Problem

You cannot play new WMA media (aka wma9) content on your 64bit Linux system because of missing audio format support, e.g you get an error message similar like that:

Cannot find codec for audio format 0x162.

Solution

Get win32codecs

Unpack the files to /usr/lib/codecs ,e.g. with

    tar xvjf essential-20071007.tar.bz2
    mkdir -p /usr/lib/codecs
    mv essential-20071007/* /usr/lib/codecs/
    ln -s /usr/lib/codecs /usr/lib/win32 

add the path to the library search path so the libraries can be found:

    echo "/usr/lib/win32/" > /etc/ld.so.conf.d/win32codecs.conf
    ldconfig 

Obtain the mplayer 32bit package (built for Ubuntu 9.10 Karmic Koala). Only the 32bit version can make use of the win32codecs!

Install the deb package:

    dpkg -i mplayer32_1.0svn_amd64.deb 

Run the 32bit mplayer with /usr/bin/mplayer32 <URL>

MPlayer should now play the stream or file, enjoy!!