Hope you'll have time to check this out.. It's free software (GNU copyright)
Max
http://www.lightlink.com/mhp/lpp
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Digital voice using 4,800 bps modems...
Features:
* Real Time Linear Predictive Coding (LPC) coder
* Compression better than an astounding 97%
* Compress either sound files from disk or real time (from /dev/dsp)
* File player
* Network support allows voice link (half-duplex at present) using
standard slow-speed dial-up modems (4,800 bps or better)
* Multicast daemon (server process) for audio distribution to
several clients simultaneously
Requirements:
* Linux (and other Un*x systems, untested)
* Sound Card and driver supporting /dev/dsp interface
* (Optional) For network support, you need a TCP/IP Net connection
(4,800 bps or better)
Future Possibilities: (This does not represent a commitment)
* Full Duplex voice operation
* Encryption for secure communication support
* Audio Multiplexing
* Integration with the Web via CGI (server) and plug-ins (client)
* Voice Mail
Availability: (Help Wanted: Alpha Testers)
See: http://www.lightlink.com/mhp/lpp
Copyright:
Free Software (GNU Public License)
Includes public domain LPC software developed by the United States
Government
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Further Information
The speech coder uses approx. 25% CPU of a P5-100 for real time
operation. The decoder uses about 12-13%. The encoder can read WAV
format files or for real-time sampling reads /dev/dsp. The decoder can
output audio either to the speakers or to a file. The system uses 16
bit mono data sampled at 8,000 per sec.
There is also a network option allowing the encoder and player to run
on different machines. You can also have multicast servers which use
close to zero CPU time when serving pre-coded files.
Audio Samples
This demo file was captured from one channel of a stereo FM broadcast
and encoded at 8,000 sample/sec, 16 bit. The file starts with the
voice of a male announcer (Daniel Shorr) and ends abruptly during a
weather broadcast by a female announcer. During a portion of the
sample there is some light jazz guitar. The compressed version of this
file is 53,248 bytes!
The sample sound file can be downloaded here:
http://www.lightlink.com/mhp/lpp
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? Copyright, 1996 Max H. Parke