anchor.diff:      #srt
       tesseract
       v4l_lib
  +    #vapoursynth
       vid-stab
       wavpack
       x264
  
positive.code: #, twolame
  #, utvideo
  , v4l_lib
  , vid-stab
  #, vo-aacenc
  , vo-amrwbenc ? null
  
negative.code:     };
      "9.9" = {  # Git
        fetchzipversion = 6;
        version = "2018.05.10";
        rev = "974eb4aaaa7d96a996c61030fca4095c3c2c6284";
        sha256 = "a91659bba6197e0f44768965b9afa240c33bffc85c2c1a38e15597799d0c3b81";
      };
    };
    source = sources."${channel}";
  