| PackageDescription | Shared libraries for GSM speech compressor
This package contains runtime shared libraries for libgsm, an
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.
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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).
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The interfaces offered are a front end modelled after compress(1), and
a library API. Compression and decompression run faster than realtime
on most SPARCstations. The implementation has been verified against the
ETSI standard test patterns. |