anchor.diff:      (enableFeature swscaleAlphaBuild "swscale-alpha")
       (enableFeature hardcodedTablesBuild "hardcoded-tables")
       (enableFeature safeBitstreamReaderBuild "safe-bitstream-reader")
  -    (enableFeature memalignHackBuild "memalign-hack")
       (if multithreadBuild then (
          if isCygwin then
            "--disable-pthreads --enable-w32threads"
  
positive.code: , swscaleAlphaBuild ? true # Alpha channel support in swscale
  , hardcodedTablesBuild ? true # Hardcode decode tables instead of runtime generation
  , safeBitstreamReaderBuild ? true # Buffer boundary checking in bitreaders
  , memalignHackBuild ? false # Emulate memalign
  , multithreadBuild ? true # Multithreading via pthreads/win32 threads
  , networkBuild ? true # Network support
  , pixelutilsBuild ? true # Pixel utils in libavutil
  
negative.code: #, vo-aacenc ? null # AAC encoder
  #, vo-amrwbenc ? null # AMR-WB encoder
  , wavpack ? null # Wavpack encoder
  , x264 ? null # H.264/AVC encoder
  , x265 ? null # H.265/HEVC encoder
  , xavs ? null # AVS encoder
  