Description:

This is a free and public implementation of GSM audio encoding and
decoding. The gsm library is used in many free software projects
including 'rplay', but has never been packaged as a stand-alone shared
library. GSM encoding has specific uses in transmission of packetized
audio over the Internet.

GSM 06.10 compresses frames of 160 13-bit samples (8 kHz sampling
rate, i.e. a frame rate of 50 Hz) into 260 bits; for compatibility
with typical UNIX applications, our implementation turns frames of 160
16-bit linear samples into 33-byte frames (1650 Bytes/s). The quality
of the algorithm is good enough for reliable speaker recognition; even
music often survives transcoding in recognizable form (given the
bandwidth limitations of 8 kHz sampling rate).