anchor.diff:      (enableFeature gprofSupport "gprof")
       (enableFeature gcovSupport "gcov")
       # Required to build shared libraries
  -    (enableFeature (!isCygwin) "pic")
  +    (enableFeature true "pic")
       (enableFeature (isi686 || isx86_64) "use-x86inc")
       (enableFeature optimizationsSupport "optimizations")
       (enableFeature runtimeCpuDetectSupport "runtime-cpu-detect")
  
positive.code:   buildInputs = [ ]
      ++ optionals unitTestsSupport [ coreutils curl ];
  
    enableParallelBuilding = true;
  
    crossAttrs = let
      isCygwin = stdenv.cross.libc == "msvcrt";
      isDarwin = stdenv.cross.libc == "libSystem";
    in {
      dontSetConfigureCross = true;
      configureFlags = configureFlags ++ [
        #"--extra-cflags="
        #"--prefix="
        #"--libc="
        #"--libdir="
        "--enable-external-build"
        # libvpx darwin targets include darwin version (ie. ARCH-darwinXX-gcc, XX being the darwin version)
        # See all_platforms: https://github.com/webmproject/libvpx/blob/master/configure
        # Darwin versions: 10.4=8, 10.5=9, 10.6=10, 10.7=11, 10.8=12, 10.9=13, 10.10=14
        "--force-target=${stdenv.cross.config}${(
                if isDarwin then (
                  if      stdenv.cross.osxMinVersion == "10.10" then "14"
                  else if stdenv.cross.osxMinVersion == "10.9"  then "13"
                  else if stdenv.cross.osxMinVersion == "10.8"  then "12"
                  else if stdenv.cross.osxMinVersion == "10.7"  then "11"
                  else if stdenv.cross.osxMinVersion == "10.6"  then "10"
                  else if stdenv.cross.osxMinVersion == "10.5"  then "9"
                  else "8")
                else "")}-gcc"
        (if isCygwin then "--enable-static-msvcrt" else "")
      ];
    };
  
    meta = with stdenv.lib; {
      description = "WebM VP8/VP9 codec SDK";
      homepage    = http://www.webmproject.org/;
  
negative.code:     (enableFeature ontheflyBitpackingSupport "onthefly-bitpacking")
      (enableFeature errorConcealmentSupport "error-concealment")
      # Shared libraries are only supported on ELF platforms
      "--disable-static --enable-shared"
      (enableFeature smallSupport "small")
      (enableFeature postprocVisualizerSupport "postproc-visualizer")
      (enableFeature unitTestsSupport "unit-tests")
  