ref: 4de92cb7833368d1c460db52ba5b0c7f179f3d52
dir: /COPYING/
SoX source code is distributed under two main licenses. The two licenses are in the files LICENSE.GPL and LICENSE.LGPL. sox.c, and thus SoX-the user application, is distributed under the GPL, while the files that make up libsox are licensed under the less restrictive LGPL. Note that some of the external packages that can be linked in to libsox are GPLed and/or may have licensing problems, so they can be disabled at configure time with the relevant--with-* options. If libsox is built with such libraries, it must be distributed under the GPL.