Trivial wav file resampler using libspeexdsp and libsndfile. For more info on the speex resampler, see the source code.
on macOS:
brew install libsndfile speexdsp
make
or any other platform with pkg-config.
./speexresample infile.wav outfile.wav <output-samplerate> <quality>
quality: 0-10, where 0 is worst, 10 is best