anchor.diff:  , avdeviceLibrary ? true
   , avfilterLibrary ? true
   , avformatLibrary ? true
  -, avresampleLibrary ? false  # Libav api compatibility library
   , avutilLibrary ? true
   , postprocLibrary ? true
   , swresampleLibrary ? true
  
positive.code:     };
      "9.9" = { # Git
        fetchzipversion = 5;
        version = "2017.12.15";
        rev = "3c6dc270355f27645cf931fae1ed2dc1405507f8";
        sha256 = "7583460004a078dfe8e3590f4e50be250640c6ef31738516cf67a5db23454c41";
      };
    };
    source = sources."${channel}";
  
negative.code:     "--${boolEn avdeviceLibrary}-avdevice"
      "--${boolEn avfilterLibrary}-avfilter"
      "--${boolEn avformatLibrary}-avformat"
      "--disable-avresample"
      "--${boolEn avutilLibrary}-avutil"
      "--${boolEn (postprocLibrary && gplLicensing)}-postproc"
      "--${boolEn swresampleLibrary}-swresample"
  