Here are some commands issued on SuSe 8.1 with the final desire to remove libsndfile
(just installed with rpm -i some minutes before):

# rpm -e libsndfile-1.0.0-18.rpm
error: package libsndfile-1.0.0-18.i586.rpm is not installed
# rpm -i libsndfile-1.0.0-18.rpm
package libsndfile-1.0.0-18 is already installed

I got badly confused at this point. Do you have any idea as to whether that package is installed or not?

A related matter: I installed libsndfile previously as tape2mp3 needs it.
However, when compiling tape2mp3 from source, I got an error that there is no 'sfinfo.samples' member.
I suspect that tape2mp3 may have been prepared for an older libsndfile version.
Do you know something about this? Which version does it depend on?

This command will query the RPM database for libsndfile packages.
rpm -qa | grep libsndfile

If the libsndfile package is not found, you may consider trying to force the installation.
However, I never had such a problem before, so this is only a suggestion.

I tend to suggest a rebuild of the database when something odd/conflicing like that occurs. It occasionally helps, and rarely hurts:
rpm --rebuilddb
rpm -qa | grep libsndfile



Cool

Thanks for the tips.
'rpm -qa' helped me to find out that I have to omit the trailing .i386.rpm when uninstalling the rpm.

As for the other issue, I checked the libsnd changelog and it seems that they simply renamed the name sfinfo.samples member (variable) to sfinfo.frame. So, actually, I
- either try to find a newer tape2mp3 developed for the recent version of libsndfile (there is none)
- or find and older libsndfile version (google searched, but the recent version is everywhere)
- or rename the variable in the tape2mp3 source files.
Never did c programming, but I will try the third option.