python-opencv link error

Hello,
I have an issue with python-opencv (with opencv2.3-7 installed)
when i try to import it in python, i have the following error :

>>> import cv2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: libavcodec.so.52: cannot open shared object file: No such file or directory

the result of ldd show the same problem :
ldd /usr/lib/pyshared/python2.7/cv2.so | grep not
 libavcodec.so.52 => not found
 libavformat.so.52 => not found
 libavutil.so.49 => not found
 libswscale.so.0 => not found

Is it a known issue ?
How i can fix this ?

regards,
Alexandre