From: loki@nately.UCSD.EDU (Lance Cottrell)
Date: Fri, 10 Dec 93 15:09:37 PST
To: cypherpunks@toad.com
Subject: Re:  LPC for speech (fwd)
Message-ID: <9312102307.AA27130@nately.UCSD.EDU>
MIME-Version: 1.0
Content-Type: text/plain


:Forwarded message:
:>From jp12745@coewl.cen.uiuc.edu Fri Dec 10 14:46:07 1993
:From: Jeffrey Wayne Porter <jp12745@coewl.cen.uiuc.edu>
:Message-Id: <199312102045.AA16812@eehpx21.cen.uiuc.edu>
:Subject: LPC for speech
:To: jerry@terminus.dell.com (Jeremy Porter)
:Date: Fri, 10 Dec 1993 14:45:49 -0600 (CST)
:X-Mailer: ELM [version 2.4 PL22]
:Content-Type: text
:Content-Length: 948       
:
:Did you know that using LPC (linear predictive coding) on speech can
:near-telephone quality at only 8 k BITs/second?  With a signficant
:decrease in quality (but still very understandable... probably better
:than radio) you can get the rate down to 2kbps.  If you don't mind
:sounding like a speak&spell, you can go to 600bps or less.
:
:
:Using LPC, you could send real-time voice over the
:internet.  It would even work (maybe just barely) over a SLIP
:connection.  According to my professor, LPC can be implemented
:in a simple DSP chip, so I figure a 486 ought to be able to
:handle it, too.  Sound like an interesting (granted maybe not
:too useful) project?  It would be a way of providing secure
:voice communications -- LPC code the speech, encrypt the data
:stream, transmit via v.32bis modem, etc.
:-- 
:--------------------------------------------------------------------
:Jeff Porter
:jporter@uiuc.edu    TA: ECE 290..."ph Jeff Porter" for office hours
:
:
:-- 
:Jeremy Porter  ------------- Systems Engineering --------
:Dell Computer Corp.   ------ jerry@terminus.us.dell.com ----
:---  70 4F BD AE 6D E9 D2 66  48 18 8B E7 64 7F 59 8F ---
:Support your Second Amendment rights to encryption technology.
:

I am working on this very thing. We will be using LPC encoding for
compression, IDEA for encryption, and DH key exchange for key handling.
We plan to use something better than DH ASAP (something less vulnerable
to man in the middle attacks). We plan to use 14.4kbps transmission
speed.

Lance