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• "ERROR : libopencv not found" when compiling ffmpeg

  13 avril 2023, par ArnoBen

  I am trying to install ffmpeg with the libopencv libraries and it fails with the error "ERROR : libopencv not found".

  


  I did install libopencv with sudo apt install libopencv-dev which now prints libopencv-dev is already the newest version (3.2.0+dfsg-4ubuntu0.1), and I can see the files in /usr/include/opencv2.

  


  Here is my full script to compile ffmpeg :

  


  cd ~/ffmpeg_sources && \
wget -O ffmpeg-snapshot.tar.bz2 https://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" \
  --extra-libs="-lpthread -lm" \
  --ld="g++" \
  --bindir="$HOME/bin" \
  --enable-gpl \
  --enable-gnutls \
  --enable-libopencv \
  --enable-libtensorflow \
  --enable-libx264 \
  --enable-libfdk-aac \
  --enable-nonfree && \
PATH="$HOME/bin:$PATH" make -j4 && \
make -j4 install && \
hash -r


  


  It works fine if I remove the --enable-libopencv line.

  


  I'm running Ubuntu 18.04.6.

  


  Any help would be appreciated.

  


• Error "option not found" when trying to output a video file through decklink as PAL standard

  11 avril 2023, par seriously

  I have an ffmpeg build compiled with decklink which is running fine. What I want to achieve is to output a certain video file through the black magic decklinks sdi output port. To do so I used the command ffmpeg -standard PAL -i myvideo.mp4 -pix_fmt uyvy422 -s 1920x1980 -r 25000/1000 -f decklink "DeckLink SDI 4K" but I get error unrecognized option 'standard'. What am I doing wrong or want is the proper way to set PAL as the standard ? Thanks in advance.

  


  super user post suggesting to use -standard as a valid option : https://superuser.com/questions/885880/configure-ffmpeg-and-ffplay-to-pal-signal

  


• "No Output pad"error when using ffmpeg to create a subtitle overlay

  7 avril 2023, par user3324136

  I am using a Lambda function to run ffmpeg to rescale a video and then add subtitles from an .ass file.

  


  I have tried a few variations, but am continuing to get an error :
[AVFilterGraph @ 0x721bec0] No output pad can be associated to link label '2'.

  


  The code is below, with the error stemming from the line :
'[0]scale=iw/1.5:ih/1.5,setsar=1[v];[1][v]overlay=-100:320[vid][2]overlay[out]'

  


  CODE

  


      try:
        subprocess.check_call([
            '/opt/ffmpeg',
            '-i', source_file,
            '-i', padding_image_file,
            '-i', subtitles_file,    # Input caption file path
            '-filter_complex',
            '[0]scale=iw/1.5:ih/1.5,setsar=1[v];[1][v]overlay=-100:320[vid][2]overlay[out]',
            '-c:a', 'copy', '-crf', '20', '-preset', 'fast', '-movflags', '+faststart',
            '-y', output_file
    ])