title: Can not install opencv using brew or make on mac osx
body: <p>I'm trying to install opencv by brew ,</p>
  
  <p>but showed me the following errors.</p>
  
  <p>I knew i should tap "brew tap homebrew/homebrew-science"</p>
  
  <p>but it didn't work.</p>
  
  <p>is there any idea , or should i show what information by what command to fix the problem quickly.</p>
  
  <p>thanks~</p>
  
  <pre><code>[local] $ brew update
  Error: Permission denied - /var/folders/wt/ffjhmkgx4292wtm22b966mdc0000gn/T/.gitignore20130904-819-fdlv65-0 or /usr/local/Library/Formula/.gitignore
  [local] $ sudo brew update
  Already up-to-date.
  [local] $ sudo brew install opencv
  Warning: It appears you have MacPorts or Fink installed.
  Software installed with other package managers causes known problems for
  Homebrew. If a formula fails to build, uninstall MacPorts/Fink and try again.
  Error: No available formula for opencv
  [local] $ brew tap homebrew/homebrew-science
  Error: Already tapped!
  [local] $ sudo brew tap homebrew/homebrew-science
  Error: Already tapped!
  [local] $ sudo brew install opencv
  Warning: It appears you have MacPorts or Fink installed.
  Software installed with other package managers causes known problems for
  Homebrew. If a formula fails to build, uninstall MacPorts/Fink and try again.
  Error: No available formula for opencv
  [local] $ brew install opencv
  Warning: It appears you have MacPorts or Fink installed.
  Software installed with other package managers causes known problems for
  Homebrew. If a formula fails to build, uninstall MacPorts/Fink and try again.
  Error: No available formula for opencv
  </code></pre>
  
  <p>if I tried to make manually by the tutorial <a href="http://tilomitra.com/opencv-on-mac-osx/" rel="nofollow">http://tilomitra.com/opencv-on-mac-osx/</a>
  I will see the error after make -j8</p>
  
  <pre><code>     _ff_xvid_rate_control_uninit in libavcodec.a(libxvid_rc.o)
    "_xvid_plugin_lumimasking", referenced from:
        _xvid_encode_init in libavcodec.a(libxvid.o)
    "_xvid_plugin_single", referenced from:
        _xvid_encode_init in libavcodec.a(libxvid.o)
  ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  make[2]: *** [lib/libopencv_highgui.2.4.6.dylib] Error 1
  make[1]: *** [modules/highgui/CMakeFiles/opencv_highgui.dir/all] Error 2
  make: *** [all] Error 2
  </code></pre>