config FREETZ_LIB_libspandsp bool "libspandsp (libspandsp.so)" default n select FREETZ_LIB_libm select FREETZ_LIB_libtiff help SpanDSP is a library of DSP functions for telephony, in the 8000 sample per second world of E1s, T1s, and higher order PCM channels. It contains low level functions, such as basic filters. It also contains higher level functions, such as cadenced supervisory tone detection, and a complete software FAX machine.