h264 -an udp ://224.0.0.1:1234
  (works when sending to my raspberry pi from my dell laptop)

  It is interesting to note that when using the pre-mentioned avconv command on my dell laptop which has an intel processor and debian OS installed, the video stream is sent properly. However, the same command doesn’t work when sending the video stream from a raspberry pi which has an arm processor and raspbian OS installed.
  I wonder why this is !

  Am I right in thinking the arm processor is not interpreting my command avconv as well as the intel processor ? Or is it more a question of architecture ? Or is my avconv command syntax incorrect ?

  Thank you for your help !

  More info :
  Ip address of master raspberry pi : 192.168.72.10
  Ip address of slave raspberry pi : 192.168.72.11
  I am using the route add -net 224.0.0.0 netmask 224.0.0.0 eth0 command on master pi to send the video stream to all laptops connected to my ethernet port.
  The following command works for files ending in .h264 :
  avconv -re -i input.h264 -vcodec libx264 -f h264 -an udp ://224.0.0.1:1234
  (but I would like to send .mp4 files encoded with h264 not just .h264 files)