Libsamplerate

Audacity contains code to use Libsamplerate for resampling, but this is not enabled by default due to licensing issues. Instead, Audacity releases use a library called libresample, based on Julius Orion Smith's Resample algorithm.

Libsamplerate can be used if you compile Audacity from source code at the command line, and configure --with-libsampletate. On Windows building with Visual Studio, you can #define USE_LIBSAMPLERATE in win/configwin.h. See Developing On Windows for details.

If you use libsamplerate, you should not install extra plug-ins in Audacity unless they are licensed under the GPL or some licence compatible with it.