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• Slideshow with ffmpeg

  15 août 2017, par Luca

  I want to make a video from many images. I tried using the concat demuxer as explained here but :

  1) I don’t know what the -vsync vfr parameter do and how to use it.

  2) Using the input.txt file I tell explicitly the duration of each image of the slideshow so I guess the input framerate (-framerate) is useless. Can I set the output framerate however with the -r or the -vf fps parameter ?

  3) The images are both .jpg and .png with different resolutions, dimensions etc... Do ffmpeg and the concat demuxer handle this ? Should I optimize something ?

• Compile FFmpeg with libfdk_aac

  18 février 2017, par Toydor

  I been reading on how to convert mp3 to m4a, and found that I must compile FFmpeg if I’ll use the AAC encoder, libfdk_aac.

  But reading FFmpeg guide on how to compile FFmpeg with libfdk_aac makes no sense for a beginner like me.

  To use libfdk_aac the encoding guide says :

  Requires ffmpeg to be configured with —enable-libfdk_aac
  —enable-nonfree.

  Where do I put those flags ?

  Do I put it here somewhere ? :

  cd ~/ffmpeg_sources
  
  git clone --depth 1 git://github.com/mstorsjo/fdk-aac.git
  
  cd fdk-aac
  
  autoreconf -fiv
  
  ./configure --prefix="$HOME/ffmpeg_build" --disable-shared
  
  make
  
  make install
  
  make distclean

  Or maybe here somewhere ?

  cd ~/ffmpeg_sources
  
  git clone --depth 1 git://source.ffmpeg.org/ffmpeg
  
  cd ffmpeg
  
  PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig"
  
  export PKG_CONFIG_PATH
  
  ./configure --prefix="$HOME/ffmpeg_build" \
  
    --extra-cflags="-I$HOME/ffmpeg_build/include" --extra-ldflags="-L$HOME/ffmpeg_build/lib" \
  
    --bindir="$HOME/bin" --extra-libs="-ldl" --enable-gpl --enable-libass --enable-libfdk-aac \
  
    --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx \
  
    --enable-libx264 --enable-nonfree --enable-x11grab
  
  make
  
  make install
  
  make distclean
  
  hash -r

  If I’m reading the compile guide right I guess that these two chunks of code is what I need to compile FFmpeg.

  I’m using Ubuntu server 12.4

  UPDATE

  After upgrading my system to Ubuntu 16.04 I had to install ffmpeg again.
  I still needed libfdk-aac. Fortunately there’s a good step-by-step guide at http://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu on how to compile ffmpeg.

  I thought I would share how to compile if just interested in compiling ffmpeg with libfdk-aac and libmp3lame.

  If you haven’t already a bin in home directory :

  mkdir ~/bin 

  Install dependencies. Didn’t need the non-server packages :

  sudo apt-get update
  
  sudo apt-get -y install autoconf automake build-essential libass-dev libfreetype6-dev libtheora-dev libtool libvorbis-dev pkg-config texinfo zlib1g-dev 

  Then install the encoders. Had to install yasm as well, otherwise I got errors when compiling.

  sudo apt-get install libfdk-aac-dev
  
  sudo apt-get install libmp3lame-dev
  
  sudo apt-get install yasm

  Then compile ffmpeg with needed flags

  cd ~/ffmpeg_sources
  
  wget http://ffmpeg.org/releases/ffmpeg-snapshot.tar.bz2
  
  tar xjvf ffmpeg-snapshot.tar.bz2
  
  cd ffmpeg
  
  PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure \
  
  --prefix="$HOME/ffmpeg_build" \
  
  --pkg-config-flags="--static" \
  
  --extra-cflags="-I$HOME/ffmpeg_build/include" \
  
  --extra-ldflags="-L$HOME/ffmpeg_build/lib" \
  
  --bindir="$HOME/bin" \
  
  --enable-libass \
  
  --enable-libfdk-aac \
  
  --enable-libfreetype \
  
  --enable-libtheora \
  
  --enable-libvorbis \
  
  --enable-libmp3lame \
  
  --enable-nonfree \
  
  --enable-gpl
  
  PATH="$HOME/bin:$PATH" make
  
  make install
  
  make distclean
  
  hash -r

• what is a good way to calculate frame rate using of a video ffmpeg ?

  20 septembre 2013, par user1914692

  I find three possible ways :

  (Option 1)
  inVStruct.inVideoStream->r_frame_rate

  [comment :] correct for some videos. Not always correct.
  it is libavformats guess, not exact. (see http://ffmpeg.org/pipermail/ffmpeg-devel/2005-May/003079.html )

  (Option 2)
  (double) inVStruct.inVideoStream->r_frame_rate.num / (double) inVStruct.inVideoStream->r_frame_rate.den

  [comment :] correct for some videos. Not always correct.

  (Option 3)
  (double) inVStruct.inCodecContext->time_base.den / (double) inVStruct.inCodecContext->time_base.num / inVStruct.inCodecContext->ticks_per_frame) ;

  [comment :] correct for some videos. Not always correct.

  Please recommend one for all video files.