libav_or_ffmpeg.sh

libav_or_ffmpeg()
{
  compile_check_libav_or_ffmpeg()
  {
    _CFLAGS=$(pkg-config --cflags libavcodec)
    CC=cc

    ${CC} -x c $_CFLAGS - -o /dev/null <<- EOF
    #include <libavcodec/avcodec.h>
    #include <libswscale/swscale.h>

    int main()
    {
      #if LIBAVCODEC_VERSION_MICRO >= 100
      #error ffmpeg
      #elif LIBAVCODEC_VERSION_INT < AV_VERSION_INT(53, 47, 100)
      (void)CODEC_ID_G2M; /* not declared, it is libav */
      #error ffmpeg
      #else
      #error libav
      #endif
    }
EOF
  }
  cc_output=$(compile_check_libav_or_ffmpeg 2>&1)

  if [ "$(echo "$cc_output" | grep "error: libavcodec/avcodec.h")" ]; then
    exit 1 # libavcodec header file not found
  elif [ "$(echo "$cc_output" | grep "CODEC_ID_G2M")" ]; then
    echo libav
  else
    #echo "$cc_output"
    echo "$cc_output" | grep -o "ffmpeg\|libav"
  fi
}

libav_or_ffmpeg