Instal openCV on mac os x 10.6.7 with Xcode

I am trying to install OpenCV on my Mac (OS X v10.6.3) with this guide : http://www.randomsequence.com/articles/opencv-snow-leopard/

The build failed. This'is the error:

ld: library not found for -lavcodec

collect2: ld returned 1 exit status

Command /Developer/开发者_运维技巧usr/bin/g++-4.2 failed with exit code 1

Where can I found and install this library?

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If you followed the article you have macports installed.

If so use it to install openCV e.g.

sudo port install opencv

the current macports installs openCV 2.2.0

If you have not used macports for some time you should update it first to get the latest versions see guide

sudo port selfupdate
sudo port upgrade outdated