option('fft', type: 'combo', choices: ['auto', 'builtin', 'kissfft', 'fftw', 'vdsp', 'ipp'], value: 'auto', description: 'FFT library to use. The default (auto) will use vDSP if available, the builtin implementation otherwise.') option('resampler', type: 'combo', choices: ['auto', 'builtin', 'libsamplerate', 'speex', 'libspeexdsp', 'ipp'], value: 'auto', description: 'Resampler library to use. The default (auto) simply uses the builtin implementation.') option('ipp_path', type: 'string', value: '', description: 'Path to Intel IPP libraries, if selected for any of the other options.') option('extra_include_dirs', type: 'array', value: [], description: 'Additional local header directories to search for dependencies.') option('extra_lib_dirs', type: 'array', value: [], description: 'Additional local library directories to search for dependencies.')