GSM 06.10 Lossy Speech Compressor Library and Utilities
Contains libraries and binaries for a GSM speech compressor. libgsm
contains a standard implementation of the European GSM 06.10
provisional standard for full-rate speech transcoding, prI-ETS 300 036,
which uses RPE/LTP (residual pulse excitation/long term prediction)
coding at 13 kbit/s. GSM 06.10 compresses frames of 160 13-bit samples
(8 kHz sampling rate, which is 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). The interfaces offered are a front-end modeled after compress(1)
and a library API. Compression and decompression run faster than
real-time on most SPARC stations. The implementation has been verified
against the ETSI standard test patterns.