anchor.diff:      /*
        *  Hardware accelerators
        */
  -    (fflag "--disable-amf" "3.5")  # macOS
  +    (fflag "--disable-amf" "3.5")
       "--disable-audiotoolbox"  # macOS
       "--${boolEn (
         nvidia-cuda-toolkit != null
  
positive.code:     #"--${boolEn (twolame != null)}-libtwolame"
      /**/"--disable-libtwolame"
      "--${boolEn (v4l_lib != null)}-libv4l2"
      "--${boolEn (v4l_lib != null)}-v4l2_m2m"
      "--${boolEn (vid-stab != null)}-libvidstab"
      /**/"--disable-libvmaf"
      "--${boolEn (vo-amrwbenc != null)}-libvo-amrwbenc"
  
negative.code:       sha256 = "5a77278a63741efa74e26bf197b9bb09ac6381b9757391b922407210f0f991c0";
      };
      "9.9" = { # Git
        version = "2017.12.15";
        rev = "3c6dc270355f27645cf931fae1ed2dc1405507f8";
        sha256 = "64f9b15adaf585ddca918db9bb6e202ccc795c56579ce70b2f9fe075d5c043fa";
      };
    };
    source = sources."${channel}";
  