tools for losslessly manipulating mp3s

[nia <nia%NetBSD.org@localhost>]

yo pkgsrc-users@,

for Legacy Reasons, I have a significant collection music that
is only available in MP3 and is no longer available for purchase
(etc.). Some of this music was clearly recorded from vinyl and
other sources without properly removing the last part of the
previous track.

I wonder if there's any software in pkgsrc (or that I could package)
which can cut MP3s without re-encoding them or causing any loss in
quality.