configure script needs to have a --disable-twolame (same as --disable-lame) flag in case you don't want to have twolame support. This is a prerequisite for distribution that don't package twolame due to patent infringement issues.
Can you point me to a single mp2 patent that hasn't yet expired in any particular country?
Good question. It seems that there is an ongoing discussion on the community about twolame, since it's not clear if it infringes patents. It doesn't include code for mp3, so it's safe in this area, but it seems to include code from MPEG-1 implementations which may violate some patents.
Currently some major distributions choose not to include it on main/official repos. For instance Ubuntu has it on universe and thus idjc is on multiverse, which is a repo for non-free software. On Fedora twolame is on 3rdparty rpmfusion repo. I maintain idjc, but if it depends on twolame i'll have to remove it from the main repo, which will be bad because then it should also been removed from the Audio Spin.
I'll have a quick question on legal team to see what's the current state of twolame and I'll be back :)
Nevertheless, it would be generally good idea to have such a disable switch in the same sense that you provide a way to disable speex or flac support.
Also I can't find a disable flag for mpg123 support, which certainly has patent issues.
Git master now has --disable-twolame.
I pushed a stealth update to the sourceforge file release system. Hopefully it will mirror and RSS but if it doesn't you can still get the latest IDJC source from the git repository. The commit is tagged 0.8.8-extra-build-options.
The following is now possible.
,/configure --disable-mpg123 --disable-lame --disable-twolame
Both mpg123 and libmp3lame will run-time link if the libraries are installed.