Alsa should be installed by default. When you say you installed ‘alsa’ that worries me, because alsa was already installed by default, and you likely installed something else.
To see what alsa apps you have installed, you can type:
rpm -qa '*alsa*'
for example on my PC, I have:
oldcpu@hal2009:~> rpm -qa '*alsa*'
alsa-oss-1.0.17-25.2.x86_64
alsa-utils-1.0.21-3.1.x86_64
alsa-plugins-1.0.21-3.3.x86_64
alsa-oss-32bit-1.0.17-25.2.x86_64
alsa-plugins-32bit-1.0.21-3.3.x86_64
alsa-devel-1.0.21-3.2.x86_64
alsa-docs-1.0.21-3.2.noarch
alsa-1.0.21-3.2.x86_64
Reference amarok, it is one of the applications that is impacted by you getting your openSUSE Linux either for free, or for a very inexpensive price as a boxed set. Novell/SuSE-GmbH do NOT pay to licence the mp3 and other codecs, and hence they are NOT allowed to include the mp3 codec, nor to facilitate its install too much, as they could be sued.
However it is possible to setup amarok to play sound, … many of us do this, and once you know how it takes seconds. … BUT it does take new users a while to figure it out. Its likely that very difficulty, which provides Novell protection against a law suit.
If using openSUSE-11.2 KDE, Amaork will use the sound engine that is setup for the KDE desktop. Many of us use the xine sound engine for our desktop and hence Amarok will use the xine sound engine. But the xine package provided by Novell is crippled for mp3 for the contractual reasons mentioned.
What many of us like to do, is replace the crippled Novell/SuSE-GmbH package “libxine1” with the Packman packaged application “libxine1” (ie same name but the packman version has a “pm” in the version number). Also install packman packaged versions of xine-ui (a user interface) , xine-codecs (extra codecs) and phonon-backend-xine (so to interface xine to your KDE phonon desktop). Once that is done, go to KDE > Configure Desktop > Multimedia > Backed and select “xine”.
Also look at YaST > Hardware > Sound, and note the order of sound devices, and ensure you have a similar order (for the 1st device) in KDE > Configure Desktop > Multimedia .
Your amarok should then work.
Reference installing applications from Packman, note Packman packaged apps don’t work well with videolan packaged apps (because the packagers from each will package the codecs in different locations). Hence IMHO it behooves you to ensure the videolan repository is not added to your repository list of your software package manager, and that Packman is added to your software package manager repository list.
I recommend you limit your nominally enabled list of repositories to ONLY OSS, Non-OSS, Update (which are “official repositories”) and Packman. Only those 4. No others. None. Adding others can cause problems. If you MUST add an application not on those 4 repositories, then add the 5th repository, install the application, and remove the 5th repository. There is guidance HERE for adding repositories: Repositories/11.2 - openSUSE-Community Again, ONLY OSS, Non-OSS, Update and Packman.
You can then install software via YaST > Software > Software Management (and do searches for software there) or you can install software via zypper.
Note, I recommend you do NOT use the 1-click-install and if you decide to use it anyway, ensure you do NOT keep the repositories after a 1 click install is complete.
Now if after the above, you still can’t play MP3, then run xine, select “master of the known universe” under its preferences/settings (a hokey name) and you can tune the output audio mode until you get its sound working. Hopefully this last bit won’t be necessary.