This library is a thin wrapper for [libsoxr](https://sourceforge.net/projects/soxr/) which is a "High quality, one-dimensional sample-rate conversion library".
This wrapper library is licensed the same as libsoxr itself: LGPLv2.
For direct access to the native libsoxr functions, you can use the [libsoxr-sys](https://github.com/lrbalt/libsoxr-sys) crate. The documentation including examples can be found [here](https://lrbalt.github.io/libsoxr-rs/libsoxr/).