Latest OpenMPT versions support mp3 samples, but I can't load them in sample editor, they sound like noise. Have lame_enc.dll in OpenMPT folder.
OpenMPT does not support mp3 samples. lame.enc is only for encoding songs in mp3 format instead of exporting in wav-format.
In fact, the latest test versions support loading of MPEG (MP1/MP2/MP3) files, but as the manual says (http://wiki.openmpt.org/Manual:_Samples#File_Toolbar), you need libmpg123-0.dll (http://www.mpg123.de/download/win32/?C=M;O=D) to be able to use that feature. This file won't be included with OpenMPT for now because of all the patent trouble. I don't know if I could include it without having to pay any royalties.
Thanks :)