ffmpeg installation

if you get error below while running "ffmpeg" command,

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error while loading shared libraries: libavdevice.so.52: cannot open shared object file: No such file or directory

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This error usually comes when ldconfig does not know where to search for the libraries.
In redhat/fedora/centos systems, i did the following:

vi /etc/ld.so.conf

inside, put :
/usr/local/lib
save,
then do

ldconfig